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        검색결과 290

        1.
        2024.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this paper, the goal is to produce a target wheel that integrates the plate and CPS wheel among the components of the drive plate mounted on an automobile engine. We attempted to develop a manufacturing process technology for incremental forming of a target wheel with the desired thickness by rotating a disk-shaped thin plate material and deforming the plate using a forming device and tools. Incremental forming system was set up by establishing a forming process and designing and manufacturing the device and parts required for processing. It consists of a total of 4 stages of molding process, and the optimal roll design that can properly collect materials to prevent cracks or reverse steps at each stage is primarily important. After manufacturing the prototype, a material test was performed to confirm whether the mechanical properties of the deformed part were sufficient to make gear teeth.
        4,000원
        2.
        2024.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Recently, domestic fishing production of Japanese horse mackerel has been continuously decreasing. To achieve sustainable fishing of this species, it is essential to acquire its target strength (TS) for accurate biomass estimation and to study its ecological characteristics. To date, there has been no TS research using a broadband echosounder targeting Japanese horse mackerel. In this study, for the first time, we synchronized an underwater camera with a broadband frequency (nominal center frequency of 200 kHz, range: 160-260 kHz) to measure the TS according to the body size (16.8-35.5 cm) and swimming angle of the species. The relationship between Japanese horse mackerel length and body weight showed a general tendency for body weight to increase as length increased. The pattern of the frequency spectra (average values) by body length exhibited a similar trend regardless of body length, with no significant fluctuations in frequency observed. The lowest TS value was observed at 243 kHz while the highest TS values were recorded at 180 and 257.5 kHz. The frequency spectra for the swimming angles appeared to be flat at angles of –5, 0, 30, 60, 75, and 80° while detecting more general trends of frequency spectra for swimming angle proved challenging. The results of this study can serve as fundamental data for Japanese horse mackerel biomass estimation and ecological research.
        4,000원
        5.
        2024.04 구독 인증기관·개인회원 무료
        The baculovirus expression system (BES) utilize the p10 or polyhedrin promoter, a very late promoter that exhibits strong transcriptional activity primarily at the end of viral infection, to produce useful recombinant proteins. The burst sequence of the very late promoter is essential for strong transcription, and VLF-1 is a transcription factor that binds specifically to the burst sequence, and it has been reported that it can regulate the amount and timing of expression of protein by the very late promoter. Recently, a VLF-1 constitutively expressing cell line was constructed to increase the production of the target protein, but the effect was minimal. In this study, to find the optimal VLF-1 expression conditions to increase target protein production efficiency, we controlled the expression of VLF-1 through various promoters and evaluated the target protein expression efficiency by the p10 promoter accordingly.
        6.
        2024.04 구독 인증기관·개인회원 무료
        전 세계적으로 RNA 간섭(RNA interference, RNAi)을 활용한 해충방제제 연구가 활발히 진행되고 있다. 대표적 으로 Monsanto의 서부 옥수수 뿌리벌레(Diabrotica virgifera virgifera) 특이적 방제용 dsRNA (DvSNF7)를 발현하 는 옥수수 종자가 상용화 되었고, 2016년 이 종자가 국내 사료 및 식품용으로 수입이 승인 되었다. 본 연구는 국내 에 서식하는 좁은가슴잎벌레(Phaedon brassicae)를 Non-target 곤충으로 사용하여, 옥수수 종자에 사용된 DvSNF7 dsRNA의 잠재적 위해성을 평가했다. P. brassicae의 SNF7 유전자와 DvSNF7 dsRNA 간 Sequence유사성 을 확인했다. 다음으로 P. brassicae가 DvSNF7 dsRNA를 섭식할 수 있는 환경을 조성하여, 치사 효과 실험과 Sequence특이적인 Knockdown효과를 확인하였다. 그 결과, DvSNF7 dsRNA는 P. brassicae생존에 영향을 미치지 않았으며, P. brassicae의 SNF7유전자를 Knockdown시키지 않음을 확인했다. 이번 연구를 통해 D. virgifera virgifera와 같은 과인 P. brassicae 는 SNF7유전자 간 Sequence유사성이 있지만, Sequence특이성이 부족하여 생존과 유전자 발현에 영향을 주지 않음으로써 위해성이 낮음을 확인했다.
        8.
