• The KIPS Transactions:PartC
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• v.11C no.7 s.96
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• pp.923-930
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• 2004

Wireless sensor networks is a core technology of ubiquitous computing which enables the network to aware the different kind of context by integrating exiting wired/wireless infranet with various sensor devices and connecting collected environmental data with applications. However it needs an energy-efficient approach in network layer to maintain the dynamic ad hoc network and to maximize the network lifetime by using energy constrained node. Cluster-based data aggregation and routing are energy-efficient solution judging from architecture of sensor networks and characteristics of data. In this paper. we propose a new distributed clustering algorithm in using distance from the sink. This algorithm shows that it can balance energy dissipation among nodes while minimizing the overhead. We verify that our clustering is more en-ergy-efficient and thus prolongs the network lifetime in comparing our proposed clustering to existing probabilistic clustering for sensor network via simulation.

• Information and Communications Magazine
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• v.34 no.5
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• pp.61-67
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• 2017

CES(Community Energy System) 마이크로그리드 기술은 에너지 생산/공급 및 소비가 일정 지역에 구역화하여 공급하는 집단에너지사업 중 구역전기사업이 이루어지는 커뮤니티에너지공급(CES) 시설 환경을 기반으로 이루어지는 마이크로그리드 시스템 기술이다. 마이크로그리드 환경을 위하여 CES 시설 환경을 기반으로 신재생발전, ESS 등 분산자원을 추가하고, 내부 전력시스템 개선 및 신규 에너지 서비스 인프라가 추가로 구축된다. 아울러, 이를 기반으로 마이크로그리드 환경에서 제공될 수 있는 에너지 서비스를 제공한다. 본고에서는 이러한 CES 마이크로그리드 기술에 대해 기술하고 최근 이루어지고 있는 CES 마이크로그리드 기술 개발의 사례를 통해 새로운 비즈니스 모델을 찾아보고자 한다.

• Journal of Energy Engineering
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• v.18 no.1
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• pp.37-48
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• 2009

Recently, the significance of Green-Energy led by low-carbon Green-Development is increasing as well in Korea. Among them, the most practical solution is the cogeneration which performs the best energy efficiency. This paper addresses the two of RCS(Regional Cogeneration System) connecting heat each other. It is conducted to quantitatively evaluate algorithm that optimally operate the heat transaction considering various operating modes. The proposed method is tested using the real system. Through the case studies, it is verified that the proposed algorithm of heat transaction can evaluate availability.

• Journal of the Korean Solar Energy Society
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• v.31 no.5
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• pp.105-112
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• 2011

The purpose of this study was to analyze and compare the management group' and the teaching group' perception of energy education in Korea. For this purpose, this study carried out a questionnaire survey at schools participating in the energy saving policy. The data was collected from six managers and 171 teachers in middle schools. First, the results indicated that both the management group and teachers have a considerable interest in teaching energy saving practice. How ever the management group showed more preference toward teacher-leading courses, such as lecture, compared to the teachers Second, both the management group and teachers tended to take extracurricular activities. Third, the manager group mostly got energy educational resource from the teacher training program, textbook and teacher's companion. However the teachers mostly did from the mass media. Fourth, compared to the teachers, the managers preferred to allot more budgets to school facilities than to activities related to educating students related to energy. Fifth, the management group pointed out curriculum-making and more budget as the necessity to enhance energy education but the teaching groups did students' interest. Sixth, both the management group and teachers emphasis on the need of energy education.

• Phonetics and Speech Sciences
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• v.14 no.3
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• pp.87-101
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• 2022

In addition to administering a questionnaire (J-survey), which questions individuals on subjective vocal fatigue, voice samples were collected before and after speech-language pathology sessions from 50 female speech-language pathologists in their 20s and 30s in the Daejeon and Chungnam areas. We identified significant differences in Korean Vocal Fatigue Index scores between the fatigue and non-fatigue groups, with the most prominent differences in sections one and two. Regarding acoustic phonetic characteristics, both groups showed a pattern in which low-frequency band energy was relatively low, and high-frequency band energy was increased after the treatment sessions. This trend was well reflected in the low-to-high ratio of vowels, slope LTAS, energy in the third formant, and energy in the 4,000-8,000 Hz range. A difference between the groups was observed only in the vowel energy of the low-frequency band (0-4,000 Hz) before treatment, with the non-fatigue group having a higher value than the fatigue group. This characteristic could be interpreted as a result of voice abuse and higher muscle tonus caused by long-term voice work. The perturbation parameter and shimmer local was lowered in the non-fatigue group after treatment, and the noise-to-harmonics ratio (NHR) was lowered in both groups following treatment. The decrease in NHR and the fall of shimmer local could be attributed to vocal cord hypertension, but it could be concluded that the effective voice use of speech-language pathologists also contributed to this effect, especially in the non-fatigue group. In the case of the non-fatigue group, the rhamonics-to-noise ratio increased significantly after treatment, indicating that the harmonic structure was more stable after treatment.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2003.05a
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• pp.197-198
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• 2003

