• Proceedings of the KIEE Conference
• /
• 2000.07d
• /
• pp.2336-2338
• /
• 2000

고효율, 무공해의 신발전 기술인 연료전지 발전은 발전 용량 및 스택구성에 따라 차이가 있으나 기본적으로 저전압, 대전류 특성과 부하에 따라 발전 전압이 크게 변동하는 특성을 갖는 직류전원으로써 이를 상용으로 이용하기 위해서는 연료전지 발전 전력을 안정된 전력으로 변환하여 주는 장치가 필요하며, 이러한 전력 변환장치가 연료전지 발전의 최종 출력 전원의 질을 결정한다. 연료전지 전력변환장치는 전압조절기능, 승압 기능을 가져야 하고, 연료전지 본체와 부하를 안정하게 운전하기 위해 전력변환장치 뿐만 아니라 부하와 연료전지 본체의 운전상태 감지 기능, 각종 장치의 보호와 제어기능을 가져야 한다. 본 논문의 목적은 자동차용 연료전지 출력 전력변환장치의 종합제어장치의 설계를 위해 연료전지 스택시뮬레이터를 개발하는 것이다. 연료전지 스택 시뮬레이터는 연료전지 발전 특성과 일치하는 전력을 출력해 주는 직류전원 공급장치로써 이를 이용하여 연료전지 출력 전력변환장치의 종합제어장치를 충분한 예비실험과 수정, 보완함으로써 연료전지용 전력변환 시스템의 성능개선, 안정성 향상 등을 가질 수 있다.

• Journal of Digital Convergence
• /
• v.14 no.7
• /
• pp.397-402
• /
• 2016

This study discusses on the city-culture contents convergence design strategy which can be linked to the identity of the city through applying the graffiti on old-town of Dongducheon. First, the background and cultural asset of Dongducheon were researched. Second, the places revealing the identities were investigated. Third, the interviews with the college students in the city were performed. As the result, we found that using graffiti gains positive reaction as the reinforcement factor for the city identification. The exotic image made up by US military presence is evaluated as an important factor for the city identification. The Rock Festival is a representative cultural event derived by the cultural influence from the US military and is one of the crucial elements for the city identification. In this study, graffiti was proposed as the visual expression which can be harmonized with this culture and be reinforced for the city identity. Results of the study concludes with the strategy for the application of graffiti with the expectation for the improvement of city image of Dongducheon through the change of identity, urban regeneration, and making of pollution-free culture.

• Korean Journal of Medicinal Crop Science
• /
• v.1 no.2
• /
• pp.158-161
• /
• 1993

This experiments were carried out determine planting date for highest Yields and select an covering material for enhancement of environments in Cassia tora L.The highest Yields by regressions estimate produced 352 kg/10a at May 18. of coure, it is possible to plant at June and early-July in spite of slight decreas of Yields, therefore Cassia tora L. is benefit to establish cropping system with barley, wheat or other crops. The covering materials for highest yielding was Black-white nonporous PE(low density) and it out yielded about 53% than conventional cultivations. Cassia tora L. is possible to produce Without agricultural medicines because of little occurence of decrease except occuring of Damping off(Rhizoctonia solanikuhn) at early planting.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.18 no.5
• /
• pp.171-182
• /
• 2019

Bicycles are a pollution-free means of transportation. In addition to leisure, the use of bicycles is increasing as alternative eco-friendly transportation. Accordingly, bicycle accidents are also increasing. The purpose of this study is to implement bicycle black box technology to identify situation when a bicycle accident occurs. Currently, bicycle black box products are mainly based on video cameras, and are commercially available by adding various functions mainly on high resolution cameras and are sold at high prices. If a bicycle accident occurs, quantitative data on the accident location at the time of the accident and the state of the bicycle at the time of the accident is required. In this study, IMU sensor used to obtain acceleration and slope, and time and coordinates are obtained. In addition, real-time acceleration and tilt data while is stored in memory card and by using Bluetooth transmit to the smart phone owned by the in real time to prevent accidents and to monitor status.

• Journal of the Korean Applied Science and Technology
• /
• v.40 no.1
• /
• pp.179-187
• /
• 2023

Nanogenerators containing biomaterials are eco-friendly electronic devices in terms of being a non-polluting energy source and biodegradable electronic waste. In particular, the amount of waste will be also reduced if the biomaterial can be extracted from biowaste. In this study, a triboelectric nanogenerator was fabricated using animal collagen present in the skin of a mammal and its characteristion was proformed. The electro-anodic layer of the triboelectric nanogenerator was constructed by forming a collagen film using the spin coating method, and it was confirmed that the film was porous from scanning electron microscopy. The fabricated triboelectric nanogenerator exhibited an open-circuit voltage from 7 V at 3 Hz to 15 V at 5 Hz due to periodic mechanical movement, and a short-circuit current of 3.8 uA at 5 Hz. In conclusion, collagen-containing triboelectric nanogenerators can be power source for low-power operating devices such as sensors and are also expected to be useful for reducing electronic waste.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.8 no.4
• /
• pp.269-273
• /
• 1996

A new type of perforated block is presented to be used in the construction of a step seawall. Two-dimensional hydraulic model test is performed to compare the overtopping rates between the traditional non-perforated step seawall and the perforated step seawall constructed with the new type of perforated blocks. The overtopping rate of the perforated step seawall is lower than that of the traditional non-perforated step seawall. The new type of perforated step seawall may be used as an alternative for water-amenity seawall in the future.

