Conventionally, metal materials are produced by subtractive manufacturing followed by melting. However, there has been an increasing interest in additive manufacturing, especially metal 3D printing technology, which is relatively inexpensive because of the absence of complicated processing steps. In this study, we focus on the effect of varying powder size on the synthesis quality, and suggest optimum process conditions for the preparation of AlCrFeNi high-entropy alloy powder. The SEM image of the as-fabricated specimens show countless, fine, as-synthesized powders. Furthermore, we have examined the phase and microstructure before and after 3D printing, and found that there are no noticeable changes in the phase or microstructure. However, it was determined that the larger the powder size, the better the Vickers hardness of the material. This study sheds light on the optimization of process conditions in the metal 3D printing field.

PURPOSES : In this study, the results of an intensive field survey of a composite pavement applied to an expressway in Korea are analyzed. The results are intended to be used as basic data for evaluating the composite pavement and for preparing quality control measures through a review and analysis of the change in the state of the tensile bonding strength of the composite pavement. METHODS : To evaluate, repeated field coring and indoor tensile bonding strength evaluations are conducted for five years, and the commonality evaluation of pavement using pavement condition investigation equipment is conducted annually. RESULTS : The results of this study show that the degree of reflective crack generation varies depending on the type of concrete pavement and type of asphalt mixture applied to the intermediate layer, and that the CRCP composite pavement exhibits better initial commonality than the JCP composite pavement. In addition, it is confirmed that the composite cross-section pavement section with MASTIC applied as an intermediate layer shows excellent adhesion performance between the lower concrete layers from the beginning of construction in all sections, as well as satisfied the quality control standards for good pavement and tensile adhesion even after approximately five years of public use. CONCLUSIONS : Based on a follow-up survey of the composite pavement testing sections, it is confirmed that the section constructed with the MASTIC intermediate layer and CRCP satisfies the quality control standards for good pavement conditions and tensile adhesion even after approximately five years of public use.

Strawberry is a stand-out cultivating fruit in Korea. The optimum production of strawberry is highly dependent on growing environment. Smart farm technology, and automatic monitoring and control system maintain a favorable environment for strawberry growth in greenhouses, as well as play an important role to improve production. Moreover, physiological parameters of strawberry plant and it is surrounding environment may allow to give an idea on production of strawberry. Therefore, this study intends to build a machine learning model to predict strawberry’s yield, cultivated in greenhouse. The environmental parameter like as temperature, humidity and CO2 and physiological parameters such as length of leaves, number of flowers and fruits and chlorophyll content of ‘Seolhyang’ (widely growing strawberry cultivar in Korea) were collected from three strawberry greenhouses located in Sacheon of Gyeongsangnam-do during the period of 2019-2020. A predictive model, Lasso regression was designed and validated through 5-fold cross-validation. The current study found that performance of the Lasso regression model is good to predict the number of flowers and fruits, when the MAPE value are 0.511 and 0.488, respectively during the model validation. Overall, the present study demonstrates that using AI based regression model may be convenient for farms and agricultural companies to predict yield of crops with fewer input attributes.

Compound K (20-O-β-(D-glucopyranosyl)-20(S)-protopanaxadiol)는 진세노사이드의 활 성성분이다. Compound K는 경구 투여 후 Rb1, Rb2 및 Rc가 사람의 장내 미생물의 β-glucosidase에 의 해 생물전환 과정을 거쳐 생성된다고 알려져 있다. 본 연구는 생물전환된 인삼농축액에서 얻은 compound K를 이용해 항염증 및 독성을 조사하였다. 세포독성평가 결과, compound K는 0.001∼1 μg/mL의 농도 범위에서 유의적인 세포독성은 나타나지 않았으며, LPS로 염증이 유발된 RAW 264.7 세포에서 TNF-α, MCP-1, IL-6 및 NO의 생성을 억제하는 것으로 확인되었다. 동일 농도범위에서 TNF-α 및 IFN-γ로 염증이 유발된 HaCaT 세포는 compound K의 처리로 인해 IL-8의 생성을 감소시키는 것으로 나타났지만, IL-6의 경우 일부 농도에서 생성을 감소시켰으나, 통계적인 유의성은 나타나지 않았다. Brine shrimp를 이 용한 치사율 검정법에서 compound K의 LC50는 0.37mg/mL로 다소의 독성을 함유하고 있는 것으로 나타 났으나 compound K가 35% 고함유된 생물전환물은 LC50가 0.87mg/mL로 나타나 상대적으로 낮은 독성 을 보였다. 따라서 이 생성물은 향후 여드름 완화용 화장품 개발에 사용할 수 있는 매우 우수한 기능성 소 재가 될 수 있을 것으로 기대된다.