해양동물의 성장, 호흡 및 동화효율 등의 생태ㆍ생리적 연구는 에너지 흐름의 역학적 구조를 이해하고 생태계의 기능을 파악하는데 있어 유용한 수단이 된다. 생태계는 복잡한 먹이사슬과 같은 영양학적 구조와 집단간 에너지 흐름의 양에 밀접하게 관련되어 있으며, 이러한 복잡한 먹이망 속에서 그 물질의 전환에 따른 에너지 흐름을 파악하기 위해서 에너지 수지를 분석하는 것이 매우 중요하다 (Klekowski and Ducan, 1975). (중략)

• Korean Chemical Engineering Research
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• v.56 no.5
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• pp.655-662
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• 2018

To respond effectively to climate change following the launch of the new climate system, the government is seeking to expand the use of distributed power resources. Among them, the district heating system centered on Combined Heat and Power (CHP) is accepted as the most realistic alternative. On the other hand, the government recently announced the change of energy paradigm focusing on eco-friendly power generation from the base power generation through $8^{th}$ Basic Plan for Long-term Electricity Supply and Demand(BPE). In this study, we analyzed the quantitative effects of profit and loss on the CHP operating business by changing patterns of the heat production, caused by the change of energy paradigm. To do this, the power market long-term simulation was carried out according to the $7^{th}$ and $8^{th}$ BPE respectively, using the commercialized power market integrated analysis program. In addition, the CHP operating model is organized to calculate the power and heat production level for each CHP operation mode by utilizing the operating performance of 830MW class CHP in Seoul metropolitan area. Based on this, the operation optimization is performed for realizing the maximum operating profit and loss during the life-cycle of CHP through the commercialized integrated energy optimization program. As a result, it can be seen that the change of the energy paradigm of the government increased the level of the ordered power supply by Korean Power Exchange(KPX), decreased the cost of the heat production, and increased the operating contribution margin by 90.9 billion won for the 30 years.

• The Journal of the Korea Contents Association
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• v.15 no.7
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• pp.578-590
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• 2015

This paper investigated how high school students perceive on nuclear power applying semantic network analysis. The total number of 250 high school students in 6 metropolitan areas responded to the survey. Results indicate that the word which most frequently appeared is 'Nuclear plant' (87 times) following by 'Japan' (71 times), 'Danger'(59 times), 'Fukushima' (59 times), 'Radioactivity' (56 times), 'Energy' (47 times), 'Youngkwang' (37 times), 'Electricity' (30times), 'Chernobyl' (29 times), 'Explosion' (25 times). For students in higher acceptance level of nuclear 'Radioactivity' (25 times) was most frequently showed up following by 'Fukushima' (23 times), 'Energy' (21 times), 'Japan' (21 times), Nuclear plant' (20 times), 'Danger' (17 times), 'Youngkwang' (16 times). For student in lower acceptance level of nuclear, the word of 'Nuclear plant' (40 times) most frequently appeared following by 'Japan' (31 times)', 'Danger' (29 times), 'Fukushima' (23 times), 'Radioactivity' (17 times), 'Energy' (16 times), 'Youngkwang' (16 times), 'Chernobyl' (15 times).

• The Journal of Korean Institute for Practical Engineering Education
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• v.2 no.2
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• pp.42-48
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• 2010

For a basic engineering education Problem-Based Learning (PBL) method was adopted in order to pursuit the learner acquisition of critical knowledge, problem solving proficiency, and self-directed learning strategies by measurements of various physical and biological units, by calculation of errors in experimental data, by leraning energy conservation law and equation of motion, and, by analysis ability on data patterns through Elliptical Trainer(ET) exercise. The results show the ET may be a good experimental tool for understanding the PBL method. A sample syllabus was provided for one semester use, and by use of data obtained by self-directed and creative learning, the results of three groups for the PBL problems proposed by using ET were (1) the slope of angle was 23.5o in the diagram of energy exhaustion against velocity (GROUP A), (2) the angle range between the maximal and minimal energy exhaustion against weight loss was 15.0o ~ 26.5o (GROUP B), and finally (3) the angle was varied by 51.0o in the diagram of weight loss against distance (GROUP C).

• Proceedings of the Korea Air Pollution Research Association Conference
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• 1999.10a
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• pp.272-273
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• 1999

우리나라의 건축물은 국가에너지 소비의 상당한 비중을 차지하면서도 산업 및 교통분야에서처럼 효율적인 에너지 절약이 이루어지지 않는 문제점을 지니고 있다. 이처럼 건축물에 대한 에너지 절약이 잘 이루어지지 않는 가장 근본적인 원인은 건축물의 라이프 사이클이 다른 분야에 비해 매우 길고, 건축 각 분야들이 이해관계가 서로 다른 이질적 집단에 의해 이루어지기 때문이다. 즉 시공자, 건축주, 사용자 및 폐기업자 등이 개개의 운영비 절감을 위해서만 관심을 가질 뿐 건물의 Life Cycle에 대한 에너지, 환경부하 절감에는 크게 관심을 두지 않기 때문이다.(중략)