• Advances in pediatric surgery
• /
• v.15 no.2
• /
• pp.157-160
• /
• 2009

Although the incidence of esophageal atresia (EA) is higher in twins than in singletons by two to three times, EA usually affects only one member of twins. We report one pair of twins concordant for EA. A 31-year-old healthy woman bore monozygotic female twins at 36 weeks of gestation. They weighed 2,216 and 2,480 g, respectively. They had EA with distal tracheoesophageal fistula and underwent primary esophageal anastomosis on the birth day and the $2^{nd}$ day of life, respectively. Twin A also had suspicious antral obstruction and pyloroplasty was done simultaneously with esophageal repair. She needed antral web excision for continued gastric stasis one month after $1^{st}$ operation and three balloon dilatations of the esophagus. Twin B recovered uneventfully.

• 한국신재생에너지학회:학술대회논문집
• /
• 2005.11a
• /
• pp.60-75
• /
• 2005

천연가스차량이 배출하는 미연 탄화수소 중 약 80%이상이 메탄으로 구성 되어있다. 메탄은 그 자체로 유독성 물질은 아니지만 이산화탄소와 더불어 지구온난화를 유발하는 온실가스로 향후 강력한 규제가 예상되는 물질로 이를 저감하는 기술 개발이 이루어져야하나 연료 특성상 이를 줄이는데 어려움이 있다. 최근 연구에 의하면 천연가스엔진에 수소를 일정량(15%이상) 첨가할 경우 배출가스 및 성능 이 상당량 개선되는 결과를 보이고 있다. 이는 종래 천연가스 연소의 문제점인 지연된 화염 전파 속도를 수소 연료를 첨가함에 따라 화염 전파속도를 촉진시켜 적정한 연소를 야기 시켜 미연탄화수소 배출이 줄어들고 열효율도 향상되는 결과를 보이고 있다. 이와 같이 수소와 천연가스연료의 각각의 장점을 활용한 Hy-thane 엔진을 개발할 경우 무공해엔진에 근접한 초 저공해 동력장치 개발이 가능하며 이에 대한 상용화 측면에서 산업용 발전기, GEHP, 차량용 엔진 등 활용도가 크기 때문에 그 개발이 절실히 필요하다고 할 수 있다. 따라서 본 과제에서는 이중연료를 사용하는 수소-천연가스 기관을 개발하고 이를 효과적으로 제어할 수 있는 제어시스템을 개발하여, 기관효율 향상과 배기가스저감을 이루었다.

• Proceedings of the KSME Conference
• /
• 2007.05a
• /
• pp.1379-1382
• /
• 2007

In this paper, we present a simplified analytic approach for the prediction of roll force to be applicable to the grooveless rolling. The approach is based on the deformation shape deduced from physical considerations and employs the assumption that the deformation homogeneously occurs in three directions. Strain and strain rate are calculated by the geometric relationships between those components and the prescribed deformation functions. Then, stress components are obtained from the Levy-Mises' flow rule. By integrating the stress components along the rolling direction, roll force are finally obtained. The prediction accuracy of the proposed model is examined through comparison with results obtained from the finite element analysis.

• Proceedings of the Membrane Society of Korea Conference
• /
• 2002.05a
• /
• pp.35-41
• /
• 2002

Dense oxygen ionic conducting materials can be used for oxygen separation membranes at high temperatures. However, they show relatively low permeation flux because of their large resistances. To reduce resistances and improve the oxygen permeation flux, thin dense yttria-stabilized-zirconia (YSZ)/Pd composite dual-phase membranes were fabricated by a new approach that combines the reservoir method and chemical vapor deposition (CVD). A thin porous YSZ layer was coated on a porous alumina support by dip-coating the YSZ suspension. A continuous Pd phase was formed inside pores of the YSZ layer by the reservoir method. The residual pores of the YSZ/Pd layer were plugged with yttria/zirconia by CVD to ensure the gas tightness of the membranes. The oxygen permeation fluxes through these composite membrane were 2.0$\times$10$^{-8}$ mol/cm$^2$.s and 4.8$\times$10$^{-8}$ mol/cm$^2$.s at 105$0^{\circ}C$ when air and oxygen were used as the permeate gases, respectively. These oxygen permeation values are about 1 order of magnitude higher than those of pure YSZ membranes prepared under similar conditions.