• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.781-783
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• 2005

직접부하제어를 효율적으로 운용하기 위해서는 우리나라의 계통상황을 면밀히 분석하여 전력수급의 비상시에 부하차단이 필요한 지역과 필요 없는 지역에 대한 판단이 필수적이다. 계통에서 요구되는 부하 차단량을 산정하기 위해서는 현재의 계통상황과 미래의 계통의 변화를 면밀히 관찰해야 하며 이를 효과적으로 확보하기 위한 명확한 시행절차가 필요하다. 하지만 현재 직전부하제어를 위한 약정체결은 한국전력공사와 에너지 관리공단에서 각자 진행하는 이원화 시스템으로 구축되어 있다. 그래서 본 논문은 2002년부터 2004년까지 두 기관의 약정체결 현황과 부하특성을 파악하고 분석하였다. 이 결과는 향후 직접부하제어의 최적부하배분 알고리즘 수립에 적용될 것이며 또한 향후 직접부하제어 약정부하의 신규발굴과 약정체결에 있어 참고자료가 될 수 있을 것이다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.627-629
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• 2003

직접부하제어사업은 전력산업구조개편에 따라 발생할 수 있는 공급자원의 불확실성에 대비한 강력한 수요관리프로그램 중의 하나로 정부에서 중점 추진중인 사업이다. 이미 선진국에서도 다양한 메커니즘에 의해 Demand Response Program과 같은 부하관리프로그램을 운영하여 전력수급 및 전력요금 안정화를 꾀하고 있다. 우리나라의 경우 2001년도부터 동사업이 시행되고 있으며, 이에 주관기관으로서 에너지관리공단에서 추진하고 있는 직접부하제어를 위한 시스템 구성 및 운용방안에 대해 언급하고자 한다. 직접부하제어시스템은 크게 2단계로 구분되어지며, 상위시스템은 에너지관리공단에 설치 운영 중인 "전력부하관리센터(LMC)"와 민간 참여에 의해 운영 예정에 있는 "부하관리사업자시스템 (LSES)"으로 구성되며, 하위시스템은 "수용가용 직접부하제어시스템"으로 구성된다. 이에 본 연구에서는 직접부하제어시스템의 제어명령 체계 및 계량/정산을 위한 데이터처리방식 둥을 제시하여 본 시스템의 유용성 및 발전방향을 도출하고자 한다.

• 한국산학기술학회논문지
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• 제9권5호
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• pp.1154-1163
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• 2008

배전자동화시스템(DAS:Distribution Automation System)과 변전자동화시스템(SCADA:Supervisory Control And Data Acquisition)은 전력계통을 컴퓨터와 통신기술을 이용하여 운용하는 주된 시스템으로, 현재 독립적으로 운영됨으로 인해 신속하게 처리되어야 하는 고장처리 및 활선작업처리가 지연되는 등의 문제점이 제기되어왔고, 이에 따라 DAS-SCADA 연계 연구가 요구되었다. 연계방법으로 직접연계, 웹연계, DAS 기능부 전력량계를 이용한 연계가 2005년 11월부터 2007년 12월까지 한전 사업소에서 시범 운영되었고, 그 결과 투자비용 면에서 직접연계방법이 웹연계 방법에 비해 약 1.3배 높지만 다양한 변전소 운전정보 전달의 신속성, 제어기능 우수 등의 타당성이 입증됨으로써 직접연계방법에 의한 DAS-SCADA 연계가 2010년까지 한전 사업소에 전국적으로 확대 적용될 계획이다. 시범 운영시 제기된 문제점을 개선하기 위해 변전소 개체별 통신 방법을 이용한 데이터 연계방안으로 개선하여 연계DB 자동구축 기능 및 연계시스템 진단/Log 기능을 개발하였다. 연계데이터 포인트와 통신데이터 종류를 정의하고, SCADA HMI 프로그램을 개발하여 변전소 단선도 자동생성 기능, 변전소 단선도 수동편집 기능, SCADA 감시 제어기능 및 이력관리 기능을 개발하였다. DAS-SCADA 연계시 정전건당 평균시간을 약 33% 단축하여 전력공급 신뢰도를 향상하고, 배전 계통운영센터와 변전소간 활선작업 처리절차 축소로 전력계통 효율적 운영에 기여하고, 나아가 고장시 부하절체 자동처리로 완전한 배전자동화 실현 및 해외 수출화 사업에도 크게 기여할 것으로 기대된다.

