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        검색결과 9,736

        441.
        2024.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 민간시장의 절화 유통 현황을 조사하여 국내 절 화 시장 유통 및 판매의 기초 자료로 제공하고자 수행하였다. 조사 기간은 2022년 5월부터 10월까지이며, 민간시장 내 판 매 점포 수, 취급 품목, 수입국 및 품목 등을 비교 및 분석하 였다. 민간시장은 서울 서초구 반포동에 위치한 강남터미널 꽃시장을 대상으로 판매 품목 및 수입 국가 등을 조사하였고, 비교 대상인 공영시장의 경우 한국농수산식품유통공사 화훼 유통정보에서 제공되는 양재동 화훼공판장 거래 품목을 조사 하였다. 조사 결과, 민간시장의 월별 절화 판매 점포 수는 평 균 143개였다. 민간시장에서는 5월을 제외하고 장미 판매 매 장이 가장 많았다. 5월에는 카네이션 판매 매장이 가장 많았 으며 장미, 리시안셔스, 거베라가 그 뒤를 이었다. 민간시장 점포 내 수입 품목의 원산지는 호주, 중국, 콜롬비아, 이스라 엘, 이탈리아, 일본, 네덜란드, 페루, 남아프리카 공화국, 미 국, 베트남 등으로 조사되었다. 취급 품목은 민간시장이 69개 로 공영시장 18개에 비해 약 3.8배 많았으며, 이는 민간시장에서 수입 절화가 더 많이 유통되고 있음을 시사한다. 민간시 장은 공영시장과 달리 유통 정보를 알 수 있는 시스템이 없어 소비자들이 제품의 원산지, 품질, 가격 등을 파악하기 어렵다. 따라서, 민간시장의 절화 유통 정보를 소비자들에게 정확히 제공할 필요가 있으며, 이를 통한 투명한 거래 제공 및 소비자 의 신뢰도를 높이는 것이 중요하다.
        4,300원
        442.
        2024.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        가는잎향유[Elsholtzia angustifolia (Loes.) Kitag.]는 화형 이 아름답고, 정유 특유의 향기가 좋아서 분화용 및 지피용 관 상식물로 수요가 증가하고 있고, 전초에는 약효가 있다고 알 려져 있다. 본 연구는 가는잎향유의 육묘에 미치는 플러그 트 레이 셀 사이즈, 파종립수, 차광정도, 추비농도 등의 영향을 구명하기 위하여 수행되었다. 연구결과, 플러그 트레이 셀 사 이즈는 용량이 증가할수록 유묘의 초장, 엽수, 마디수, 근장, 지상부 생체중이 유의적으로 증가하였다. 파종 립수는 2립 파 종 시 가장 효율적이었고, 파종량이 증가할수록 생육이 감소 하였다. 차광정도가 높아질수록 초장은 증가하였고, 경직경, 엽수, 마디수는 55% 차광에서 가장 우수하였다. 추비 처리 시 공시비료 1000배 처리구에서 생육이 가장 양호하였다. 따라 서 가는잎향유의 육묘 시 162셀 트레이에 원예상토를 채운 다음 셀 당 2립 파종한 후 55% 차광막이 설치된 육묘상에서 공시비료 1000배로 엽면시비하는 것이 가장 효과적인 것으로 생각된다.
        4,000원
        443.
        2024.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Determining the number of operators who set up the machines in a human-machine system is crucial for maximizing the benefits of automated production machines. A man-machine chart is an effective tool for identifying bottlenecks, improving process efficiency, and determining the optimal number of machines per operator. However, traditional man-machine charts are lacking in accounting for idle times, such as interruptions caused by other material handling equipment. We present an adjusted man-machine chart that determines the number of machines per operator, incorporating idleness as a penalty term. The adjusted man-machine chart efficiently deploys and schedules operators for the hole machining process to enhance productivity, where operators have various idle times, such as break times and waiting times by forklifts or trailers. Further, we conduct a simulation validation of traditional and proposed charts under various operational environments of operators’ fixed and flexible break times. The simulation results indicate that the adjusted man-machine chart is better suited for real-world work environments and significantly improves productivity.
        4,000원
        444.