        2024.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 논문은 주로 현장조사와 문서수집을 통해 중국 윈난다이징포자치주 루이리시 더훙 다이족 전통마 을의 현황과 현대 사회발전이 덕홍 다이족 전통마을에 미치는 영향을 조사하였다. 먼저 더훙지역의 지 형, 기후 등 자연배경과 사회구조, 문화적, 역사적 배경을 통해 덕홍 다이족 마을의 입지선정에 대한 역 사적 이유를 확인하였다. 그 중 문헌조사를 통해 더훙시 다이족의 16개 무형문화재 보호마을 중 가장 잘 보존된 곳이 한사마을임을 확인하였고 다이족 전통마을 경관연구의 대상지로 선정하였다. 본 논문 에서는 한사마을을 공간구성과 경관요소로 나누어 조사 및 분석한 결과는 다음과 같다. 한사마을은 자 연공간, 농업공간, 생활공간, 도로공간, 공공활동공간으로 나누어져 있으며, 마을 외곽 경계부는 대나무숲으로 둘러싸여 독립적인 형태를 띤다. 내부 공간구성은 채두(寨頭), 채심(寨心), 채미(寨尾)의 세 결절점을 중심으로 형성되며, 이러한 구심점을 통해 전체 마을 공간의 조직과 원시종교, 상좌부 불교가 어우러져 내향성을 더욱 확고히 하는 형태를 보인다. 한사마을의 경관요소는 건축, 식재, 시설물로 구 분한 결과는 다음과 같다. 첫째, 건축경관 측면에서는 한사마을의 독특한 종교와 기후, 한족 문화의 영 향을 받은 독특한 빌라식(别墅式), 건란식(乾欄式) 건축양식을 확인했다. 둘째, 한사마을 현장조사를 통해 불교의 영향과 자급자족하는 등 상징성 및 실용성을 강조하는 식재경관의 특징을 발견하였다. 시 설물은 대불교의 도덕이론에 기초를 두고 있으며, 시설의 스타일과 기능도 이에 영향을 받은 것으로 분석되었다. 이상의 조사와 연구를 통해 한사마을의 공간 배치는 민족의 역사와 종교로부터 배태(胚 胎)된 결과라는 결론을 도출하였으며, 종교적 신념과 공동체적 정신이 마을 전체를 지배하고 행태를 통제하는 경관을 보임을 확인하여 마을의 특수성과 보전 가치를 입증하였다.
        4,500원
        9.
        2024.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, a core-shell powder and sintered specimens using a mechanically alloyed (MAed) Ti-Mo powder fabricated through high-energy ball-milling are prepared. Analysis of sintering, microstructure, and mechanical properties confirms the applicability of the powder as a sputtering target material. To optimize the MAed Ti-Mo powder milling process, phase and elemental analyses of the powders are performed according to milling time. The results reveal that 20 h of milling time is the most suitable for the manufacturing process. Subsequently, the MAed Ti-Mo powder and MoO3 powder are milled using a 3-D mixer and heat-treated for hydrogen reduction to manufacture the core-shell powder. The reduced core-shell powder is transformed to sintered specimens through molding and sintering at 1300 and 1400oC. The sintering properties are analyzed through X-ray diffraction and scanning electron microscopy for phase and porosity analyses. Moreover, the microstructure of the powder is investigated through optical microscopy and electron probe microstructure analysis. The Ti-Mo core-shell sintered specimen is found to possess high density, uniform microstructure, and excellent hardness properties. These results indicate that the Ti-Mo core-shell sintered specimen has excellent sintering properties and is suitable as a sputtering target material.
        4,000원
        10.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Effects-Based Operations (EBO) refers to a process for achieving strategic goals by focusing on effects rather than attrition-based destruction. For a successful implementation of EBO, identifying key nodes in an adversary network is crucial in the process of EBO. In this study, we suggest a network-based approach that combines network centrality and optimization to select the most influential nodes. First, we analyze the adversary’s network structure to identify the node influence using degree and betweenness centrality. Degree centrality refers to the extent of direct links of a node to other nodes, and betweenness centrality refers to the extent to which a node lies between the paths connecting other nodes of a network together. Based on the centrality results, we then suggest an optimization model in which we minimize the sum of the main effects of the adversary by identifying the most influential nodes under the dynamic nature of the adversary network structure. Our results show that key node identification based on our optimization model outperforms simple centrality-based node identification in terms of decreasing the entire network value. We expect that these results can provide insight not only to military field for selecting key targets, but also to other multidisciplinary areas in identifying key nodes when they are interacting to each other in a network.