The time series data of rotifer community focusing on the species number and total density were collected from 29 reservoirs located at Jeonnam Province from 2008 to 2016 quarterly. The reservoirs had similar weather condition during the study period, but their sizes and water qualities were different. To analyze the temporal dynamics of rotifer community, the medians, ranges, outliers and coefficient of variation (CV) value of rotifer species number and abundance were compared. For the temporal trend analysis, time series of each reservoir data were compared and clustered using the dynamic time warping function of the R package “dtwclust”. Small-sized reservoirs showed higher variability in rotifer abundance with more frequent outliers than large-sized reservoirs. On the other hand, apparent pattern was not observed for the rotifer species number. For the temporal pattern of rotifer density, COD, phytoplankton abundance fluctuation, and cladoceran abundance fluctuation have been suggested as potential factor affecting the rotifer abundance dynamics.

본고는 이동 동사 ‘来/去’의 문법화 양상과 이에 따른 상(相) 의미를 분석했다. ‘来/ 去’는 [VP+来/去]의 연동문을 기반으로 ‘이동’이라는 본 의미에서 방향성, 시간성, 결 과성, 상태 변화 등으로 의미 추상화가 진행되었고, 이에 따라 [완결], [계속]과 같은 상(相) 의미를 획득하였다. 또한, 명·청 시기까지 문장 끝에 위치하여 사건의 발생, 변화를 나타내는 “사태조사(事态助词)”로 사용되었는데, 이는 현대 중국어 문미 ‘了’ 와 유사한 성분으로 발화자의 관점에서 이미 발생한 사건을 관망하는 완료상의 속성 인 “현재 관련성”을 지니고 있다. 본고는 ‘来/去’가 지닌 사태조사로서의 의미 또한 본 의미 ‘이동’에서 시작된 문법화의 산물임을 확인할 수 있었다.

재해석 자료는 공간해상도가 저해상도이지만 풍력자원의 장기간 보정이나 수치기상예측 또는 전산유체역학과 연동하여 고 해상도로의 축소화에 활용될 수 있다. 본 연구에서는 재해석 자료의 전세계 풍속을 지형요소 등의 함수로 회귀 분석하였으며 향후 고 해상도 축소화에의 활용 가능성을 시험하였다. 다중선형회귀와 기계학습 모델로서 신경망, 랜덤 포레스트 모델을 적용하여 다양한 지 형형태별로 회귀 분석한 결과에 의하면 접합도(R2)가 각각 0.71, 0.95, 1.00으로 향상되었으며, 지형요소 중 위도, 셀 면적, 지형고도, 경 도, 지형 개방도 순으로 설명력이 높은 것으로 나타났다. 기본 신경망에 비해 수정 쌍둥이 신경망 모델은 불균질 데이터 대상 성능 개 선 효과가 있는 것으로 나타났다. 그럼에도 불구하고 본 연구에서 활용한 신경망 모델로는 데이터의 비선형성을 재현하는데 한계가 있 었으나 랜덤 포레스트 모델을 통해 이를 극복하였다.

본 연구는 여수 인근 13개 무인도 주변 해역의 굴 Crassostrea gigas (n=410, SH 43.3±11.4 mm) 에서 확인된 인터섹스 현상을 보고하고자 하였다. 전체 성비(암:수)는 1:1.1이었으나 채집 정점 별로 성비의 차이를 보였다. 가장도, 소경도, 중삼도에서는 암컷이 65% 이상의 높은 비율을 보 였으며, 송도, 초도, 부서도에서는 수컷이 65% 이상의 높은 비율을 나타냈다. 전체 intersexuality 는 약 12.8%로 암컷에서 약 34.7%, 수컷에서 약 64.3%로 수컷에서 높았다. Intersexuality는 가막만의 초도에서 약 43.8%로 가장 높았다. 조직학적으로 인터섹스는 intrafollicular type, interfollicular type, mixed type의 세 가지 형태로 나눌 수 있었다. 이들 세 가지 형태 가운데 intrafollicular type이 약 81.6%로 가장 우세하였다. 본 연구에서 보고된 굴의 인터섹스 원인에 관해서는 추후 세부적인 연구가 필요할 것으로 생각된다.