        2024.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Cerebrovascular disease (CVD) refers to a condition wherein the normal functioning of the brain is impaired, resulting in either temporary or permanent damage. The causes of CVD include both hemorrhagic and ischemic events. A cerebrovascular accident (CVA) refers to a condition that occurs acutely. A CVA typically involves a sudden blockage of blood supply to the brain or the rupture of blood vessels, causing damage to brain tissue. This results in impairment of crucial brain functions and can manifest in various neurological signs. This study investigated characteristics of the signalment, clinical symptoms, lesion locations, and prevalence of CVA diagnosed using a 3.0T MRI in dogs. The breeds included 5 Maltese and one each of Poodle, Pomeranian, Chihuahua, Shih-tzu, and Yorkshire terrier. There was one neutered male, five intact males, two spayed females, and two intact females. The median age and weight were 7.5 years and 3.39 kg, respectively. Clinical signs included gait abnormality in five dogs, and four dogs exhibited seizures. Additionally, there were cases of head tilt or turn (n=3) and nystagmus (n=1). The most frequently affected region was the cerebrum (n=7), followed by the cerebellum (n=3), brainstem (n=2), and thalamus (n=1). Three cases exhibited multiple lesions among these regions. In this study using a 3.0T MRI scanner, the prevalence rate was 4.39%, which was higher than that reported in previous studies.
        4,000원
        445.
        2024.03 KCI 등재후보 구독 인증기관 무료, 개인회원 유료
        Oral bacterial infections substantially affect the development of various periodontal diseases and oral cancers. However, the molecular mechanisms underlying the association between Fusobacterium nucleatum (F. nucleatum ), a major periodontitis (PT)-associated pathogen, and these diseases require extensive research. Previously, our RNAsequencing analysis identified a few hundred differentially expressed genes in patients with PT and peri-implantitis (PI) than in healthy controls. Thus, in the present study using oral squamous cell carcinoma (OSCC) cells, we aimed to evaluate the effect of F. nucleatum infection on genes that are differentially regulated in patients with PT and PI. Human oral squamous cell carcinoma cell lines OSC-2O, HSC-4, and HN22 were used. These cells were infected with F. nucleatum at a multiplicity of infection of 100 for 3 hours at 37℃ in 5% CO2. Gene expression was then measured using reverse-transcription polymerase chain reaction. Among 18 genes tested, the expression of CSF3, an inflammation-related cytokine, was increased by F. nucleatum infection. Additionally, F. nucleatum infection increased the phosphorylation of AKT, p38 MAPK, and JNK in OSC-20 cells. Treatment with p38 MAPK (SB202190) and JNK (SP600125) inhibitors reduced the enhanced CSF3 expression induced by F. nucleatum infection. Overall, this study demonstrated that F. nucleatum promotes CSF3 expression in OSCC cells through p38 MAPK and JNK signaling pathways, suggesting that p38 MAPK and JNK inhibitors may help treat F. nucleatum-related periodontal diseases by suppressing CSF3 expression.
        4,000원
        446.
        2024.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Ischemic stroke is caused by a blockage of the cerebral artery, which leads to a severe neurological disorder. Chlorogenic acid is a phenolic acid found mainly in plants such as coffee beans, eggplants, and carrots. It exerts a neuroprotective effect against cerebral ischemic damage. Bcl-2 family protein is a representative apoptosis regulatory protein. Bcl-2 and Bcl-xL act as apoptosis inhibitors, while Bax and Bad act as apoptosis inducers.The interaction of Bcl-2 family protein plays an important role in determining cell fate. The aim of this study was to investigate whether chlorogenic acid modulates the interaction of Bcl-2 family proteins during ischemic injury. Middle cerebral artery occlusion (MCAO) surgery was performed to induce cerebral ischemia. Chlorogenic acid (30 mg/kg) or phosphate buffered saline was intraperitoneally injected to adult male rats 2 h after MCAO surgery. Neurobehavioral tests were performed to confirm the neuroprotective effect of chlorogenic acid 24 h after MCAO injury, and immunoprecipitation analysis was performed to investigate the interaction of Bcl-2 family protein. MCAO damage showed signs of severe neurological disorders, while chlorogenic acid improved these disorders. Results of immunoprecipitation analysis were as follows. Interaction between Bax and Bcl-2 or Bcl-xL was decreased in MCAO injury, chlorogenic acid prevents these decreases. In contrast to Bax, Interaction between Bad and Bcl-2 or Bcl-xL was increased in MCAO injury, chlorogenic acid prevents these increases. Furthermore, chlorogenic acid attenuated MCAO-induced increase of capase-9. In conclusion, our findings demonstrate that chlorogenic acid exerts a neuroprotective effect against cerebral ischemic injury by modulating interaction of Bcl-2 family proteins.
        4,000원
        447.
