• Journal of Energy Engineering
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• v.6 no.2
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• pp.176-187
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• 1997

As a way to evaluate the performance of IGCC (Integrated Gasification Combined Cycle) processes, heating values of coal gas as well as plant efficiency were compared for different rank coals and coal feeding methods by employing the static process simulation technique. Performance of the process was compared with coal rank that was varied by three assorted bituminous coals and also by three subbituminous coals, in addition to the two types of feeding techniques, i.e., dry-feeding and slurry-feeding, that are utilized in entrained-bed coal gasifiers. For the verification of the simulation technique, simulated results were compared first with the actual pilot plant data published from Shell and Texaco. The simulation technique was, then, applied to other coals. Result from tests varying coal rank exhibits the trend of improving both heating content of the product gas and plant efficiency with increasing carbon content in coal. The effect of coal rank is more sensitive in slurry-feeding cases compared to the dry-feeding cases. In particular, considering notably lower values in gas heating value and plant efficiency calculated in the slurry-feeding case that uses a subbituminous coal, limited utilization of the slurry-feeding method for subbituminous coals can be expected. From the plant efficiency point of view, dry-feeding method resulted in higher simulated efficiency values by maximum 3% for subbituminous coals and ca. l% for bituminous coals.

• Proceedings of the KIEE Conference
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• 2006.07e
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• pp.39-40
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• 2006

가스절연개폐장치(GIS: Gas Insulated Switchgear) 내부에서 발생하는 UHF 부분방전 신호를 측정하고, 이를 주파수 분석을 통하여 1차 부분방전 진단을 수행하며, 주요 이상이 있을 경우 위상 분석을 통하여 7가지의 부분방전 패턴으로 분류하여 부분방전 원인을 진단할 수 있는 GIS 부분방전 진단 시스템을 국산화 개발하였다. 이에 본 논문에서는 주파수 분석방법, 부분방전 진단 패턴 및 모니터링 시스템에 대하여 기술한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.9
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• pp.1771-1776
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• 2017

Recently, IoT(Internet of Things) has been utilized in various fields provide a service to users by configuring a smart environment in a particular place. However, since the existing system does not change the operation and the task of the device according to the change of the surrounding environment, the user must operate passively every time the environment and the situation change. In this paper, we propose Situation-specific Task Control System based on real-time data classification. Sensor data is sent to the server and classified into real-time and non-real-time data, and then inserted into the decision tree to identify tasks according to the situation. In addition, the danger situation is divided into two stages, such as gas leakage and fire, and a warning message is sent. Therefore, it is possible to reduce the waste of electric power and the occurrence of malfunction, and it can be expected that the service with increased work efficiency will be provided.

• Environmental and Resource Economics Review
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• v.25 no.4
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• pp.565-590
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• 2016

In accordance with the global efforts to reduce greenhouse gas emissions, Korean government submitted its INDC (Intended Nationally Determined Contribution) of 25.7% for domestic reduction and the total of 37% reduction by 2030 including the purchase of emission reduction permit from abroad. In this study, 25.7% reduction target is being evaluated to see its impact on domestic energy system using the integrated assessment model, GCAM (Global Change Assessment Model). Results show that electricity generation from fossil fuel technologies using coal and gas decrease by 28.0%, 13.5% while that of biomass, wind power, solar energy increase by 47.6%, 22.0% and 45.4%, respectively. It is worth noting that so called new technology such as USC (ultra supercritical power generation) does not contribute to achieving the emission reduction target and careful and quantitative analysis is required for such categorization in the future.

• Journal of the Korean Institute of Gas
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• v.21 no.1
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• pp.6-17
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• 2017

Objectives : The purpose of this study was to obtain information regarding Globally Harmonized System(GHS) classification and health hazards that may result from a 4 weeks inhalation exposure of 3-Methylpentane in Sprague-Dawley rats. Methods : The testing method was conducted in accordance with OECD guidelines for the testing of chemicals No. 412(Subacute Inhalation Toxicity). The Rats were divided into 4 groups(5 male and 5 female rats in each group) and exposed to 0 ppm, 284 ppm, 1,135 ppm, 4,540 ppm 3-Methylpentane in each exposure chamber for 6 h/day, 5 days/week, for 4 weeks. After two weeks, the test animals were autopsied and carried out blood test and biochemical tests and histopathological examination. We used PRISTIMA (Toxicology data management system) to confirm the system and to have confidence of the raw data. Results : No death and particular clinical presentation including weight change and change of feed rate was observed. Relationship between dose, gender and response was also not significantly changed in hematologic examination, biochemical examination of blood and blood coagulation time. The histopathologic lesions caused by the test substance did not appear. Conclusions : NOAEL(No Observable Adverse Effect Level) of 3-Methylpentane is more than 4,540 ppm in male group and female group and the Ministry of Employment and Labor Guidance Announcement No. 2013-37(criteria for the classification marks and Safety of Chemicals) Specific target organ toxicity(repeated exposure) was determined with a substance that is not the separator material.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.317-324
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• 2020

