• 전력전자학회논문지
• /
• 제21권5호
• /
• pp.396-403
• /
• 2016

Usually, large-sized buses and trucks have a very high load. In addition, frequent braking during downhill or long-distance driving, causes the conventional method using the brake friction to have a problem in safety because of brake fade and brake burst phenomenon. Auxiliary brakes dividing the braking load is essential. Hence, environment-friendly auxiliary brakes, such as contactless brake rather than the engine auxiliary brake system are needed. A study aimed at improving the energy efficiency by recharging electric energy with changing mechanical to electrical energy that occurs when braking is actively in progress. In this paper, the voltage control method is utilized to recover the electric energy generated in the electromagnetic retarder instead of the eddy current. To regenerate the braking energy into the electrical energy, the resonant L-C circuit is configured in the retarder. The voltage generated in the retarder is simply modeled as a transformer. However, retarder voltage control in this paper is simulated by modeling the induction generator because this induction generator modeling is more practical than transformer modeling. The changes in the voltage of the resonance circuit, which depends on the switch pulse duration of the control device, were analyzed. A PI controller algorithm to control this voltage is proposed. The feasibility of modeling retarder and voltage controller are shown by using MATLAB Simulink in this paper.

• 에너지공학
• /
• 제29권3호
• /
• pp.86-90
• /
• 2020

이 논문은 네트워크로 연계된 에너지 클라우드, 에너지 커뮤니티 그리고 스마트시티에 참여한 프로슈머 머신들 간의 전력 직거래에 있어 위치증명방식이 적용된 블록체인 네트워크 기반 거래 시스템에 대한 고찰이다. 이 시스템은 위치증명기반 블록체인 네트워크 기술을 활용하여 자율 이동 중 전력 구매에 의한 배터리 재충전으로 장거리 이동이 가능해 질 수 있는 물류 배송 드론, 전력 구매와 판매가 모두 가능한 자율주행 전기 자동차 그리고 고정형태로 전력생산 및 판매가 가능한 태양광 가로등 및 전기충전기들 간의 전력 거래 시 인간의 개입 없이 머신들 간 최적 전력거래 매칭 및 정산 신뢰성을 제공 할 수 있다. 또한 다수이면서 서로 다른 공간에 존재하기 때문에 발생되는 다양한 거래 가격, 정책 그리고 인센티브들이 산재할 것으로 예상되는 에너지 클라우드를 경유하는 자율 운행 머신들 간의 사물 간 전력 직거래 비즈니스 모델을 소개한다.

• Journal of Acupuncture Research
• /
• 제28권2호
• /
• pp.49-55
• /
• 2011

Objectives : This study was to develop programmable and rechargeable electronic moxibustion device as an interdisciplinary research focusing on traditional Korean medicine. Methods : This device deployed several advances on safety and conveniences with the advantage of programmable heat stimulation, heating material and recharging method. The gradient of heat stimulation was programmed with the reference of previous studies and own measurements. The heat curve reached its efficacious stimulus temperature after three minutes, and maintained until 13 minutes with $42^{\circ}C$. We also incorporated feedback from field hospital experiences with the help of hospital staffs. Results : This device can prevent damages from skin burn and fire accidents, and control the smoke, smell and residue of moxa itself. Conclusions : This study will contribute for the development and improvement of efficacious and safe treatment methods for the traditional Korean medicine.

• 한국산업정보학회논문지
• /
• 제16권1호
• /
• pp.31-36
• /
• 2011

유비쿼터스 네트워크와 더불어 무선 센서 네트워크는 다양한 분야에 응용되고 있다. 무선 센서 네트워크의 노드들은 목표 지역에 비치되어 동작하게 되는데 그 공급원으로 대부분 배터리를 사용하고 있다. 배터리는 센서 네트워크의 응용에 제한된 에너지를 가짐으로써 교체나 충전 등의 어려움을 가진다. 따라서 센서노드의 수명을 연장시키기 위해 주변 환경으로부터의 에너지 하베스팅 기술 등이 연구 개발되고 있다. 특히 태양에너지는 다른 환경 에너지에 비하여 방대하고 짧은 시간에 많은 에너지를 얻을 수 있어 최근 널리 연구되어지고 있다. 본 연구에서는 Solar Cell을 이용하여 배터리 충전 및 센서노드를 구동하는 실험을 하고, 수집된 데이터와 배터리의 전압에 대한 분석을 통하여 센서노드를 구동하기 위해 필요한 배터리 충전시간과 센서노드 농작 가능성에 대하여 확인하였다.