        2024.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 논문에서는 빙하가 녹아 갈라져서 떠내려 온 새끼 펭귄이 다시 펭귄 무리로 되돌아가기 위 해서 길을 찾아 나서는 퍼즐 어드벤처 게임을 제안한다. 플레이어 40명의 로그 기록과 설문지 를 분석한 결과를 바탕으로 제안하는 게임의 특징을 살펴보고자 한다. 첫째, 제안하는 게임은 새끼 펭귄이 얼음 덩어리를 밀어서 길을 만들어 이동하는 직관적인 규칙을 제공한다. 로그 기 록에서 플레이 평균 시간은 19분이며, 이를 19개의 리스폰 지점으로 나누면, 구간별 플레이 평균시간은 1분이다. 설문에서 게임 목표 명확성은 4.45점, 게임 난이도는 4.16점을 받았다. 둘째, 제안하는 게임은 가마우지가 새끼 펭귄에게 도움말을 제시하는 등 유용한 정보를 친절 하게 제공한다. 전체 플레이 평균 시간은 baseline이 24분이고, kinder UI가 19분이다. kinder UI에서 새끼 펭귄이 얼음 덩어리를 덜 밀고, 게임 재시작을 덜 하고, 더 빨리 상호작 용하여, 문제를 빨리 해결한다. 설문에서 게임 스토리 이해는 4.15점, 유용한 정보는 4.45점을 받았다. 셋째, 제안하는 게임은 남극과 유사한 환경을 제공하여 몰입도를 상승시킨다. baseline에 비해서 kinder UI에서 다양한 게임 오브젝트와 더 적극적으로 상호작용을 시도하 고, 미션 완료 후 더 오랫동안 오로라를 지켜봤다. 설문에서 게임 캐릭터 선호도는 4.56점, 게 임 환경 만족도는 4.22점을 받았다.
        4,000원
        448.
        2024.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this investigation, we synthesized a novel quaternary nanocomposite, denoted as RGO-Ba(OH)2/CeO2/TiO2, through a straightforward and cost-effective solid-state synthesis approach. The as-prepared composites underwent a series of comprehensive characterizations, including XRD, FTIR, TGA-DTA, XPS, SEM, EDAX, and TEM analyses, affirming the successful synthesis of a quaternary nanocomposite with well-interconnected nanoparticles, nanorods, and sheet-like structures. Further, our electrochemical performance evaluations demonstrated that the electrochemical capacitance of the RGO-Ba(OH)2/CeO2/ TiO2 nanocomposite achieved an impressive value of 445 F g− 1 at a current density of 1.0 A g− 1, particularly when the mass ratio of CeO2 and TiO2 was maintained at 90:10. Furthermore, the specific capacitance retained a remarkable 65% even after 2000 cycles at a current density of 6 A g− 1 in a 3 mol KOH electrolyte. Comparatively, this outstanding electrochemical performance of the RGO-Ba(OH)2/CeO2/TiO2 (90:10) nanocomposite can be attributed to several factors. These include the favorable electrical conductivity and large specific surface area provided by graphene, TiO2, and Ba(OH)2, the enhanced energy density and extended cycle life resulting from the presence of CeO2, and the synergistic contributions among all four components. Therefore, the RGO-Ba(OH)2/CeO2/TiO2 nanocomposite emerges as a highly promising electrode material for supercapacitors.
        4,000원
        449.
        2024.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The untreated effluent dropping into the environment from various textile industries is a major issue. To solve this problem, development of an efficient catalyst for the degradation of macro dye molecules has attracted extensive attention. This work is mainly focused on the synthesis of nickel–manganese sulfide decorated with rGO nanocomposite (Ni–Mn-S/rGO) as an effective visible photocatalyst for degradation of textile toxic macro molecule dye. A simple hydrothermal method was used to synthesize Ni–Mn-S wrapped with rGO. The prepared composites were characterized using various techniques such as X-ray diffraction (XRD), high-resolution scanning electron microscopy (HR-SEM), high-resolution transmission electron microscopy (HR-TEM), Fourier transform infra-red spectrometer (FTIR), and ultra violet–visible (UV–Vis) spectroscopy. The photocatalytic performance of nickel sulfide (NiS), manganese sulfide (MnS), nickel–manganese sulfide (Ni–Mn-S), and Ni–Mn-S/rGO nanocomposite was assessed by analyzing the removal of acid yellow (AY) and rose bengal (RB) dyes under natural sun light. Among these, the Ni–Mn-S/rGO nanocomposite showed the high photocatalytic degradation efficiency of AY and RB dyes (20 ppm concentration) with efficiency at 96.1 and 93.2%, respectively, within 150-min natural sunlight irradiation. The stability of photocatalyst was confirmed by cycle test; it showed stable degradation efficiency even after five cycles. This work confirms that it is an efficient approach for the dye degradation of textile dyes using sulfide-based Ni–Mn-S/rGO nanocomposite.
