• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.26 no.5
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• pp.218-223
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• 2014

Korea District heating corp. recently give an attention to combine the district heating and supply pipes as a two pipe system that are in the present system separated with room heating and warm water supply pipe, and the two pipe system is commonly applied for heating service in European countries. In the new two pipe system, only one heat source is supplied to a house and partitioned into room heating and warm water supply by household substation. So the effective distribution of supplied heat source in accordance to user intention is very important. This paper presents the development and performance test of three-way proportional control valve for a combined heat source system in district heating. The proposed valve is controlled to partition heat source into two different directions : hot water distributor for space heating and household substation for warm water supply in response to the pressure drops of tap water caused by the user. The performance investigation is shown within 3% of error compared to the theoretical model of the three-way proportional valve and its controllability is verified.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.430-435
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• 2008

Total lengths of domestic pipe network for district heating system are above about 2,500Km. A lots of pumping power for heat transportation through long pipe are required by the flow friction of pipe surface. Until now there have been considered about various methods to reduce the flow friction for district heating system such as using surfactants and turbulence promoters by swirl flow and baffles etc. At this study, swirl flow generator was tested about the possibility to increase the heat transfer ratio at the heat exchanger in the case which the suppling water temperature increased from $50^{\circ}C$ until $120^{\circ}C$. Experimental results showed that the heat transfer ratio increased and also pressure increase ratio increased simultaneously in the case which swirl flow generator installed. The amount of the increasing ratio for heat transfer and pressure were reached until 4.33% and 11% at the case of $120^{\circ}C$ suppling temperature which domestic district heating system were using.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.637-642
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• 2008

The concept of district heating involves centralised heat production where heat is distributed to consumer via a piping network. The objective of this work is to identify the Flexible Pipe from an economy, execution, maintenance point of view. Flexible Pipe has in some countries, especially in Europe, been used for many years in district heating. In spite of years of experience, there still exist doubts about the possibilities of using flexible pipes in district heating applications, mostly because of no experiences in domestic market. The advantage of flexible pipe systems is their flexibility. This holds not only for the inner pipe but also for the total pipe system including insulation and jacket. Even for the largest diameter the minimum radius of curvature is given to 1.5m. The most important difference between flexible pipe systems and preinsulated steel pipes is their simple and quick assembly. Such information could provide a basis for making reasonable hypotheses about consumer preferences, to foam a basis for making future marketing more effective.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.825-832
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• 2008

A simulation program is developed for analysing thermal networking process between the District heating and the CES(Community Energy Supply) systems. The effects of thermal networking on the District heating facilities previously being operated are implemented using mathematical correlations in terms of the fuel consumption and energy load such as heating and electricity. The operational characteristics according to the prime movers is modeled based on the materials of efficiency as a function of operational load. The unit energy load model is also developed extensively for several building types such as apartment complex, hotel, hospital, buildings for business and commercial use respectively. The specific features of the newly developed program in simulation of thermal networking process in district heating is described in terms of the reliability and the easiness for operating it etc.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.663-668
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• 2008

This study was carried out solar heating system design for district heating and it's the performance analysis by experiment. This experimental system was installed in Bundang district heating area in the end of 2006. The flat plate and vacuum tube solar collector are combined in one system. So district heating water is heated first by flat plate solar collector and than by vacuum tube solar collector. This solar heating system has not a solar buffer tank and is operating with variable flow rate to obtain a setting temperature of $90{\sim}95^{\circ}C$. As a result, the daily solar thermal collection efficiency is about 30 to 40% for the plate type and 50 to 55% for the vacuum tube solar collector. It varied especially depend on the weather condition like as solar radiation and ambient temperature. This variable flow rate system can be also reduced much pumping power more than 50%.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2003.05a
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• pp.16-20
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• 2003

Recently, The fast change of fishing boat fishery surrounding environment is connected by request of fan shape development that meet in restructuring of existing fishing boat fishery and new community, economical surrounding. In southern sea district along the coast work and district along the coast fishing bats that sail to exposed propeller fishing net, rope etc.. cold real condition that accident is increasing every year. This study is thing which analyze main performance of minuteness water jet type district along the coast fishing boat through model examination to propeller protection tunnel sticking district along the coast fishing boat that correct existing stem shape for marine accident prevention of district along the coast fishing boat in viewpoint such as ideal and examines.

• Journal of Preventive Medicine and Public Health
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• v.31 no.4 s.63
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• pp.857-874
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• 1998

The objective of this study is to collect the opinions on the present condition and the improvement directions of urban health centers from and to make a comparison. Samples were drawn from the various sources of a district in seoul. 53 persons involved in district health's administration(the Members of a District Parliament, the senior officials of a District office, village chief) and 84 health center workers were surveyed with anonymous postal questionaires and 427 district private medical personnels with postal questionaires and 625 users of a health center with direct questionaires, from November 18 to 25, 1996. Additionally, 12,151 households were surveyed with self-reported questionaires including priorities on special district health services of health center, from September 1 to 7, 1996. The major findings were as follows : 1) Although the persons involved in district health administration tend to put lower priority on health service over other community activities, they well acknowledged the importance of health center. But health center workers strongly acknowledged the importance of both health service and heath center. 2) As to the level of human resoureces, equipments and ammenities of Health Center commpared with private medical institute, the persons involved in district health's administration and health center workers responded that health center was higher in following order : 54.9%, 41.6%, 36.5% and 88.0%, 80.7%, 44.1%. 3) Concerning the priorities of health center's improvement, the persons involved in district health's administration replied in the order of reinforcement of proffesional health workers (43.3%), improvement of equipments and ammenities(28.3%), and the health center workers replied in the order of reconstruction of organization(24.1%), public health education and promotion(22.8%), reinforcement of proffesional health workers(21.0%). 4) Both the persons involved in district health's administration and health center workers replied that Ministry Health and Welfare, District office, health center were essential as the most critical organizations in the activation of Health Center's Function. 5) Persons involved in district health's administration and health center workers chose, as the most important health center's Function, medical treatment and prevention of infectious disease, and prevention of acute and chrone disease control and special district health service, respectively. Both Groups replied that fammily planning and parasite control are no longer in need. 6) As the future health service requiring reinforcement, every human resources parties considered health conselling, health line, sex education as the most imortant elements in public health education. Concerning the reinforement of other health services such as medical checkup and visiting nurses, every human resources parties showed more than 80% approval rate, but for oriental medical care service, the private medical personels showed relatively low approval rate(52.9%). Therefore the planning for reinforcement of health center's function requires the reflection of human resources party's opinion and the implication of system which can control and combine the differences in party's opinions.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2008.04a
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• pp.143-148
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• 2008

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 1996.10a
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• pp.3-6
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• 1996

On July 12, 1993, a large earthquake (M=7.8) occurred off the south-west of Hokkaido, Japan. The tsunami generated by this earthquake caused a disaster which took a heavy toll of lives, more than 200 persons dead, by the flooding of tsunami in the area of Aonae district in Okushiri island. Investigation after the disaster made clear that southern lowland was flooded by the tsunami coming from west about 5 min after the shock and the second tsunami from the east attacked eastern lowland of the Aonae District about 10 min after the shock. (omitted)

• Proceedings of the SAREK Conference
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• 2007.06a
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• pp.159-159
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• 2007