• 벤처혁신연구
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• 제5권2호
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• pp.85-99
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• 2022

시판되고 있는 실험용 및 산업용 건조기는 일반 드라이오븐, 열풍 순환 건조기, 진공건조기, 동결건조기 등으로 구분되고 기능, 크기 및 용량 등에 따라 그 종류도 다양하다. 그러나 제품의 품질 제어 및 성능 개선을 위해 중요한 요소인 수분측정이 적용되지 않아 현재는 건조 종료 후 임의로 중량을 칭량하기 때문에 매우 수동적이다. 일반적으로 수분을 측정하기 위한 방법은 직접적인 측정법과 간접적인 측정법으로 구분되고 수분 분리 전.후의 질량 또는 부피 변화와 같은 직접적인 측정법이 주로 이용된다. 상대적으로 열전도도, 마이크로파 등과 같은 간접적인 측정법은 측정 장비를 활용하기 때문에 적용이 제한적이다. 본 연구에서는 오픈소스 기반의 아두이노를 이용하여 비교적 손쉽게 수분측정 시스템을 설계하여 외부 환경요인에 영향 받지 않고 수분 변화량 및 무게 변화를 실시간으로 모니터링 하였다. 구체적으로 수분 민감도 물질 및 식품 건조에 적합한 60℃와 80℃에서 작동할 수 있는 온.습도 및 로드셀 측정 센서를 건조기 내부에 패키징하여 각종 변화량을 측정하였다. 또한 바나나, 배, 톱밥의 유기 시료를 이용한 반복적인 실험을 통해서도 건조시간 및 온도에 따른 증발율 변화와 로드셀 측정값에 있어 안정적인 응답특성을 나타냄으로써 성능 안전성을 확보할 수 있었다. 향후 온.습도 범위의 확대와 CFD(Computational Fluid Dynamics) 프로그램과의 비교 분석을 통해 신뢰도를 더욱 향상시킬 수 있을 것으로 판단된다.

• 한국지열·수열에너지학회논문집
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• 제18권4호
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• pp.12-21
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• 2022

Steam assisted gravity drainage(SAGD) is a process that drills well in the underground oil sands layer, injects hightemperature steam, lowers the viscosity of buried bitumen, and recovers it to the ground. Recently, direct contact steam generator(DCSG) is being developed to maximize steam efficiency for SAGD process. The DCSG requires high technology to achieve pressurized combustion and steam generation in accordance with underground pressurized conditions. Therefore, it is necessary to develop a combustion technology that can control the heat load and exhaust gas composition. In this study, process analysis of high-pressurized DCSG was conducted to apply oxygen enrichment technology in which nitrogen of the air was partially removed for increasing steam production and reducing fuel consumption. As the process analysis conditions, methane as the fuel and normal air or oxygen enriched air as the oxidizing agent were applied to high-pressurized DCSG process model. A simple combustion reaction program was used to calculate the property variations for combustion temperature, steam ratio and residual heat in exhaust gas. As a major results, the steam production efficiency of DCSG using the pure oxygen was about 6% higher than that of the normal air due to the reducing nitrogen in the air. The results of this study will be used as operating data to test the demonstration device.

• 지역사회간호학회지
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• 제14권2호
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• pp.190-199
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• 2003

This study was conducted to determine the factors affecting job satisfaction in workers by using the Job Stress Model proposed by the National Institute for Occupational Safety and Health (NIOSH). Data were collected from December 1 to December 30, 1999. The subjects were 2,133 workers employed at 155 work sites, who were examined using NIOSH Job Stress questionnaire translated by the Korea Occupational Safety ${\pounds}|$ Health Academy and Occupational Safety ${\pounds}|$ Health Research Institute. SAS/PC program was used for statistical analysis using descriptive analysis. Pearson's correlation coefficient, ANOVA, and Stepwise multiple regression analysis. The results of this study were as follows. 1. According to general characteristics of the subjects, job satisfaction was high in those with less number of children. 2. By work condition, job satisfaction was higher in those who were working in a permanent job position, were working with regular time basis than with shift basis, were working in regular shift hours than in changing shift hours, were working for a short period, and were working less hours and overtime works per week. 3. In terms of physical work environment, job satisfaction was significantly related to 10 physical environmental factors. In other words, job satisfaction was high in workers who were working in an environment with no noise, bright light, temperature adjusted to an appropriate level during summer and winter, humidity adjusted to an appropriate level. well ventilation, clean air, no exposure to hazardous substance during work hour, overall pleasant work environment and not crowded work space. 4. By work-related factors, job satisfaction was high in those with less ambiguity about future job and role, high job control/autonomy, and less workload. On the other hand, job satisfaction was low in those with little utilization of competencies, and much role conflict at work and workload. 5. As for the relationships between job satisfaction and the non-work related factors, job satisfaction was high in workers who were volunteering at different organizations or active in religious activities for 5-10 hours per week. 6. In the relationships between job satisfaction and buffering factors, significantly positive correlations were found between job satisfaction and factors such as support by direct superior, support by peers, and support by spouse, friend and family. 7. There were nine factors that affected job satisfaction in the workers: age, number of children, work hours per week, noise, temperature at the work site during summer, uncomfortable physical environment, role ambiguity, role conflict, ambiguity in job future, work load, no utilization of competencies and social support from direct supervisor. These nine factors accounted for 26% of the total variance in the multiple regression analysis. In conclusion. the following are proposed based on the results of this study. 1. The most important physical environmental factors affecting job satisfaction in workers were noise, role ambiguity, and work load, suggesting a need to develop strategies or programs to manage these factors at work sites. 2. A support system that could promote job satisfaction is needed by emphasizing the roles of occupational health nurses who may be stationed at work sites and manage the factors that could generate job stress. 3. Job satisfaction is one of the three acute responses to stress proposed in NIOSH job stress model (job satisfaction. physical discomfort and industrial accidents). Therefore, further studies need to be conducted on the other two issues.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2015년도 학술발표회
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• pp.237-237
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• 2015