        4,600원
        450.
        2024.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study aimed to identify and analyze the effects of both isothermal heat treatment temperature and residence time on the formation of mesophase in coal tar pitch, especially with respect to its microstructural and crystalline evolution. The formation and growth of mesophase resulted in a decrease in d002 and an increase in Lc, and the degree of such variation was larger when the isothermal heat treatment temperature was higher. In isothermally heat-treated pitch, two distinct domains were observed: less developed crystalline carbon (LDCC) and more developed crystalline carbon (MDCC). When pitch was isothermally heat-treated at 375 °C for 20 h, d002 was 4.015 Å in the LDCC and 3.515 Å in the MDCC. Higher isothermal heat-treatment temperatures accelerated the formation, growth, and coalescence of mesophase. Indeed, in the pitch specimen isothermally heat-treated at 425 °C for 20 h, d002 was 3.809 Å in the LDCC and 3.471 Å in the MDCC. The evolution of mesophase was characterized by pronounced inflection points in d002 curves. It was found that the emergence of these inflection points coincided with pronounced changes in the microstructure of mesophase. This finding confirmed the relationship between inflection points in d002 and the microstructure of mesophase.
        4,200원
        451.
        2024.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The challenge of incorporating photothermal conversion function into chitosan (CS) hybrid fibers lies in balancing functionality and mechanical properties. In this study, we successfully prepared a chitosan/graphene oxide/gelatin (CS/GA/GO) hybrid fiber using the wet spinning process, achieving improved mechanical properties and efficient photothermal conversion capabilities. When compared with pure CS fiber with a breaking strength of 1.07 cN/dtex, the breaking strength of the CS/ GA composite fiber increased by 46.73%, while the CS/GA/GO hybrid fiber showed an even greater increase of 85.98%. In addition, the introduction of gelatin (GA) led to secondary scattering of near-infrared light, enhancing the photothermal conversion efficiency. As a result, the CS/GA/GO hybrid fiber exhibited a faster temperature rise rate and higher maximum temperatures (94.3 °C, 103.0 °C, and 111.3 °C) as compared to the CS/GO hybrid fiber. The successful incorporation of GA not only improved the mechanical properties but also enhanced the photothermal performance of the hybrid fiber.
        4,200원
        452.
        2024.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study aimed to explore sustainable fashion design plans and directions by analyzing Marine Serre’s collection. Previous research was reviewed to derive classifications of the aesthetic characteristics of sustainable fashion design. This classification was then used to analyze the characteristics of the Marine Serre collection. Design analysis was conducted on Marine Serre’s 2018 FW to 2023 SS collections. Marine Serre’s sustainability characteristics are functionality, surprise, handicraft, and inclusion. The results are as follows. First, functionality is the highest among the four characteristics and includes the functionality of movement, the functionality of form, and futurism. This characteristic was observed in the use of all-in-one body suits, pockets, and workwear, showing the will and values of designers who value daily activity. Second, surprise includes the scarcity of materials and the unexpectedness of composition. The value of the clothing is enhanced by the use of scarce materials not typically used in clothing. In addition, Marine Serre is highly regarded for expanding clothing into life by incorporating material upcycling into the theme of the collection. Third, handcrafted features include exaggerated decorations, logo, retro designs, and natural properties, and intentional utilization is differentiated. Marine Serre’s signature pattern suggests a suitable expression for the fabric to use the crescent moon for the season. Fourth, the collection expresses themes of inclusivity and cultural diversity. The results indicate that Marine Serre wants to contribute to a better future characterized by global coexistence.
        4,900원
        453.