        4,000원
        11.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        As an advanced study on the method of calculating the target revenue water ratio of local waterworks through the leakage component analysis method proposed by Kim et al. (2022), this study developed a model to calculate the achievable revenue water ratio within the specified project cost, the required project cost to achieve the specified target revenue water ratio, and the economically appropriate target revenue water ratio level by considering the leakage reduction cost and leakage reduction benefit for each revenue water ratio improvement strategy, and conducted an applicability evaluation of the developed model using actual field data. The procedure for calculating the target revenue water ratio of local waterworks considering economics proposed in this study consists of three stages: physical data linkage model construction, leakage component analysis, and economic analysis, and the applicability was evaluated for Zone H with branch type and the Zone M network type. As a result of the application, it was calculated that approximately 32.5 billion won would be required to achieve the target revenue water ratio of 70% in the Zone H, and approximately KRW 10.5 billion would be required to achieve the target revenue water ratio of 75% in the Zone M. If the business scale of Zones H and M was corrected to 10,000 ㎥/day of water usage, the required project cost for a 1% improvement in the revenue water ratio of Zone H was calculated to be 0.7642 billion won and 0.4715 billion won for Zone M.
        4,600원
        13.
        2023.11 구독 인증기관·개인회원 무료
        The cyclotron is an apparatus used for the production of radioactive isotopes through nuclear reactions, resulting in the inevitable emission of neutrons. Consequently, surrounding components become activated. The purpose of this study was to investigate the radiological characteristics of Havar foil, a periodic replacement part of the Targetry system. In this study, radioactivity and radiation dose were calculated based on the time of Havar foil replacement and equipment dismantling. The time to dismantle the equipment was set at one year after the equipment was shut down, based on the recently used 1g of Havar foil. All simulations were performed using the FLUKA program. First, in the simulation results, 11 elements (Re, W, Tc, Nb, Cu, Ni, Co, Fe, Mn, Cr, V) were converted into 36 radioisotopes by activation based on the replacement period. Based on radioactivity levels, major isotopes included 52Mn (77.63%), 56Co (13.36%), 96Tc (2.4%), and 95Tc (1.80%). Based on radiation dose rates, 52Mn (82.66%) and 56Co (13.45%) exhibited the highest levels. Furthermore, the dose rates at distances of 10 cm, 50 cm, and 100 cm were found to be 1.36E+1 mSv/hr, 2.24E+00 mSv/hr, and 8.80E-01 mSv/hr, respectively. Second, as of the time the equipment was dismantled, 20 radioactive isotopes of 10 elements, excluding short-lived nuclides, were generated. In terms of radioactivity, 56Co (45.83%), 55Fe (19.73%), 57Co (14.48%), and 54Mn (13.50%) were prominent. Regarding radiation dose rates, 56Co (92%) and 54Mn (7.32%) exhibited higher levels. Dose rates at distances of 10 cm, 50 cm, and 100 cm were calculated at 5.31E-01 mSv/hr, 8.80E-02 mSv/hr, and 3.47 E-02 mSv/hr, respectively. Third, according to the radioactive waste classification standards in the replacement and decommissioning stages, Havar foil was predicted to be low-level radioactive waste in terms of radioactivity. In addition, it was derived that a cooling period of approximately 12 years is necessary to satisfy the allowable dose for clearance level waste. In conclusion, Havar foil, which is periodically generated as radioactive waste, can cause radiation exposure to replacement workers. Therefore, special and careful management is required for the Havar foil of the cyclotron.
        14.
        2023.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        식물구계학적 특정종은 식물상 정보를 이용한 지역환경을 평가하는 주요 수단이며, 종의 선정과 평가는 식물구계 정보에 의거해서 이루어진다. 본 연구는 이러한 식물구계에 대해 학술적 진의를 규명하고자 하였다. 식물구계 관련 핵심문헌 7편을 검토하였으며, 식물구계 적용 근거를 비교 검증하였다. 1919년의 Nakai 울릉도 식물상 조사보고서는 식물구계에 관련한 일반적인 지리구분(지방)을 처음으로 기재했다. Oh는 1977년에 한국의 유관속식물에 대한 식물지리구계도를 처음으로 제시하였 다. 1978년에는 Lee & Yim이 중부와 남부를 가르는 구계도를 제시했고, 그 밖에 많은 연구자들에 의해 식물구계 경계는 조정되고 개정되었다. 마침내 2018년에는 Lee & Yim (1978)에서 변형된 식물구계학적 특정종의 식물구계도가 채택되었다. 그런데 이러한 식물구계들은 연구자 간에 차이가 있었고, 구계 지표 식물의 불일치성도 확인되었다. 그럼에도 그런 상이성에 대한 근거는 찾을 수 없었다. 결론적으로 도식화된 모든 식물구계도는 선험적으로 그은 임의 선에 의존하고 있었다. 본 연구는 식물구계학적 특정종이 환경영향평가 및 국가 식물상 평가를 위한 과학적 수단으로서 그 실효성과 실체성을 확보하기 위해 다음의 두 가지 생태학적 전략을 제안했다 : 종분포 고유성(nativeness) 정보를 바탕으로 하는 식물상 및 식물구계의 성취와 서식처 기반(habitat-based) 식물상 장기모니터링 시스템의 구축.