The traditional Korean heating system ondol, one of the most important characteristics of Korean architecture, still remains as hydronic floor heating. Various studies have been conducted on the modernization of ondol, but the process of introducing the hydronic floor heating has not been seriously studied so far. Therefore, this paper aims to demonstrate how the hydronic floor heating had been introduced to Korea, taking the 1950s and 1960s Haengchon, Jongam, and Mapo Apartments for example – these three are regarded as the first Korean apartment houses after the Korean War. While Western advanced construction technology was imported for these apartments, various methods of modernizing ondol were also considered. What was remarkable in these attempts is that hydronic floor heating first appeared in Mapo 1st Apartment in 1962, because this is the universal heating method in the present Korea. This fact signifies that the traditional principle of floor heating has been maintained, and it would also be meaningful in terms of architectural exchanges between East and West, if considered along with Wright’s application of the Korean heating principle to his houses since 1930s.

Gas springs applied to various industrial fields are generally composed of a cylinder, a piston rod, a cover, and a seal mount. Because of the thin wall of the cylinder, small gas springs are manufactured using a roller forming process that presses the cylinder wall into a groove of cover in the cylinder. In this study, finite element analysis and process design of roller forming are performed to systematically manufacture the small gas spring and develop a roller forming machine. In order to perform roller forming analysis, tensile tests of structural steel pipe are performed and mechanical properties are analyzed. Roller forming process parameters such as radius and depth of roller grooves are derived using the incompressible condition of plastic deformation theory and the results of finite element roller forming analysis. Using the derived roller shape, a roller forming machine is developed and prototypes of the small gas spring are manufactured. Finally, the dimensional accuracy of the manufactured gas spring prototypes is analyzed through three-dimensional shape measurement.

In this study, we investigated the effects of adding oat and lactic acid bacteria on the quality and functionality of yogurt. Yogurt was fermented with various lactic acid bacteria,; Lactobacillus acidophilus (LA), Lactobacillus delbrueckii sub. bulgaricus (LB), and Streptococcus thermophilussei (ST) and quality properties, β-glucan content, antioxidant activity were estimated. The quality of control and oat added yogurt (OY) showed significant differences depending on the type of strain and combination. The addition of oats significantly accelerated the lactic acid bacteria production, decreased the pH, and increased the titratable acidity and count of the viable cells compared to the control. Acid production was highest in ST, with the complex strains containing ST and LALBST showing high quality characteristics. The viscosity of oat yogurt was higher than that of the control group, and LALBST was also significantly higher than that of the control group. The β-glucan content of OY was 0.14-0.2%, and the organic acid content and antioxidant activity were also significantly increased by the addition of oats. As a result, it is thought that the addition of oats and a combination of lactic acid bacteria can be used for improving the quality and functionality of yogurt.

In this study, the antioxidant activity of methanol extracts of wheat sprouts grown in wild fields and cultivated fields and harvested at various times were analyzed to compare the quality characteristics of the wheat sprouts as a function of their cultivation and harvest time, as well as for the development of functional materials. The total polyphenolic and flavonoid content, as well as antioxidant activity of the wheat extracts, were subsequently analyzed. The ABTS radical scavenging activity of the wheat extract increased from 16.97 mg TEAC/g sample on cultivation day three in cultivated field wheat sprouts to 25.99 mg TEAC/g sample after seven days of wild field cultivation. The total polyphenol content increased from 17.08 mg GA eq/100 g in cultivated field wheat sprouts grown for three days to 28.70 mg GA eq/100 g after seven days of wild field cultivation. In addition, the flavonoid content increased from 7.02 mg catechin eq/100 g (7 days) to 8.47 mg/g after 12 days of wild field cultivation. Notably, the activity subsequently decreased. These results suggest that the wheat sprouts with higher biological activity were those produced from the wild field after 20 days.

