• KIEAE Journal
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• v.13 no.6
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• pp.105-111
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• 2013

This study aims to suggest the PV lightshelf and to evaluate the power performance of the photovoltaic systems easily mounted on the windows. For the study, the suggested systems consist of two parts as fixed and movable PV modules. Also, tempered glass and polycarbonate are used on the surface protection materials for solar cells of PV lightshelf. By using polycarbonate, the weight of PV lightshelf is lighter about 20%. The field tests are performed for five days by using real size models. The voltage, current and electric powers are measured as basic performances of PV lightshelf. Also, the irradiation, brightness and module surface temperature are measured as outside conditions. As results, the power performance of tempered glass PV lightshelf shows about 11(%) higher thant that of polycarbonate PV lightshelf. And the power performance shows about 5(%) higher in a horizontal system. This results could be used to develop the effective PV lightshelf in next study.

• Aerospace Industry
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• v.83
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• pp.24-33
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• 2004

1903년 미국 노스캐롤라이나의 모래언덕에서 시작된 인류 최초의 동력비행이 성공한 지 100년이 지난 지금, 항공산업은 비약적인 발전을 이룩하였다. 1,2차 대전을 거치는 동안 항공산업은 양적으로나 질적으로 많은 성장을 이루었다. 이렇듯 항공산업은 군사적 이용이 산업을 발전시켜 왔다고 해도 과언이 아닐 정도로 군사적 목적의 이용이 중요한 몫을 차지하고 있다. (중략)

• Bulletin of the Korea Photovoltaic Society
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• v.8 no.1
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• pp.9-19
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• 2022

전 세계적으로 탄소중립에 대한 중요도가 증가하면서 국내에서도 이를 위한 그린뉴딜 정책이 발표되었다. 태양전지는 탄소중립 실현을 위한 중요한 신재생에너지 중의 하나이며, 최근에는 실외 거치형 발전 시스템을 넘어 건축 창호 및 외벽, 자동차 선루프, IoT 센서 구동용 전원 등 다양한 분야에서 제품들과의 융합화를 위한 소재/시스템 기술이 개발되고 있다. 본 원고에서는 유기태양전지를 활용한 Product integrated 태양전지 소재 및 응용 기술에 대해서 살펴보고자 한다. 특히, 실내 조명을 이용한 유기태양전지 기술에 대해 자세히 논의하고자 한다.

• Journal of Ocean Engineering and Technology
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• v.29 no.2
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• pp.120-127
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• 2015

When a deep-seabed lifting pump is kept this device has bending and deformation in the axis due to its long length(8m). These influences can be caused a breakdown. Therefore, a mounting must be developed to keep the lifting pump safe. This paper discusses the hydraulic cylinder design of the lifting pump and structural safety estimation of the mounting using SBD(simulation-based design). The multi-body dynamic simulation method is used, which has been used in the automotive, structural, ship building, and robotics industries. In this study, the position and diameter of the hydraulic cylinder were determined based on the results of the strokes and buckling loads for the design positions of the hydraulic cylinder. A structural dynamic model of the mounting system was constructed using the determined design values, and the structural safety was evaluated using this dynamic model. According to these results, this system has a sufficient safety factor to manufacture.

• Korean Journal of Plant Resources
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• v.20 no.4
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• pp.336-341
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• 2007

This study was carried out to investigate geographic variation in needle characteristics of Pinus densiflora, one of the most economically important tree species in Korea. Needles were collected from 35 natural populations and their morphological and anatomical characteristics were studied. ANOVA showed statistically significant differences among populations as well as among individuals within populations in needle length, needle width, number of stomata row, density of stomata in $0.25mm^{2}$, number of serrations in 0.5mm, and number of resin ducts. In all these traits, variance components among individuals within populations were larger than those among populations. The density of stomata in $0.25mm^{2}$ increased as the latitudes and elevations of the populations increased, while the number of serrations in 0.5mm decreased as the decrease of latitudes and elevations. The number of resin ducts was higher in inland populations than in coastal populations. The resin duct index appeared to be higher in western populations than in eastern populations. Cluster analysis based on morphological characteristics divided populations into three groups. The third group was composed of populations selected from the Taebaek mountains. The number of serrations in 0.5mm of this group was lower than that of other two groups, while the density of stomata in $0.25mm^{2}$ was higher.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.640-647
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• 2018

Many harbor structures have been constructed, and some structures are now under construction in Korea, which is a peninsular state and a logistics hub in Northeast Asia. Expansions and extensions of existing harbors are also being planned to meet increasing natural disaster threats. Wave-dissipation concrete blocks are recycled or discarded based on the personal experience of engineers only, and there are no safety checks or criteria. To check the safety of used blocks, material evaluations were done by visual inspection of blocks on the ground and under water and from 20 non-destructive measurements of the rebound hardness test and 3 concrete core samples. Wave-dissipation blocks are sometimes fully or partially damaged in the process of transferring and mounting them or during construction. Therefore, a safety check is essential for recycling blocks with an evaluation of materials while considering the construction phases. To do this, a block was modeled with a 3D finite element method using ADINA, and impact analyses were done according to the transfer, mounting, and construction phases. From the results of the impact analyses and material evaluation, the safety checks and reasonable evaluation of used blocks were examined, and detailed construction methods are proposed. The methods are expected to maximize the reuse of used wave-dissipation blocks from an economical point of view.