Combined cycle power plants (CCPP) that use natural gas as fuel are easier to start and stop, and have lower pollutant emissions, so their share of domestic power generation facilities is steadily increasing. However, CCPP have a high concentration of nitrogen dioxide (NO2) emission in the initial start-up and low-load operation region, which causes yellow plume and civil complaints. As a control technology, the yellow plume reduction system was developed and operated from the mid-2000s. However, this technology was unable to control the phenomenon due to insufficient preheating of the vaporization system for 10 to 20 minutes of the initial start-up. In this study, CFD analysis and demonstration tests were performed to derive a control technology by injecting a reducing agent directly into the gas turbine exhaust duct. CFD analysis was performed by classifying into 5 cases according to the exhaust gas condition. The RMS values of all cases were less than 15%, showing a good mixing. Based on this, the installation and testing of the demonstration facilities facilitated complete control of the yellow plume phenomenon in the initial start-up.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.07a
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• pp.304-309
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• 2002

신선농산물의 호흡에 영향을 미치는 인자를 들면 품목의 종류, 품종, 숙도, 저장온도, 산소농도, 이산화탄소 농도 등이다. 산소농도와 이산화탄소농도는 신선 농산물의 호흡속도에 영향을 주는 외적인 요인으로 분류되며 이들 인자들은 제어하기가 용이하며 모델링을 통하여 함수관계를 도출할 수도 있다. 따라서 환경기체조성을 변화시킨 상태에서 측정된 신선농산물의 호흡속도자료는 포장 및 저장을 위한 중요한 물성특성치로 이용된다. (중략)

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.72-77
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• 2008

The function of the Reaction Control System include roll, pitch and yaw control of the launch vehicles and fine control maneuvers and precision upper stage orientation before separation of one or more payload. This paper describes the overview of commercial launchers, current technology trend for RCS of launch vehicles, and development status of medium class thruster for RCS.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.89-89
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• 2023

인간 활동에 의해 발생한 전 지구적 기후변화는 다양한 분야에 영향을 미치고 있다. 특히, 군락을 기반으로 서식하는 동식물은 기후변화에 가장 취약하며, 대부분의 군락 위치가 북상하거나 멸종 위기에 처해있다. 2022년에 발표된 IPCC(Intergovernmental Panel on Climate Change) 보고서는 섭씨 5도 이상 상승하면 생물군의 60%가 멸종될 것이라고 보고하였으며, 고위도와 고도로 이동하여 봄철 식물 성장이 과거보다 더욱 가속화 될 것으로 예측하였다. 따라서, 온실가스 농도에 따른 전 지구적 기후변화 분석은 다양한 분야에서 지속가능한 완화 및 적응 정책을 결정하는데 필요하다. 본 연구는 SSP2-4.5와 SSP5-8.5를 이용하여 Koppen-Geiger의 기후대 분류에 따른 전 지구 규모(아시아, 유럽, 남아메리카, 북아메리카, 오세아니아, 아프리카)의 과거 및 미래 기후대에 대한 변화를 분석하였다. 과거 기간의 기후대를 추정하기 위해 25개 CMIP6(Coupled Model Intercomparison Project 6) GCM(General circulation model)의 월 단위 강수량과 표면 온도를 사용하였으며 6개의 기간으로 구분하여 기후대 변화를 비교하였다. 더 나아가, 미래 기후대를 예측하기 위해 SSP(Shared Socioeconomic Pathways)2-4.5와 SSP5-8.5의 미래 기후변수를 사용하였으며, 전망 기간을 7개로 구분하여 전망 기간의 기후대를 변화를 비교하였다. 본 연구의 결과로는 온실가스 농도가 높은 시나리오에서는 북아메리카, 아시아, 유럽의 툰드라와 영구동토층이 가파르게 감소하였으며, 온대 기후 중 습한 아열대 기후대의 면적이 급속도로 증가하였다. 더 나아가, 남아메리카의 경우 대륙성 기후대가 지속적으로 감소하는 반면에 열대 우림 기후대는 증가한다. 오세아니아의 미래 기후대는 몬순의 영향을 받는 아열대 기후대가 증가하고 열대 우림은 증가할 것으로 예측하였다.

• Journal of the Korean Institute of Gas
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• v.27 no.2
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• pp.71-78
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• 2023

In general, electric submersible pumps (ESPs), which have an average life of 1.0 to 1.5 years, experience a decrease in performance and a reduction in life of the pump depending on oil and gas reservoir characteristics and operating conditions in wells. As the result, the failure of ESP causes high well workover costs due to retrieval and installation, and additional costs due to shut down. In this study, a flow loop system was designed and established to predict the life of ESP in long­term operation of oil and gas wells, and the life cycle data of ESP from the time of installation to the time of failure was acquired and analyzed. Among the data acquired from the system, flow rate, inlet and outlet temperature and pressure, and the data of the vibrator installed on the outside of ESP were analyzed, and then the performance status according to long-term operation was classified into five stages: normal, advice I, advice II, maintenance, and failed. Through the experiments, it was found that there was a difference in the data trend by stage during the long­term operation of the ESP, and then the condition of the ESP was diagnosed and the failure of the pump was predicted according to the operating time. The results derived from this study can be used to develop a failure prediction program and data analysis algorithm for monitoring the condition of ESPs operated in oil and gas wells.