본 연구는 십자화과 채소인 갓(Brassica juncea) 추출물 을 이용하여 지표성분인 sinigrin의 함량을 분석하고, 내분비계 교란물질 환경호르몬인 비스페놀 A (BPA)로 분화를 유도한 3T3-L1 전구지방세포에서 갓 추출물과 sinigrin 처 리에 대한 지방세포 분화 및 활성산소종(ROS) 생성 억제, 지방 생성 전사인자(PPARγ, C/EBPα, aP2)의 단백질 발현 감소 효능을 평가하였다. 연구 결과에 따르면 HPLC를 이용하여 측정한 갓 추출물 중 sinigrin의 함량은 21.27±0.2 mg/g 인 것으로 나타났다. BPA로 유도된 3T3-L1 전구지방세포에 서 XTT assay 결과 sinigrin 180 μM 및 갓 추출물 300 μg/ mL 농도에서 세포 독성을 보이지 않았으며, 지방세포 분화과정 중 세포 내 지방 축적량과 ROS 생성량을 비교하였을 때 갓과 sinigrin을 처리한 지방세포의 경우 지방축 적량 및 ROS 생성량 모두 유의적으로 감소시키는 것으로 나타났다. 또한, 갓 추출물 및 sinigrin을 처리하였을 때 지 방세포 분화를 조절하는 전사인자 PPARγ, C/EBPα 및 aP2 의 발현이 억제됨을 확인하였다. 이 결과를 통해 갓은 환 경호르몬 비스페놀 A로 유도된 지방세포 내 지방 축적 억제와 더불어 ROS 저감에 효과적으로 작용함을 확인하였다. 향후 sinigrin을 함유한 갓은 BPA로 인한 지질 대사 장애를 예방하는 천연물 유래 기능성 식품 소재로 활용할 가능성이 높은 것으로 기대되며, 추가로 임상 연구 및 작용기전 입증을 위한 in vivo 모델에서의 후속 연구가 진 행되어야 할 것으로 사료된다.

이 총설에서는 해양 연체동물 내 독소 분석을 하는 연구자들의 이해를 돕기 위하여, 국내에서 생산되거나 유통 되는 수산물 중 해양 생물독소에 오염될 수 있는 이매패류와 복족류 종들의 공식 명칭과 생태학적 특성을 소개하 였다. 또한 대표적인 생물군의 해부도를 통한 각 기관들의 위치와 공식적인 명칭을 알리고자 하였다. 향후 해양 생물독소 분석 관련 식품공전, 학술논문 및 보고서에 실험생물의 정확한 종명과 분석 기관의 명칭에 대한 통일 및 규격화가 필요하다.

이 논문의 목적은 2020년 11월에 타결된 역내포괄적경제동반자협정 (RCEP)에 한국, 중국, 일본이 참여한 각각의 요인들과 인도가 가입하지 않은 요인들을 구체적으로 분석하여 국제레짐이론의 시각에서 설명하는 것이다. 첫째, 한국이 가입한 주요 요인은 신자유주의 이론의 설명대로 교역의 확대를 통한 경제적 이득을 예상했기 때문이다. 또한 신현실주의 이론에서 예상하듯이 아세안과의 포괄적 협력을 강화하여 역내에서 한국의 상대적 지위와 영향력을 높이려는 의도에서 비롯되었다. 둘째, 중국이 RCEP에 가입한 주요 요인도 경제적 이득인데 이는 신자유주의 이론의 설명과 부합된다. 또한 신현실주의 이론에서 예상하듯이 중국은 역내에서 주도적으로 다자적 통상협력의 틀을 구축함으로써 기존의 지위와 영향력을 증대하려는 것이다. 셋째, 일본도 신자유주의 이론이 예상하듯이 주로 경제적 이득을 고려하여 RCEP에 가입하였다. 또한 RCEP을 통해 수준 높은 다자적 자유무역 질서를 확립하는데 리더십을 발휘하기 위함이다. 이러한 요인은 신현실주의 이론으로 설명된다. 반면에 인도가 RCEP에 가입하지 않은 주요인은 중국에 대한 상대적인 경제적 손실이 예상되어 자국의 상대적 지위와 영향력이 저하될 것을 우려하였기 때문인데 이러한 요인은 신현실주의 이론에 의해서 적절히 설명된다.

본 연구는 플라스틱 재료를 사용한 유공관 암거의 품질성능시험을 통해 간척지 농지 범용화에 적용가능 여부를 판단하였다. 직경 30mm, 50mm, 55mm의 폴리에틸렌 재질의 유공관을 사용하였으며, 품질성능평가 항목은 밀도시험, 인장강도시험, 충격강도시험, 투수시험을 실시하였다. 밀도시험결과는 모든 시험편에서 유공관 품질기준인 밀도 0.94g/㎤이상의 결과를 보였으며, 인장강도 시험은 직경 30mm와 직경 55mm는 24.5MPa이상으로 품질기준을 만족하지만, 직경 50mm 유공관에서 24.4MPa로 품질기준인 24.5MPa에 미흡하므로 보강이 필요한 것으로 나타났다. 충격강도시험은 모든 시험편에서 파괴도 5미만으로 품질기준을 만족하는 결과를 보였으며, 내면에도 이상이 없는 것으로 분석되었다. 투수시험 결과는 모든 시험편에서 품질기준인 0.1㎝/sec 이하를 만족하는 결과를 보였다. 본 연구에 적용한 주름유공관은 간척지 범용농지 에 지하배수암거로 사용이 가능한 것으로 평가되었다. 하지만 제품의 공장생산 시 품질관리가 미흡할 소지가 있으므로 현장반입 전 사전품질 관리가 필요하다고 판단된다.