The district of Marlborough has had more than its share of river management projects over the past 150 years, each one uniquely affecting the geomorphology and flood hazard of the Wairau Plains. A major early project was to block the Opawa distributary channel at Conders Bend. The Opawa distributary channel took a third and more of Wairau River floodwaters and was a major increasing threat to Blenheim. The blocking of the Opawa required the Wairau and Lower Wairau rivers to carry greater flood flows more often. Consequently the Lower Wairau River was breaking out of its stopbanks approximately every seven years. The idea of diverting flood waters at Tuamarina by providing a direct diversion to the sea through the beach ridges was conceptualised back around the 1920s however, limits on resources and machinery meant the mission of excavating this diversion didn't become feasible until the 1960s. In 1964 a 10 m wide pilot channel was cut from the sea to Tuamarina with an initial capacity of $700m^3/s$. It was expected that floods would eventually scour this 'Wairau Diversion' to its design channel width of 150 m. This did take many more years than initially thought but after approximately 50 years with a little mechanical assistance the Wairau Diversion reached an adequate capacity. Using the power of the river to erode the channel out to its design width and depth was a brilliant idea that saved many thousands of dollars in construction costs and it is somewhat ironic that it is that very same concept that is now being used to deal with the aggradation problem that the Wairau Diversion has caused. The introduction of the Wairau Diversion did provide some flood relief to the lower reaches of the river but unfortunately as the Diversion channel was eroding and enlarging the Lower Wairau River was aggrading and reducing in capacity due to its inability to pass its sediment load with reduced flood flows. It is estimated that approximately $2,000,000m^3$ of sediment was deposited on the bed of the Lower Wairau River in the time between the Diversion's introduction in 1964 and 2010, raising the Lower Wairau's bed upwards of 1.5m in some locations. A numerical morphological model (MIKE-11 ST) was used to assess a number of options which led to the decision and resource consent to construct an erodible (fuse plug) bank at the head of the Wairau Diversion to divert more frequent scouring-flows ($+400m^3/s$)down the Lower Wairau River. Full control gates were ruled out on the grounds of expense. The initial construction of the erodible bank followed in late 2009 with the bank's level at the fuse location set to overtop and begin washing out at a combined Wairau flow of $1,400m^3/s$ which avoids berm flooding in the Lower Wairau. In the three years since the erodible bank was first constructed the Wairau River has sustained 14 events with recorded flows at Tuamarina above $1,000m^3/s$ and three of events in excess of $2,500m^3/s$. These freshes and floods have resulted in washout and rebuild of the erodible bank eight times with a combined rebuild expenditure of $80,000. Marlborough District Council's Rivers & Drainage Department maintains a regular monitoring program for the bed of the Lower Wairau River, which consists of recurrently surveying a series of standard cross sections and estimating the mean bed level (MBL) at each section as well as an overall MBL change over time. A survey was carried out just prior to the installation of the erodible bank and another survey was carried out earlier this year. The results from this latest survey show for the first time since construction of the Wairau Diversion the Lower Wairau River is enlarging. It is estimated that the entire bed of the Lower Wairau has eroded down by an overall average of 60 mm since the introduction of the erodible bank which equates to a total volume of $260,000m^3$. At a cost of $$0.30/m^3$ this represents excellent value compared to mechanical dredging which would likely be in excess of $$10/m^3$. This confirms that the idea of using the river to enlarge the channel is again working for the Wairau River system and that in time nature's "excavator" will provide a channel capacity that will continue to meet design requirements.