• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.7
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• pp.2872-2877
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• 2012

This paper discusses the development of the wearable personal cooling system for reducing thermal stress in hot environment. The personal cooling system is operated with the compact refrigeration system by compressing refrigerant. The compact refrigeration system is applied with the miniaturization and weight reduction for portable and wearable cooling system. The body heat is reduced by heat conduction with evaporator in direct cooling type. The cooling capacity of the wearable personal cooling system is approximately 100W and, the system could maintain the inside temperature of approximately 12-$13^{\circ}C$ lower than the ambient temperature. The weight of the wearable cooling system is about 3kg including vest, case, battery and all parts.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.122-126
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• 2006

Two types of pressurization system and low weight feeding piping system are developed. With sub-system tests, ullage pressure control performance was verified for 1 step and 2 step pressurization system and the feeding performance of feeding piping system was also verified. The weight of the feeding piping system is low enough for the application of launch vehicle. In addition, LOX conditioning system is developed for avoiding geysering and LOX temperature rise. Integrated performance was verified through integrated on-board feeding system performance tests.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.11
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• pp.7377-7384
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• 2015

Agricultural tractors must have a function of ROPS to protect drivers under roll-over accident. In this study, finite element analyses and an optimal design were performed to reduce the cost and the production period of the cabin frame of a tractor to pass the ROPS strength test. To confirm the pass of ROPS strength test of an initial design model, the results of deformation and principal strain from the analyses were evaluated. To reduce the weight of the cabin frame, design of experiment of Taguchi was implemented, and an optimal design was obtained. The weight of the optimal design model was reduced by 7% comparing with the initial design model.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.4
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• pp.326-333
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• 2011

This paper studies battery charging methods using existing motor inductance and 3-phase inverters without an additional charger to charge the battery of Plug-in Hybrid Electric Vehicles (PHEVs). As inverter switch control and motor coil used as the energy storage device for boosting make the system the boost converter, the additional charger is eliminated and volume, weight, and cost for the charger are reduced. Various charging methods according to topologies of the system and configurations of the controller are analyzed and verified by PSIM simulation.

• Journal of Korean Society of societal Security
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• v.3 no.2
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• pp.33-39
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• 2010

This study is to reduce the rate of drowning accident by using of buoyancy bag. People are exposed to the high risk of drowning accident when they have water leisure activities due to the lack of safety mind-set and shortage of safety products. In case of drowning accident, the rescue action is normally depending on the other people's assistance. Therefore, rescue activities which relyn the people doesn't improve the ratio of survival in the drowning accidents. The submarine specialists should use the buoyancy products to rescue the people in the drowning accident. The citizen can carry portable buoyancy product in the automobile as well as by hands anywhere and anytime. It will be effective rescue tool to save his/her life in the emergency. In addition, it will contribute to rescue other's life because it can be used immediately. There are 3 positive characteristics on the buoyancy bag. First, it is convenience. Documents and other stuffs can be kept in the bag. Second is safety. The material of buoyancy is placed in the inner of the bag. It is possible to float the person whose weight is 90 kg. Lastly, it is durability. It can be used long-term because the outer of the bag is made of anti-water material and anti-water zipper. As a result of performance analysis, it is evident that the buoyancy bag can be used to rescue the people in the drowning accident as a indirect rescue tool compared with the current other rescue products. It is recommended that the design of outer box and performance of buoyancy are required to be improved in order to contribute more to rescue people in the accident.