A mid-story isolation system was proposed for seismic response reduction of high-rise buildings and presented good control performance. Control performance of a mid-story isolation system was enhanced by introducing semi-active control devices into isolation systems. Seismic response reduction capacity of a semi-active mid-story isolation system mainly depends on effect of control algorithm. AI(Artificial Intelligence)-based control algorithm was developed for control of a semi-active mid-story isolation system in this study. For this research, an practical structure of Shiodome Sumitomo building in Japan which has a mid-story isolation system was used as an example structure. An MR (magnetorheological) damper was used to make a semi-active mid-story isolation system in example model. In numerical simulation, seismic response prediction model was generated by one of supervised learning model, i.e. an RNN (Recurrent Neural Network). Deep Q-network (DQN) out of reinforcement learning algorithms was employed to develop control algorithm The numerical simulation results presented that the DQN algorithm can effectively control a semi-active mid-story isolation system resulting in successful reduction of seismic responses.

In this paper, a twisted shape structure with an elevation form favorable to the resistance of vibration caused by wind loads is selected from among the forms of high-rise buildings. The analytical model is a square, triangular, and hexagonal plane with a plane rotation angle of one degree from 0 to 3 degrees per each story. As a result of the analysis, as the twist angle increased, story drift ratio is increased. Responses with different eccentricity rates were shown by analytical models. Therefore planar shapes designed symmetrically to the horizontal axis of X and Y are considered advantageous for eccentricity and torsion deformation. In the case of the bending moment of the column, the response was amplified in the column supporting the base floor, the roof floor, the floor in which the cross-section of the vertical member changes, and the floor having the same number of nodes as the base floor. Finally, the axial force response of the column is determined to be absolutely affected by the gravity load compared to the lateral load.

As the size of market for electric vehicles and energy storage systems grows, the demand for lithium-ion batteries (LIBs) is increasing. Currently, commercial LIBs are fabricated with liquid electrolytes, which have some safety issues such as low chemical stability, which can cause ignition of fire. As a substitute for liquid electrolytes, solid electrolytes are now being extensively studied. However, solid electrolytes have disadvantages of low ionic conductivity and high resistance at interface between electrode and electrolyte. In this study, Li7La3Zr2O12 (LLZO), one of the best ion conducting materials among oxide based solid electrolytes, is fabricated through RF-sputtering and various electrochemical properties are analyzed. Moreover, the electrochemical properties of LLZO are found to significantly improve with co-sputtered Li2O. An all-solid thin film battery is fabricated by introducing a thin film solid electrolyte and an Li4Ti5O12 (LTO) cathode; resulting electrochemical properties are also analyzed. The LLZO/Li2O (60W) sample shows a very good performance in ionic conductivity of 7.3  108 S/cm, with improvement in c-rate and stable cycle performance.

The purpose of this study was to investigate the improvement effect of biomarkers through the supply of natural diet in the juvenile hybrid abalone (Haliotis discus discus♀*H. madaka♂). For the study, the shell length of about 17 mm and the total weight of 0.83 g were used. The feeding conditions were set as the natural diet group (dried laver) and the formulated diet group, and the experiment duration was 16 weeks. The survival rate was about 14% higher in the natural diet group than the formulated diet group, and growth was also faster in the natural diet group. Shell malformation rate was lower in the natural diet group (7.5%) than the formulated diet group (21.5%). In the biochemical composition, except for carbohydrates, both experimental groups showed similar values. The degeneration of epithelial cells in the hepatopancreatic tubule was lower in the natural diet group than the formulated diet group, and the activity of basophilic cell was higher in the natural diet group. These results indicate that it is worth considering the supply of natural diet for the breeding of juvenile hybrid abalone and the improvement of the quality of the formulated diet (H. discus discus♀*H. madaka♂).