        4,000원
        15.
        2023.10 구독 인증기관·개인회원 무료
        해충에 이용되는 화학적 기피제는 생태계를 파괴할 수 있으며 내성을 가진 생물체로의 진화를 촉진한다. 같은 종의 생물끼리의 의사소통 수단인 페로몬을 이용하면 다른 종에게 영향을 미치지 않으면서 특정 곤충에 특이적 으로 작용하는 방충제를 제작할 수 있을 것이라 생각된다. 본 연구는 초파리(Drosophila)의 페로몬 2종류를 추출 하여 초파리의 기피도 및 유인도와 번식률을 확인하고자 한다. ℃, 광주기 12h/12h의 동일한 조건에서 사육하 며 10마리당 헥세인 10를 사용하여 암컷의 표피에서 CHC 페로몬과 수컷의 페로몬샘에서 cVA 페로몬을 추출 한다. 연령, 성별, 교배 여부에 따라 관찰통에 각각의 페로몬을 처리하여 지정구간에 분포하는 초파리의 수를 계수하여 기피도 및 유인도를 확인한다. 관병에 암수 1쌍을 투입하고 하루에 1번 선정한 페로몬을 투여하며 산란 수을 측정한다. 이 연구를 통해 CHC가 수컷 초파리에 대한 기피 효과가 있음을 확인하였으며 추출되는 수컷의 연령이 높을수록 cVA에 의한 번식률 감소가 크게 나타났다. 본 연구를 통해 페로몬을 통한 초파리의 방제 가능성 을 확인하였으므로 다른 곤충의 방제에도 적용할 수 있을 거라 기대한다. 페로몬은 생물 농축과 같은 환경적 영향이 없으며 소량으로 유의미한 결과를 도출했다는 점에서 의의가 있으며 상용화를 통해 해충에 의해 피해를 해결할 수 있을 것이라 기대한다.
        17.
        2023.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This paper studied the problem of determining the optimal inventory level to meet the customer service target level in a situation where the customer demand for each branch of a nationwide retailer is uncertain. To this end, ISR (In-Stock Ratio) was defined as a key management indicator (KPI) that can be used from the perspective of a nationwide retailer such as Samsung, LG, or Apple that sells goods at branches nationwide. An optimization model was established to allow the retailer to minimize the total amount of inventory held at each branch while meeting the customer service target level defined as the average ISR. This paper proves that there is always an optimal solution in the model and expresses the optimal solution in a generalized form using the Karush-Kuhn-Tucker condition regardless of the shape of the probability distribution of customer demand. In addition, this paper studied the case where customer demand follows a specific probability distribution such as a normal distribution, and an expression representing the optimal inventory level for this case was derived.
        4,000원
        18.
        2023.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was conducted to select target fish species as baseline research for accumulation analysis of major hazardous chemicals entering the aquatic ecosystem in Korea and to analyze the impact on fish community. The test bed was selected from a sewage treatment plant, which could directly confirm the impact of the inflow of harmful chemicals, and the Geum River estuary where harmful chemicals introduced into the water system were concentrated. A multivariable metric model was developed to select target candidate fish species for hazardous chemical analysis. Details consisted of seven metrics: (1) commercially useful metric, (2) top-carnivorous species metric, (3) pollution fish indicator metric, (4) tolerance fish metric, (5) common abundant metric, (6) sampling availability (collectability) metric, and (7) widely distributed fish metric. Based on seven metric models for candidate fish species, eight species were selected as target candidates. The co-occurring dominant fish with target candidates was tolerant (50%), indicating that the highest abundance of tolerant species could be used as a water pollution indicator. A multi-metric fish-based model analysis for aquatic ecosystem health evaluation showed that the ecosystem health was diagnosed as “bad conditions”. Physicochemical water quality variables also influenced fish feeding and tolerance guild in the testbed. Eight water quality parameters appeared high at the T1 site, indicating a large impact of discharging water from the sewage treatment plant. T2 site showed massive algal bloom, with chlorophyll concentration about 15 times higher compared to the reference site.
