• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 전력전자학술대회 논문집
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• pp.58-62
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• 2001

Photovoltaic and wind power generation have an advantage of unlimited and unpolluted amount of energy resource. In conventional wind generation systems, since the blade rotates at low speed when the velocity of wind decreases their operations are possible only under limited conditions. Therefore they are in trouble of self-generation without the help of auxiliary generation devices outside. The system driven by the wind force in this paper consists of a generator, an invertor, batteries and sets for power storage with a spring. In this paper, the operation characteristics of system were analyzed through experiments for a trial product.

• 설비공학논문집
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• 제17권5호
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• pp.410-417
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• 2005

The cooling performance of a transcritical $CO_{2}$ cycle varies significantly with a variation of refrigerant charge amount. In this study, the performance of the $CO_{2}$ system was measured and analyzed by varying refrigerant charge amount at a standard test condition. Besides, the losses of the major components in the $CO_{2}$ system were estimated by evaluating entropy generation with refrigerant charge amount. The losses in the expansion device and the gascooler show the major portion of the total loss. For undercharging conditions, the expansion loss dominates the overall system performance, while the gascooler loss increases significantly with an increase of refrigerant charge amount.

• 정보처리학회논문지:컴퓨터 및 통신 시스템
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• 제5권10호
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• pp.353-360
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• 2016

여러 개의 태양전지들이 붙어 있는 태양광 패널을 이용하여 전력을 생산하는 태양광 발전은 최근 신재생 에너지 기술로 빠르게 성장하고 있는 분야이다. 하지만 태양광발전의 단점 중 하나인 불규칙한 전력 생산문제로 인해, 장비 및 패널 결함에 빠르게 대응하지 못하는 문제가 발생한다. 이 연구에서는 다양한 기후데이터와 패널 정보를 이용하여 태양광발전량 예측 방법들을 비교하여 최적의 예측 알고리즘을 평가하고 이를 기반으로 태양광발전소 결함 검출 시스템을 개발하여 국내 태양광 발전소에 적용한 사례를 기술한다.

• 전기학회논문지
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• 제63권4호
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• pp.455-460
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• 2014

South Korea's power consumption is increasing every year. For stable electric power supply, more generation facilities are needed. But it is not easy to build nuclear power generation facilities, so provision of renewable energy is thought of as the solution. For the system's stable management, practical use of energy storing system is needed. Currently, pumping up electric power station is considered most useful. In this study, we have calculated the least amount of energy storing device by considering the renewable energy, HVDC, and change in power for the appliance of ESS in Jeju system, according to The 6th Basic Plan for Long-term Electricity Supply and Demand. Also we have calculated the amount of the battery and about the load equalizing effect to use battery as power storing device. Finally, we have calculated the reduction of electricity generation and the reduction of $CO_2$ emission with this study.

• 대한기계학회논문집B
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• 제27권10호
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• pp.1442-1449
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• 2003

We investigated the amount of the toxic gases emitted from the Electrostatic Precipitators(ESPs), which are currently used as the indoor air cleaners. The existing wire-to-plate(WTP) and neddle-to-plate(NTP) types of ESP designs are considered as the experimental corona dischargers. Using the voltage, the polarity of wire, the number of needles of NTP as the input variables, we studied the generation characteristics of ozone and $NO_{x}$ and the particle removal efficiency in the ESPs. As the results, we found out that the concentration of ozone, $NO_{2}$ and $NO_{x}$ is increased with increasing the voltage and the number of needles, but the amount of NO is decreased. And we observed that the generation rates of ozone and $NO_{x}$ are mainly related with the corona region through the photographs. Finally the experimental results showed that the particle removal efficiency of ESP with WTP type charger is more superior to that with NTP type chargers at the same voltage.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.109.2-109.2
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• 2011

A photovoltaic system is getting the spotlight for a environment-friendly energy source. But its location is limited because a lot of land is necessary for photovoltaic arrays. Nevertheless, its dissemination is rapidly increasing more than 40 % every year and exceeded about 400 MW in 2009. The radical growth of a photovoltaic system aggravated a lack of sites, so that forests and farmland were destroyed. It is demanded to make use of a vacant lot or little piece of land for the way to solve the lack of sites and improve the location requirements for a photovoltaic system. General photovoltaic arrays are consist of a single layer structure and needs enough separation distances to maximize the amount of solar radiation and to eliminate influences by the shadow of other arrays. So that a large amount of land is required for the site. The solar cell arrays with long separation distances can not be placed in a small vacant lot and its site application efficiency is low. This study optimized photovoltaic arrays as multilayered structure with movable sleeves for the efficient photovoltaic in a small site. The existing photovoltaic arrays with a single layer structure were fixed or tracking systems. In this experimental equipment, photovoltaic arrays attached to the multilayers have rectilinear movement and rotary motion using sleeves. Therefore, shadow influences were removed and the generation capacity was improved. On the simulation result, generation increased by about 30% in the same site considering shadow influences and so on.