        2024.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Although interest in eco-friendly fashion products is increasing among scholars and industry leaders, the concept of eco-friendly products remains unclear, preventing consistent assessment of which fashion products are eco-friendly. This study conducted a content analysis of eco-friendly product information from 87 domestic and 102 foreign brands to reveal key standards for categorizing eco-friendly fashion products. Product characteristic information was coded according to the four material-based standards (i.e., organic material, regenerative material, alternative material, and sustainably produced/upcycled material). Consistency between coders was confirmed by Cohen’s kappa. In results, eco-friendly fashion products are categorized by four material-based standards and two certification standards (i.e., certified, not certified). Among the four material-based categories, the greatest number of domestic and foreign companies produced eco-friendly products that were classified as the regenerative material group. In addition, companies acquired eco-friendly certifications related to the use of organic, regenerative, and alternative materials. The greatest number of eco-friendly material brands used for eco-friendly fashion products belonged to the regenerative material group. Based on the study results, a typology of eco-friendly products was suggested. This typology can benefit practitioners and academics by highlighting a need for classification system for the eco-friendly fashion products, as well as by providing insight into the categorization of eco-friendly fashion products.
        5,800원
        454.
        2024.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The chemical composition of 86 species of native plants in Korea, including plants to be afforestation, was analyzed. The chemical composition of the species analyzed was different. The species with the highest extractable content was Viburnum dilatatum (3.91%), and the species with the lowest extractable content was Ligustrum lucidum (0.11%). The lignin content ranged from 12 to 39%, with an average of 25%. The species with the highest lignin content was Chaenomeles lagenaria (39.37%). Hemicellulose content ranged from 18 to 52%, with the highest species being Thuja occidentalis (51.22%) and Eucommia ulmoides (48.84%). Cellulose content ranged from 25 to 58%, and the species with the highest content were Prunus serrulata (57.67%), Diospyros kaki (57.14%), Aesculus turbinata (53.29%), Albizia julibrissin (53.02%), and Zelkova serrata (52.29%). The chemical composition was different for each use taxon of 86 plant species. The lignin content was the highest in the fruit group and the lowest in the group other than recommended species for afforestation. Cellulose content was highest in non-reforestation-recommended tree species and lowest in fruit trees. In classification according to tree height, lignin content was higher in shrubs than in tall trees, and cellulose content was highest in tall trees. Between deciduous and evergreen trees, the lignin content was high in deciduous trees (26.46%), and the cellulose content was also high in deciduous trees (44.01%). As a result of analyzing the correlation between each compound, there was a difference. There tended to be a positive correlation between extractives and lignin content. There was a negative correlation between extractives and holocellulose content, hemicellulose and cellulose. The higher extract content affected the cellulose content much more than hemicellulose. Also, the higher the lignin content, the lower the cellulose content. The species with low lignin content and high cellulose content were Diospyros kaki and Prunus serrulata var. spontanea. This result is expected to be primary data for bioenergy, pulp industry and bioindustry.
        4,200원
        455.
        2024.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In the summer of 2018, the Korea-Japan (KJ) region experienced an extremely severe and prolonged heatwave. This study examines the GloSea6 model's prediction performance for the 2018 KJ heatwave event and investigates how its prediction skill is related to large-scale circulation patterns identified by the k-means clustering method. Cluster 1 pattern is characterized by a KJ high-pressure anomaly, Cluster 2 pattern is distinguished by an Eastern European highpressure anomaly, and Cluster 3 pattern is associated with a Pacific-Japan pattern-like anomaly. By analyzing the spatial correlation coefficients between these three identified circulation patterns and GloSea6 predictions, we assessed the contribution of each circulation pattern to the heatwave lifecycle. Our results show that the Eastern European highpressure pattern, in particular, plays a significant role in predicting the evolution of the development and peak phases of the 2018 KJ heatwave approximately two weeks in advance. Furthermore, this study suggests that an accurate representation of large-scale atmospheric circulations in upstream regions is a key factor in seasonal forecast models for improving the predictability of extreme weather events, such as the 2018 KJ heatwave.
        4,200원
        456.
        2024.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study examines the rise of the Body Positive Movement on TikTok and its role as a form of online content activism influencing the fashion design and industry. Through a combination of literature review and case study methodology, the study explores the expression techniques and thematic types of Body Positive Movement on TikTok. Reviews of literature, previous studies, online articles, fashion journals, and relevant search terms on TikTok informed a definition of Body Positive Movement and an analysis of its formation and rise. The research findings confirm the impact TikTok content on Body Positive Movement has on the fashion industry in addressing external factors (i.e., ‘Appearance’, ‘Race’, ‘Aging’, ‘Physical Disability’) and intrinsic factors (i.e., ‘Acceptance of Diversity’, ‘Self-Esteem’, ‘Rejection of Stereotypes’, ‘Appropriate Representation’, ‘Information Provision’). The key external factor , ‘Appearance’, includes subcategories such as ‘Body Shape’, ‘Body Hair’, ‘Skin’, and ‘Facial Features’. TikTok content creators on fashion creatively combine music, emojis, and visual storytelling to exhibit positive self-perception concerning these factors. A significant finding of the study is that short clips predominantly manifesting external factors differentiate into informative or enlightening videos associated with intrinsic factors. The study underscores Body Positive Movement's important influence on the fashion industry from design to presentation.