• Journal of the Korean Chemical Society
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• v.66 no.3
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• pp.202-208
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• 2022

In this study, we tried to obtain the optimal conditions to reduce odors generated from pig wastewater using magnesia (MgO) through in-situ test after producing a reactor for removing odors. For this purpose, the filling amount of magnesia, the injection amount of pig wastewater, the aeration method, the aeration amount and the aeration time were considered. The field experiment was conducted at Cheongwoon Livestock Farm, which has a pig wastewater reservoir. As the amount of magnesia added to the weight of wastewater (500 kg) increases, the amount of ammonia (NH₃) and hydrogen sulfide (H₂S) generated tended to gradually decrease. As a result of the test, ammonia and hydrogen sulfide in the pig wastewater decreased up to 65% and 77%, respectively, for 2 days aeration after 0.8% of magnesia was added to the reaction tank. The initial pH of the pig wastewater in the reactor was 8.2, and the pH was found to be 9.2 when magnesia was added up to 0.8%. In the light of this trend, it can be known that magnesia gradually increases the pH in the pig wastewater and makes it weakly alkaline. As the pH increases, part of the ammonia gas present in the pig wastewater vaporizes into the air and the remaining part is removed by precipitation after chemical bonding with dissolved magnesium ions and phosphate ions. In order to remove the odor of pig wastewater and turn it into compost, most of the existing livestock farms go through a six-month aeration process using microorganisms. In contrast, the current study proved the effect of removing odors from pig wastewater within 2 days through chemical reactions that do not affect microbial activity.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.121-121
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• 2009

자동차는 코너 주행 시 In-corner와 Out-corner 의 바퀴 궤적이 달라지므로, 특별한 장치가 없이 좌우 구동 측의 바퀴가 같은 속도로 회전을 하게 되면 정상적인 주행이 불가능하다. 따라서 정상적인 코너 주행이 가능 하려면, 코너 안쪽 바퀴보다 바깥쪽 바퀴가 더 빨리 회전해야 하며 이러한 회전 차를 보상받지 못할 경우 바깥쪽 바퀴가 끌리는 현상이 발생하는데 이를 방지하기 위해 디퍼렌셜 기어가 필요하다. 현재 디퍼렌셜 기어는 디퍼렌셜 케이스와 링기어를 볼트로 체결하는 조립 공법을 통해 생산되고 있다. 하지만 볼트 체결 공법은 조립을 위한 볼트와 볼트 체결을 위한 플랜지와 볼팅을 위한 홀을 가공하는 공정이 필요하기 때문에 재료비 절감 및 생산 효율 향상에 매우 불리하고 볼트체결을 위한 부분 때문에 불필요한 무게가 증가하게 된다. 따라서 본 연구에서는 이러한 기계적 체결 방식을 레이저 용접 방식으로 대체하여 재료비를 절감하고 무게 저감을 통해 주행성능을 향상시키고자 하였다. 링기어의 소재는 침탄처리강(SCM420H)이며 디퍼렌셜 케이스의 소재는 주철(GCD500)을 사용하고 있다. 주철은 용접시 용접부와 열영향부에서 마르텐사이트 조직과 레데브라이트, 시멘타이트 조직이 생성되며 고탄소 모재의 탄소 확산으로 인한 부분 혼합영역에서 탄소 합금이 생성되어 균열이 발생하는 등 용접성이 매우 좋지 않은 것으로 알려져 있다. 이러한 주철의 난용접성을 해결하는 방법으로는 고탄소 모재 용접시 발생하는 탄소의 확산을 억제하거나 예열이나 후열 처리를 통한 냉각 속도의 제어하는 방법과 오스테나이트 안정화 원소를 첨가한 필러와이어를 사용하여 용접시 마르텐사이트와 시멘타이트의 성장을 방해하는 방법 등이 이용되고 있다. 본 연구에서는 예열처리나 후열처리를 통한 주철의 용접법은 대량 생산을 통한 원가절감을 노리는 자동차 업계의 특성에 비추어 볼 때 비용이나 프로세스 구성 면에서 적용하는 것이 어려울 것이라 판단하여 Ni-base filler metal을 통한 주철의 용접법을 선택하였고 그 결과 실차에 적용하기 위한 비틀림 강성 테스트나 내구 테스트는 통과하였으나 NVH 테스트 결과 볼팅 체결 방식에 비하여 소음이 커지는 문제가 발생하고 링기어의 HAZ부가 고경화 되는 문제가 발생하였다. 때문에 용입깊이를 초기 시제품인 5mm에서 4mm로 변경시켜 입열량 감소 및 용접변형을 줄여 소음 문제를 해결하고자 하였으며 링기어의 침탄층을 1mm 절삭하여 링기어 HAZ부의 고경화 문제를 해결하고자 하였다. 이러한 용접 구조 변경이 용접변형 및 강성과 피로에 미치는 영향력을 알아보고자 용접 및 열처리 상용 소프트웨어인 SYSWELD, 구조해석 상용소프트웨어인 NX_NASTRAN, 피로 해석 상용 소프트웨어인 FEMFAT을 이용하여 시뮬레이션 하였고 실제 구조 변경한 용접 시제품과 비교, 분석하였다.