• 한국해양공학회지
• /
• 제21권3호
• /
• pp.33-39
• /
• 2007

The more deeply the researches make progress in ocean researches including the seabed resource investigation or the oceanic ecosystem investigation, the more important the role of UUV gets. In case of study on the deep sea, there are difficulties in telecommunications between AUV and ships, and in data communication and recharging. Therefore, docking is required. In AUV docking system, the AUV should identify the position of docking device and make contact with a certain point of docking device. MOERI (Maritime & Ocean Engineering Research Institute), KORDI has conducted the docking testing on AUV ISIMI in KORDI ocean engineering water tank. As AUV ISIMI approachs the docking device, there is some cases of showing an unstable attitude, because the lights which is on Image Frame are disappeared. So we propose the docking algorithm that is fixing the rudder and stem, if the lights on image frame are reaching the specific area in the Image Frame. Also we propose the new docking device, which has a variety of position and light number. In this paper, we intend to solve the some cases of showing an unstable attitude that were found in the testing, which, first, will be identified the validity via simulation.

• Journal of Ecology and Environment
• /
• 제33권1호
• /
• pp.47-57
• /
• 2010

To understand day-to-day fluctuations in soil moisture content in Seoul, I simulated daily soil moisture content from 1908 to 2009 using long-term climatic precipitation and temperature data collected at the Surface Synoptic Meteorological Station in Seoul for the last 98 years with a hydrological simulation model, BROOK. The output data set from the BROOK model allowed me to examine day-to-day fluctuations and the severity and duration of droughts in the Seoul area. Although the soil moisture content is highly dependent on the occurrence of precipitation, the pattern of changes in daily soil moisture content was clearly quite different from that of precipitation. Generally, there were several phases in the dynamics of daily soil moisture content. The period from mid-May to late June can be categorized as the initial period of decreasing soil moisture content. With the initiation of the monsoon season in late June, soil moisture content sharply increases until mid-July. From the termination of the rainy season in mid-July, daily soil moisture content decreases again. Highly stochastic events of typhoons from late June to October bring large amount of rain to the Korean peninsula, culminating in late August, and increase the soil moisture content again from late August to early September. From early September until early October, another sharp decrease in soil moisture content was observed. The period from early October to mid-May of the next year can be categorized as a recharging period when soil moisture content shows an increasing trend. It is interesting to note that no statistically significant increase in mean annual soil moisture content in Seoul, Korea was observed over the last 98 years. By simulating daily soil moisture content, I was also able to reconstruct drought phenomena to understand the severity and duration of droughts in Seoul area. During the period from 1908 to 2009, droughts in the years 1913, 1979, 1939, and 2006 were categorized as 'severe' and those in 1988 and 1982 were categorized as 'extreme'. This information provides ecologists with further potential to interpret natural phenomenon, including tree growth and the decline of tree species in Korea.

• 한국방재학회 논문집
• /
• 제4권4호
• /
• pp.27-34
• /
• 2004

본 연구에서는 인공함양법을 적용한 유역에서의 유출특성 변화를 알아보기 위하여 실험유역을 설정하고 각각의 유역에 대하여 실제강우 실험과 강우모의 실험을 실시를 통하여 유출-침투특성을 분석하였다. 실강 우시 유출-침투특성 분석을 위해 2004년 7월 11일${\sim}$7월 17일 사이에 내린 4개의 강우사상에 대하여 분석을 실시한 결과 인공함양유역에서 유출이 발생하는 경우의 유출율 평균은 약 10.61%, 침투율 평균은 89.39%로 파악되어 유출되는 유량의 대부분이 인공함양법 적용에 의해서 침투가 가능한 것으로 나타났으며, 강우모의 실험에서는 강우강도의 변화와 상관없이 1시간의 지속시간을 가지는 60mm/hr ${\sim}$ 100mm/hr 구간에서 유출되는 유량 없이 전량이 침투되는 것으로 나타났다. 그러나, 인공함양시설을 설치한 경우라도 장기간 강우 발생시 주위의 지하수 변화에 의해서 유출이 발생할 수 있으므로 주변의 지하수위에 대한 지속적인 관찰이 요망된다.

