• Proceedings of the SAREK Conference
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.177-182
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• 2009

The purpose of this study is to investigate planning of urban energy supply systems configuration and operating conditions for the district heating and cooling system using combined heat and power system. Generally the district heating and cooling system has been known to one of the effective way for energy saving, cost reduction and demand side management of energy. Economical analyses were carried out and operating characteristics for some systems were examined in terms of GER factor which represents to the ratio of gas and electricity costs. Rates of the energy consumption and the $CO_2$ emission were compared from the system configuration of the energy supply system with new district cooling system with the conventional one.

• Journal of the Korean housing association
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• 제15권5호
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• pp.77-84
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• 2004

The mock-ups of ventilation system, which has been widely adopted for the bathroom with the area of 100 $m^2$ apartment housing, were established and tested to design mechanical ventilation for apartment housing bathroom where air supply exhaust are relatively important. These ventilation mock-ups were capable of controlling intake and exhaust, which has the size of supply openings as 40cm${\times}$1cm, 40cm${\times}$3cm, 40cm${\times}$5cm. They were established at five locations, spaced 40cm from each other at a height of 25cm from the floor. The exhaust fans were located at four corners and center of the ceiling. The results this ventilation effect measurement by different condition are showing that when the size of air supply is bigger and the location is lower, the effect of ventilation was relatively higher. In addition, as the distance between exhaust fan and air supply was farther, the ventilation effect were getting highly efficient.

• Proceedings of the KIPE Conference
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• 전력전자학회 2017년도 전력전자학술대회
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• pp.327-328
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• 2017

This paper presents the power supply system which is made of three units: the capacitor charging and main pulse unit, simmer power supply unit, and series trigger unit. The capacitor charging and main pulse unit charges the capacitor bank by using the series parallel resonant converter and the generated main pulses apply to the lamp. The series trigger unit ionize the xenon gas located in the lamp and the simmer power supply unit sustains the ionized condition. It means that the lamp lifetime and efficiency are advanced by reducing the number of triggering. Not only the operation of the proposed system but also the performance of each unit will be verified by the experimental results.

• The Journal of Asian Finance, Economics and Business
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• 제9권5호
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• pp.285-294
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• 2022

Using the ARDL approach, this study examined the impact of macro factors on Vietnam's stock market in the short and long run from 2010 to 2021. The State Bank of Vietnam and the International Monetary Fund provided time series data for this study. Research results show that in the long run, money supply and exchange rate respectively affect the stock market. The money supply had a positive effect on the VN-Index, while the exchange rate showed the opposite effect. However, the study did not find a relationship between world oil price and interest rates on VN-Index in the long run. On the other hand, in the short term, there are relationships between variables; specifically, interest rates and exchange rates have a negative impact on the VN-Index, while the world oil price and the fluctuation of money supply M2 of the previous one and two months showed an impact in the same direction on this index. The differences in the regression results on the impact of exchange rate and oil price on the VN-Index compared to previous studies come from the characteristics of Vietnam's stock market, with the large capitalization of companies in the oil and gas sector, and the structure of Vietnam's economy with export heavily depends on FDI sector.

• International conference on construction engineering and project management
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• The 6th International Conference on Construction Engineering and Project Management
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• pp.195-199
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• 2015

Many conventional management methods have emphasized the minimization of required resources along the supply chain. Accordingly, this paper presents a proposed method called the Virtual Design and Construction (VDC)-aided system. It is based on object-oriented resource control, in order to accomplish a feed-forward control monitoring supply chain logistics. The system is supported by two main parts: (1) IT-based Technologies; and (2) VDC Models. They enable the system to convey proactive information from the detection technology to its linked visualization. The paper includes a field study as the system's pre-test: the Scaffolding Works in a LNG Mega Project. The study demonstrates a system of real-time productivity monitoring by use of the RFIDbased Mobile Information Hub. The on-line 'productivity dashboard' provides an opportunity to display the continuing processes for each work-package. This research project offers the observed opportunities created by the developed system. Future work will entail research experiments aimed towards system validation.