• Korean Journal of Food Science and Technology
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• v.37 no.5
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• pp.736-740
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• 2005

As an alternative of yeast, various concentrations to prepare hypo-allergenic bread (HAB). Addition of sodium bicarbonate increased $CO_2$ emission, but at higher than 2.0% caused bitter taste compared to other mixtures. Addition of sucrose significantly increased $CO_2$ emission. HABs 7 ($NaHCO_3$ 2.0g+sucrose 0.63 g) and 8 ($NaHCO_3$ 2.0g+sucrose 1.0g) showed higher grain and color scores. HAB 5 ($NaHCO_3$ 1.5g+sucrose 1.0g) and 6 ($NaHCO_3$ 1.5g+sucrose 2.0g) gave higher aroma and taste scores. HAB 5 showed significantly higher overall acceptability (p<0.05) score than others, whereas HABs 7 and 8, regardless of high external sensory qualities, showed lower overall acceptabilities than HAB 5 due to bitter taste. Prototypical HAB was obtained using wheat flour (100g) and water (62mL) incubated at $37^{\circ}C$ for 4 hr for treatment of b.p pretense (100mg) before adding sodium bicarbonate (1.5%), sucrose (1.0%), NaCl (1.0%), and citric acid (1.0%).

• Korean Journal of Organic Agriculture
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• v.10 no.2
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• pp.95-109
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• 2002

This study focussed to find out the agronomic effect of high quality compost mixed with brown seaweed and to determine the optimum mixing rate of seaweed to compost for environmentally benign organic farming. The experiment was conducted in lysimeters at Experimental Farm of Dankook University with Chinese Cabbage(Bulam #1), and the crop growth such length and width of leaf, biomass of Chinese Cabbage were checked, the content of chlorophyll, sugar, vitamin C, nitrate in outer leaf and idler leaf was determined. It was observed that nitrate content was dramatically decreased in the plot of mixture with seaweed, while biomass and content of Vitamin C were increased steeply in the plot of mixture with seaweed. The best result was gained the 0.25% mixture of brown seaweed with compost.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.2
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• pp.109-117
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• 2022

There has been an increasing number of studies on photovoltaic energy generation system in an offshore site with the largest energy generation efficiency, as increasing the researches and developments of renewable energies for use of offshore space and resources to replace existing fossil fuels and resolve environmental challenges. For installation and operation of floating photovoltaic systems in an offshore site with harsher environmental conditions, a stiffness of structural members comprising the total system must be reinforced to inland water spaces as dams, reservoirs etc., which have relatively weak condition. However, there are various limitations for the reinforcement of structural stiffness of the system, including producible size, total mass of the system, economic efficiency, etc. Thus, in this study, a floating breakwater is considered for reducing wave loads on the system and minimizing the reinforcement of the structural members. Wave reduction performances of floating breakwaters are evaluated, considering size and distance to the system. The wave loads on the system are evaluated using the higher-order boundary element method (HOBEM), considering the multi-body effect of buoys. Stresses on structural members are assessed by coupled analyses using the finite element method (FEM), considering the wave loads and hydrodynamic characteristics. As the maximum stresses on each of the cases are reviewed and compared, the effect of floating breakwater for floating photovoltaic system is checked, and it is confirmed that the size of breakwater has a significant effect on structural responses of the system.