• 에너지공학
• /
• 제19권2호
• /
• pp.92-102
• /
• 2010

플러그인 하이브리드 전기자동차(Plug-in Hybrid Electric Vehicle, PHEV)는 하이브리드 전기자동차(Hybrid Electric Vehicle, HEV)의 일종으로, 배터리 용량을 HEV보다 더욱 증대시키고 배터리의 충전을 전력망으로부터 할 수 있도록 한 자동차이며, 순수 배터리 전기자동차(Plug-in Battery Electric Vehicle, PBEV)는 전력망으로부터 전기를 배터리에 충전하여 저장하고 배터리에 저장된 전기만을 이용하여 운전가능한 자동차이다. 최근에 PHEV와 PBEV에 대한 관심과 개발이 전세계적으로 급속하게 증가하고 있다. 그러므로 이들 전력망 충전식 전기자동차가 전력망의 전력수요에 미치는 영향을 검토하는 것이 중요하다. 본 논문에서는 이들 PHEV와 PBEV 자동차의 보급으로 전력망의 전력수요, 이산화탄소 배출량과 차량구매자의 관점에서 운전비용에 미치는 영향을 분석하였다. 2020년경에 차량보급이 10%정도로 이루어질 것을 가정하여 영향을 분석하였다.

• 환경영향평가
• /
• 제16권4호
• /
• pp.251-265
• /
• 2007

In this study, the influence of the construction of a large sized building on the flow and level of groundwater in a metropolitan area was investigated with simulation model MODFLOW for a selected area located in Gangseo-gu, Seoul, where a large business center was scheduled to be built. It was simulated that the groundwater level in the study area was suddenly lowered by the construction of a large building and groundwater in the surrounding area fast flowed into the study area. And even after the construction finished, the falling down of groundwater level consistently continued in some degree. The flow state of groundwater appeared to be the same in both cases where a soil cement wall is applied and where it is not during the construction. But for the case of application of a soil cement wall as the amount of groundwater flowing into the study site became reduced, it was estimated that the time for underground watershed getting far away from the site was also reduced and the influence of a building construction on the surrounding groundwater became reduced. Thus, it is deemed necessary that recharging the spilled ground water and rainfall into the construction area to lessen the abrupt change in flow and level of ground water should be considered in design of construction of a large sized building in a metropolitan area.

• 한국농공학회논문집
• /
• 제53권6호
• /
• pp.67-74
• /
• 2011

The objective of this study was to compare concentrations of nutrients such as total nitrogen (TN), nitrate nitrogen ($NO_3$-N) total phosphorous (TP), and phosphate phosphorous ($PO_4$-P) in groundwater under paddy and upland fields, and surface water recharging from a rural mixed land-use watershed. Chinese cabbage and hot pepper were cultivated on the upland field plot. The TN concentrations in upland groundwater showed double peaks (4.7, 4.3 mg/L, respectively) in April 2009 shortly after fertilizer application, indicating that TN concentrations are greatly influenced by fertilization. However, the TN concentrations in paddy groundwater were always lower than 2.0 mg/L irrespective of fertilization. Whereas the mean concentrations of TN and $NO_3$-N in upland groundwater significantly (p<0.05) higher than those in surface water, the mean concentrations of TP and $PO_4$-P in upland groundwater were significantly lower than those in surface water. On the other hand, the mean concentrations of TN, $NO_3$-N, TP and $PO_4$-P in paddy groudwater were significantly (p<0.05) lower than those in surface water. The TN concentrations in upland groundwater were generally higher than those in surface water during early April to early December due to the effect of fertilization, but vice versa in the other periods. In contrast, the TP concentrations in upland groundwater were always lower than those in surface water due to the sorption of inorganic phosphorous by soil. Moreover, the TN and TP concentrations in paddy groundwater were always lower than those in surface water, and therefore paddy groundwater may dilute nutrient concentrations in surface water when paddy groundwater and surface water mix.