• Journal of the Korean Geosynthetics Society
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• v.10 no.2
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• pp.13-19
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• 2011

Precast culvert system is generally constructed with a series of process such as excavation, ground mitigation, placement of culverts, anti-leakage packing between adjacent culverts, post-tensioning for PS strands and backfilling. In this process inappropriate ground mitigation often causes differential settlement and, correspondingly, makes water-leakage to be occurred between adjacent boxes. This study was performed to understand the behavioral characteristics of recently proposed precast foundation plate to support precast culvert system through on-site pilot construction. The gap between two adjacent culverts, increment of earth pressure at the bottom of culvert, vertical settlement of top of the culverts were monitored using various sensors. The monitoring results showed that the proposed foundation plate provides better culvert system in the points of less gap development, earth pressure and settlement at the adjacent of two culverts.

• Korean Journal of Plant Taxonomy
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• v.46 no.4
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• pp.413-419
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• 2016

Two unrecorded naturalized species, Stachys agraria Schltdl. & Cham. and Dracocephalum moldavica L (Lamiaceae), are newly reported in Korea. Stachys agraria and D. moldavica were found at Seogwipo-si on Jeju-do and at ChunChen-si in Gangwondo in Korea, respectively. Stachys agraria is distinguished from other related Korean taxa by corolla of 2.4-5.2 mm long with six to twelve flowers in the node. Its local name is "Ae-gi-seok-jam-pul" based on shorter than longer corollar. Dracocephalum moldavica was distinguishable from other Dracocephalum in Korea by the following combination of characters, oblong to ovate-triangular ($1.7-2.4cm{\times}0.8-1.2cm$) leaves and rough crenate at the margin. This taxon is referred to as 'Hyang-yong-meo-ri' in Korean based on its fragrance. We provide a description, illustrations, photographs, and a key of related taxa in Korea.

• Journal of The Korean Society of Grassland and Forage Science
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• v.29 no.1
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• pp.51-62
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• 2009

This study was carried out development a new composting system to lower copper and zinc concentration in plg sludge compost and conduct an inquiry into the possibility of crop cultivation. The concentrations of nitrogen, phosphorus and pH averaged 4.4%, 6.3% and 7.57, respectively, which were higher concentrations than in commercial organic fertilizers, and the concentrations of copper and zinc averaged 805 and 1,704 mg/kg, respectively, which were beyond the heavy metal concentration limit in byproduct compost. Hydrated citric acid I lowered the concentrations of copper and zinc by 58% and 97%, respectively and hydrated oxalic acid II lowered the concentrations of copper and zinc by 48% and 56%, respectively in pig sludge compost. Lower concentrations of copper and zinc in pig sludge resulted from the enhanced hydrated-citric acid concentration in organic acid solution mixed with distilled water. The concentrations of copper and zinc were 330, and 41 mg/kg in the pig sludge treated with 100% hydrated citric acid. Agitation composting system stabilized the compost earlier than the stationary composting system, in which the stabilization condition was confirmed by higher temperature by $4^{\circ}C$ at highest temperature and 7 days earlier cooling down after highest temperature. The levels of germination index (G.I) 80 were obtained 15 and 20 days after composting in agitation and stationary composting system, respectively. The concentrations of copper and zinc were 2.4 and 4.26 mg/kg respectively in soils amended with pig sludge compost after removing process of heavy metals by citric acid, but 8.0 and 22.37 mg/kg, respectively in soils amended with Pig Sludge. The concentrations of heavy metals was highest in com cultivated in soils amended with pig sludge. The copper and zinc concentrations In corn leaves were 75.2 and 50.56 mg/kg respectively, which were 4 and 2 fold higher than the com cultivated in soils amended with pig sludge compost after heavy metal removing process by hydrated citric acid.

• The Journal of Engineering Geology
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• v.24 no.1
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• pp.111-122
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• 2014

For accurate laboratory evaluations of soil deposits, it is essential that the samples are undisturbed. An artificial ground-freezing system is the one of the most effective methods for obtaining undisturbed samples from sand deposits. The objective of this study is to estimate the shear strengths and the characteristics of elastic waves of frozen-thawed and unfrozen specimens through the undrained triaxial compression test. For the experiments, Jumunjin standard sands are used to prepare frozen and unfrozen specimens with similar relative densities (60% and 80%). The water pluviation method is used to simulate the fully saturated condition under the groundwater table. When thawing the frozen specimens, the temperature is measured every minute. After the specimens are completely thawed, undrained triaxial compression tests are conducted using the same procedures as for the unfrozen specimens. During the triaxial tests (saturation, consolidation, and shear phase), compressional and shear waves are measured. The results show that the freeze-thaw process has minor effects on the peak deviatoric stress and shear strength values, and that the process does not affect the internal friction angle. The compressional wave velocity increases with increasing B-value to 1800 m/s in the saturation phase, but tends to remain constant in the process of consolidation and shearing. The shear wave velocity decreases with increasing B-value in the process of saturation, but changes velocity in accordance with the change in effective stress in the processes of consolidation and shearing. The compressional wave velocity has similar values regardless of the freeze-thaw process, but values of shear wave velocity are slighly lower in frozen-thawed specimens than in unfrozen specimens. This study is a preliminary experiment for estimating the shear strength and characteristics of elastic wave velocity in undisturbed frozen specimens that have been obtained using the artificial ground-freezing method.