• 한국유체기계학회 논문집
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• 제20권2호
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• pp.69-74
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• 2017

Sodium hypochlorite, used as water disinfectant, is generated by electrolysis of salt. Compared to chlorine gas disinfection, it is free from high-pressure gas regulation and does not generate toxic gas, so it is increasingly used as a safe disinfectant. Despite these advantages, the concentration of sodium hypochlorite decreases with temperature during long-term storage, and the amount of chlorate increases when a large amount is added, it has mainly been applied to small-scale waterworks. To solve this problem, high sodium hypochlorite generation was developed. In this study, the changes of concentration and chlorate of sodium hypochlorite with time has been studied. As a result of the test, it was found that the usable period of sodium hypochlorite produced at a certain temperature or less was increased from 1.5 days to 13 days. Overall, sodium hypochlorite can be applied even in large-scale waterworks, which makes operation more stable and also reduces the disinfection byproducts, thus it contributed greatly to securing water quality.

• 한국유체기계학회 논문집
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• 제11권3호
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• pp.22-29
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• 2008

Clean and renewable energy technologies using ocean energy give us non-polluting alternatives to fossil and nuclear-fueled power plants to meet establishment of countermeasures against the global warming and growing demand for electrical energy. Among the ocean energy resources, wave power takes a growing interest because of its enormous amount of potential energy in the world. Therefore, various types of wave power conversion system to capture the energy of ocean waves have been developed. However, suitable turbine type is not normalized yet because of relatively low efficiency of the turbine systems. The purpose of this study is to investigate the internal flow and performance characteristics of a cross-flow type hydro turbine, which will be built in a caisson for wave power generation. Numerical simulation using a commercial CFD code is conducted to clarify the effects of the turbine rotation speed and flow rate variation on the turbine characteristics. The results show that the output power of the cross-flow type hydro turbine with symmetric nozzle shape is obtained mainly from Stage 2. Turbine inlet configuration should be designed to obtain large amount of flow rate because the static pressure and absolute tangential velocity are influenced considerably by inlet flow rate.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2015년도 학술발표회
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• pp.219-219
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• 2015

Hwacheon Reservoir is one of the reservoirs, which are located on the North Han River in South Korea. Construction of this reservoir was started in 1939 and completed in 1944. At the upstream of this reservoir there are Peace Reservoir, which is located in South Korea and Imnam Reservoir, which is located in North Korea. After construction of Imnam Reservoir, inflow regularity of Hwacheon Reservoir was changed and inflow of Hwacheon Reservoir also, was decreased. Peace Reservoir is used to decrease flood and damage at downstream due to unexpected release from Imnam Reservoir. This reservoir also, has a special role to regulate inflow of Hwacheon Reservoir. Hwacheon Reservoir has an important role for hydropower generation and flood control. Capacity and maximum discharge capacity of Hwacheon Reservoir are 1018 million $m^3$ and $9500m^3/s$, respectively. This reservoir has four generators to produce power and it is one of the important reservoirs for hydropower generation in South Korea. Due to the important role of this reservoir in generating power, maximization of hydropower generation of this reservoir is important and necessary. For this purpose, HEC-ResPRM model was applied in this study. HEC-ResPRM is a useful and applicable model to operate reservoirs and it gives optimal value for release to maximize power by minimizing penalty functions. In this study, after running the model, amount of release was optimized and hydropower generation was maximized by allocating more water for hydropower release instead of spillway release. Also, the model increased release in dry period from October to June to prevent high amount of release in flood season from July to September.

• 한국전자통신학회논문지
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• 제17권5호
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• pp.825-832
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• 2022

본 논문은 영농형 태양광 발전 시스템의 전력 생산량을 수집·저장하여 지능적인 예측 모델을 구현하기 위한 예측 및 진단 모델의 설계와 구현에 대해 논한다. 제안된 모델은 시계열 데이터에 특화된 순환신경망 기법인 RNN, LSTM, GRU 모델을 이용하여 태양광 발전량을 예측하고 각 모델의 하이퍼 파라미터를 다르게 주어 비교 분석하고, 성능을 평가했다. 그 결과 세 모델 모두 MSE, RMSE 지표는 0에 매우 가까우며, R2 지표는 1에 가까운 성능을 보였다. 이를 통해 제안하는 예측 모델은 태양광 발전량을 예측하기에 적합한 모델임을 알 수 있고, 이러한 예측을 이용하여 영농형 태양광 시스템에서 지능적인 운영관리 기능에 적용될 수 있음을 보였다.