• Journal of Navigation and Port Research
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• 제48권4호
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• pp.274-283
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• 2024

Climate change is currently one of the most pressing environmental issues, primarily caused by carbon emissions from fossil fuel usage. As a result, alternative fuels that effectively reduce carbon emissions are garnering more attention. Among these alternatives, hydrogen has numerous advantages, such as its ability for large-scale storage and transport. However, it is crucial to prioritize safety measures, particularly in facilities that handle hydrogen, due to its highly flammable and fast-spreading nature. This study aims to compare and analyze the placement of supply and exhaust vents to efficiently release hydrogen in the event of a leak in an enclosed space. The experiments involved six different scenarios, each with various combinations of supply and exhaust vents. To ensure the experimental process's safety, helium, which shares similar physical properties with hydrogen, was used to analyze the internal oxygen concentration during ventilation system operations. The results revealed that among the six scenarios, Case 2, which employed a lower side supply vent and an upper side exhaust vent, exhibited the shortest ventilation time of 4 minutes and 30 seconds. Additionally, the decrease rate in oxygen concentration was examined in the upper, middle, and lower areas. Ventilation utilizing an upper surface supply vent and two exhaust vents on the upper surface and upper side (Case 6), showed lower oxygen concentration values in the upper area, while Case 2 yielded lower values in the middle and lower areas. Therefore, it is crucial to select an appropriate supply and exhaust vent configuration considering the space's characteristics and usage environment.

• Transactions of the Korean hydrogen and new energy society
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• 제16권1호
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• pp.82-91
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• 2005

Polymer membrane needs to maintain appropriate moisture. Insufficient moisture causes low conduction of hydrogen ion because of increased contact resistance between electrode and membrane by shrinking membrane, and abundant moisture decreases fuel cell performance as difficulty of diffusion reacting gas. Therefore, water controlling system is very consequential for the polymer membrane fuel cell. If hollow fiber membrane humidification is used between fuel and air lines, it is possible to supply heat to fuel and air by using thermal exchanger. It can supply appropriate humidity depending on operating temperature, and can recover heat from exhaust gas which contains water vapor and air. Because of simple structure of humidification system, this system can be easily applied in the PEMFC and cut down cost.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제11권11호
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• pp.1043-1048
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• 1998

The decomposition performance of the Surface induced Plasma Chemical Processing(SPCP) for benzene, toluene, xylene and $NO_2$ were experimentally examined. Discharge exciting frequency range was 5kHz and 10kHz, and low frequency discharge requires high voltage to inject high electric power in gas and to decompose contaminants. The decomposition rate of dioxide nitrogen for 5kHz power in gas and to decompose contaminants. The decomposition rate of dioxide nitrogen for 5kHz power supply is only 85%, but it’s rate for 10kHz power supply is very high, more than 96% when peak voltage is 12kv. Aromatic hydrocarbon vapor of up to 1000ppm is almost throughly decomposed at the flow rate of 1000$\ell$/min or lower rate under the discharge with electric power of several hundred watts. High decomposition rate is shown in every case, that is, for SPCP reactor is necessary to obtain the decomposition rate of more than 80~98%. The decomposition rate of benzene, toluene and xylene were 90~98% and dioxide nitrogen was 45~96%.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• 제16권5호
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• pp.459-466
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• 2004

In order to save the energy in apartment houses, it is essential that the energy amount consumed in heating per household should be surveyed and analyzed according to heating method, which can be classified into unit, central and district methods. As a basis, we selected the household with nominal area of 32 py. because it accounts for the most percentage in Korea. It is estimated that the gas amount for cooking is 90 ㎥ and the energy amount for hot water supply is 11.41 GJ for a year, which is necessary to calculate the heating energy. Through the survey of actual energy consumption in Seoul and Gyeonggi, the energy amount used in heating can be obtained according to the heating type: 26.02 GJ/year for the unit heating, 28.09 GJ/year for the central heating and 40.61 GJ/year for the district heating.

• The KSFM Journal of Fluid Machinery
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• 제19권6호
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• pp.26-33
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• 2016

Combined heat and power (CHP) system is one of the power generation system which can generate both electricity and heat. Generally, mid-size and big-size CHP plant in Korea generate electricity from gas turbine and steam turbine, then supply heat from exhaust gas. Actually, CHP can supply heat using district heater which is located at low pressure turbine exit or inlet. When the district heater locates after low pressure turbine, which called back pressure type turbine, there need neither condenser nor mode change operating control logic. When the district heater locates in front of low pressure turbine or uses low pressure turbine extraction steam flow, which calls condensing type turbine, which kind of turbine requires condenser. In this case, mode change operation methods are used for generating maximum electricity or maximum heat according to demanding the seasonal electricity and heat.