        5,100원
        19.
        2023.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 360도 파노라마 동영상을 활용하여 해상풍력 경관의 유형을 분류하고 유형별 경관 선호 매 트릭스 요소에 따른 경관 선호도를 분석하고자 한다. 이를 위해 첫째, 연구대상지로 제주 탐라해상풍력 단지로 선정하였으며, 연구대상지를 조망할 수 있는 지점들을 추출하고 방문하여 360도 파노라마 동영 상을 촬영하였다. 둘째, 구축된 360도 파노라마 동영상 자료를 바탕으로 경관의 미학적 특성을 분석하 고 해상풍력 경관의 유형을 분류했다. 셋째, 해상풍력 경관의 유형별로 경관 선호 매트릭스 요소와 경관 선호도를 설문조사했다. 넷째, 수집된 데이터를 활용하여 해상풍력 경관 유형별 선호 매트릭스 요소에 따른 경관 선호도 관계를 분석했다. 분석 결과 해상풍력 경관 유형이 High Continuity(HCN), High Color (HCL), Low Visual Impact(LVI), High Visibility(HVI)로 분류되었다. 또한, HCN경관 선호도에 영향을 주 는 요소로는 응집성이, HCL경관 선호도에 영향을 주는 요소로는 응집성과 신비성이, LVI경관 선호도 에 영향을 주는 요소로는 응집성과 복잡성이, HVI 경관 선호도에 영향을 주는 요소로는 응집성과 가독 성이 도출되었다. 본 연구 결과를 바탕으로 해상풍력 경관 선호도 향상을 위한 전략으로 (1)시각적 영향 을 줄일 수 있는 식재계획 및 동선설계, (2)해상풍력 터빈의 생상 대비 극대화, (3)해상풍력 터빈 설치전 경관 시뮬레이션을 제안하였다.
        4,000원
        20.
        2023.05 구독 인증기관·개인회원 무료
        Metakaolin-based geopolymers have shown promise as suitable candidates for 14C immobilization and final disposal. It has been shown that the physicochemical properties of metakaolin wasteforms meet, and often far exceeding, the strict compression strength and leaching acceptance criteria of the South Korea radioactive waste disposal site. However, it is not possible to analyze and characterize the internal structure of the geopolymer wasteform by conventional characterization techniques such as microscopy without destruction of the wasteform; an impractical solution for inspecting wasteforms destined for final disposal. Internal inspection is important for ensuring wastes are homogenously mixed throughout the wasteform and that the wasteform itself does not pose any significant defects that may have formed either during formulation and curing or as a result of testing prior to final disposal. X-ray Computed Tomography (XCT) enables Non-Destructive Evaluation (NDE) of objects, such as final wasteforms, allowing for both their internal and external, characterization without destruction. However, for accurate quantification of an objects dimensions the spatial resolution (length and volume measures) must be know to a high degree of precision and accuracy. This often requires extensive knowledge of the equipment being used, its precise set-up, maintenance and calibration, as well as expert operation to yield the best results. A spatial resolution target consists of manufactured defects of uniformed dimensions and geometries which can be measured to a high degree of accuracy. Implementing the use of a spatial resolution target, the dimensions of which are known and certified independently, would allow for rapid dimensional calibration of XCT systems for the purpose of object metrology. However, for a spatial resolution target to be practical it should be made of the same material as the intended specimen, or at least exhibit comparable X-ray attenuation. In this study, attempts have been made to manufacture spatial resolution targets using geopolymer, silica glass, and alumina rods, as well as 3D printed materials with varying degrees of success. The metakaolin was activated by an alkaline activator KOH to from a geopolymer paste that was moulded into a cylinder (Diameter approx. 25 mm). The solidified geopolymer cylinder as well as both the silica glass rod and alumina rod (Diameter approx. 25 mm) we cut to approximately 4 mm ± 0.5 mm height with additional end caps cut measuring 17.5 mm ± 2.5 mm height. All parts were then polished to a high finish and visually inspected for their suitability as spatial resolution targets.
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