        5,700원
        457.
        2024.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study explores the profound impact of varying oxygen content on microstructural and mechanical properties in specimens HO and LO. The higher oxygen concentration in specimen HO is found to significantly influence alpha lath sizes, resulting in a size of 0.5-1 μm, contrasting with the 1-1.5 μm size observed in specimen LO. Pore fraction, governed by oxygen concentration, is high in specimen HO, registering a value of 0.11%, whereas specimen LO exhibits a lower pore fraction (0.02%). Varied pore types in each specimen further underscore the role of oxygen concentration in shaping microstructural morphology. Despite these microstructural variations, the average hardness remains consistent at ~370 HV. This study emphasizes the pivotal role of oxygen content in influencing microstructural features, contributing to a comprehensive understanding of the intricate interplay between elemental composition and material properties.
        4,000원
        458.
        2024.01 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In the merger-driven galaxy evolution scenario, dust-obscured quasars are considered to be an intermediate population between merger-driven star-forming galaxies and unobscured quasars; however, this scenario is still controversial. To verify this, it is necessary to investigate whether dust-obscured quasars have higher Eddington ratio (λEdd) values than those of unobscured quasars, as expected in the merger-driven galaxy evolution scenario. In this study, we derive black hole (BH) masses of 10 dust-obscured quasars at z ∼ 2, during the peak period of star-formation and BH growth in the Universe, using a newly derived mid-infrared (MIR) continuum luminosity (LMIR)-based estimator that is highly resistant to dust extinction. Then, we compare the λEdd values of these dust-obscured quasars to those of unobscured type-1 quasars at similar redshifts. We find that the measured log (λEdd) values of the dust-obscured quasars, −0.06 ± 0.10, are significantly higher than those of the unobscured quasars, −0.86 ± 0.01. This result remains consistent across the redshift range from 1.5 to 2.5. Our results show that the dust-obscured quasars are at their maximal growth, consistent with the expectation from the merger-driven galaxy evolution scenario at the epoch quasar activities were most prominent in the cosmic history.
        4,000원
        459.
        2024.01 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer (SPHEREx) will provide all-sky spectral survey data covering optical to mid-infrared wavelengths with a spatial resolution of 6.′′2, which can be widely used to study galaxy formation and evolution. We investigate the galaxy-galaxy blending in SPHEREx datasets using the mock galaxy catalogs generated from cosmological simulations and observational data. Only ∼0.7% of the galaxies will be blended with other galaxies in all-sky survey data with a limiting magnitude of 19 AB mag. However, the fraction of blended galaxies dramatically increases to ∼7–9% in the deep survey area around the ecliptic poles, where the depth reaches ∼22 AB mag. We examine the impact of the blending in the number count and luminosity function analyses using the SPHEREx data. We find that the number count can be overestimated by up to 10–20% in the deep regions due to the flux boosting, suggesting that the impact of galaxy-galaxy blending on the number count is moderate. However, galaxy-galaxy blending can marginally change the luminosity function by up to 50% over a wide range of redshifts. As we only employ the magnitude limit at Ks-band for the source detection, the blending fractions determined in this study should be regarded as lower limits.
        4,000원
        460.
        2024.01 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In order to attract students to the radio universe, we have constructed a three-element radio interferometer in the National Youth Space Center, Goheung, Korea. It consists of three 1.8 m off-axis parabola antennas with driving systems, sideband separation receivers operating in 12 GHz, a narrow band digitizer, and correlation software. We have used as many commercial products as possible to reduce development costs. The maximum separation of 20 m gives an angular resolution of ∼4′, and the shortest baseline of 3.8 m prevents a serious missing flux. Fringes are detected for several radio sources, including the sun and Cas A. After a rough relative calibration, we have derived visibilities for the sun, whose amplitudes are decreasing for longer baselines. We have made a solar image using the visibility amplitudes and closure phases, referring to the 17 GHz image by Nobeyama Radioheliograph. Developing a flexible real-time correlator seems most crucial if this kind of the system is to be used for more rigorous scientific studies.
        4,000원