• Journal of the Korean Solar Energy Society
• /
• v.30 no.6
• /
• pp.1-9
• /
• 2010

Apartment balcony has been remodeled since the government permitted remodeling in January 2006.But extended balcony has great impact on building heat gain and loss. Therefore It has problems such as increase of heating and cooling energy. So $\underline{t}echnical$ solutions about window solar gain in summer is an urgent matter. The Purpose of this study is to evaluate energy performance of a blind in a double-skin facade in residential buildings by using EnergyPlus program. The results show that slat angles of $90^{\circ}$ is best in energy performance if we do not consider daylight. Poorly daylighted living room needs electric light and it also causes high cooling load. On the other hand, the results show that the application of blinds controlled automatically is best for energy performance when we consider daylight. Blind slat angles of $50\sim60^{\circ}$ have best performance when blinds are controlled in this angle throughout the day on a clear day in August. Blind slat angles of $0\sim30^{\circ}$ have best performance when blinds $\underline{are\;controlled}$ in this angle throughout the day on a cloudy day (more than 7 of total sky cover) in August.

• Journal of the Korean Geotechnical Society
• /
• v.31 no.4
• /
• pp.5-12
• /
• 2015

The construction of waste landfill sites has been increased due to recent expansion of various waste. Geotextiles are widely used for the purpose of reinforcement and protection of waste inside the landfill. Geotextile affects the shear behavior of waste landfill which forms the contact surface with soil. In this study, the effect of acidic and alkaline components in leachate has been analyzed through the laboratory experiment on the shear stress reduction of the contact surface of ground-geotextile under the cyclic load. For this purpose, a dynamic contact surface shear tester has been manufactured, and cyclic simple shear tests have been performed using geotextile and soil specimen which were immersed in chemical solutions for 60 and 840 days, respectively. Based on the Disturbed State Concept, the characteristics of shear stress on the contact surface of ground-geotextile due to chemical factors have been identified by the disturbance function.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.10 no.2
• /
• pp.19-23
• /
• 2014

In the capital of Mongolia where the air quality is getting worse due to the coal consumption used for electricity generation and district heating, the application of geothermal systems in the housing sector is recently designed for high class resort. In this study, the case of applying a geothermal system in a house in Mongolia is examined. The effects of passive house design on the needed heat pump capacity, as well as the annual energy consumption are analyzed. Moreover, as the initial costs, except labor fee, are assumed similar to Korea, cost analysis for several cases is examined, too. From the results, if a house is designed according to passive house standard instead of ASHRAE standard, the heat pump capacity can be expected to be reduced from 16 to 5~6 RT. Furthermore, although the initial cost of architectural cost might increased by 29 M\, the total initial cost is reduced by 14 M\, while the annual energy consumption is reduced by 14%. This is mainly driven by the fact that the geothermal system which serves as the main system to cover the building needs, with a high initial cost for fulfilling the peak requirements.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.41 no.4
• /
• pp.249-256
• /
• 2017

Premixed combustion has many advantages, including low CO and NOx emissions and a small combustor volume. These characteristics allow a compact design and wide application to condensing boilers with high thermal efficiencies. This study focused on the combustion characteristics in a premixed combustion burner using metal fiber and a throttle body. The results showed that a blue flame was found to be very stable at a heating load of 6,250-25,000 kcal/h when implementing the proper metal fiber, baffle plate, and throttle body. The NOx emission was less than 11 ppm under an equivalence ratio of 0.724-0.795, and the CO emission was less than 50 ppm under the same equivalence ratio. The thermal efficiency, which is a very important index when condensing a gas boiler, was observed to be above 96.3％ under an equivalence ratio of 0.750.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.15 no.1
• /
• pp.90-97
• /
• 2001

A high frequency resonant inverter consisting of iliree unit Half-Bridge serial resommt inverter used as power source of induction heatmg at high frequency is presented in this paper. As a output [Dwer control strategy, sequencial time-sharing gate contml methcd is applied. This methcd is TDM(Time Division Multiplexing), which is broadly used with digital and analog signals transmission in communication system 1be analysis of the proposed circuit is generally described by using the normalized pararmenters. Also, the principle of basic operating and the its characteristics are estimated by the parameters such as switching frequency, load resistance. Also, according to the calculated characteristics value, a method of the circuit design and operating characteristics of the inverter is proposed. This paper proves the validity of theoretical analysis through the Pspice. This proposed inverter show that it can be practically used in future as power source system for induction heating application, DC-DC converter etc. r etc.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.40 no.6
• /
• pp.536-541
• /
• 2012

An instrumented pod has been developed to measure the aeroacoustic environment as well as the conventional data such as load, vibration, and aerodynamic heating of fighters during flight tests, confirming to the recently developed external pod design for fighters. This study presents the development of the measurement system in detail, being the first indigenous effort in its kind. The pod was designed to meet the requirements of the MIL-HDBK-1763 and MIL-STD-810 Method 515, which are the base to determine the locations and range of sensors. The Endevco 8510B-2 was selected as the sensor to withstand the harsh environment during the flight tests. In order to assess the integrity of the fabricated pod design, a ground run-up test of a KF-16 has been conducted with the pod installed at Station 5. The test results show that the system works well but the sound level exceeds the predetermined sensor range. The sensor range has been readjusted for flight test performed later.

• Proceedings of the KIEE Conference
• /
• 2007.07a
• /
• pp.210-211
• /
• 2007

Amid booming PV(photovoltaic) industry, BIPV(Building Integrated PV) is one of the best fascinating PV application technologies. To apply PV in building, variable factors should be reflected such as installation position, shading, temperature effect and so on. Especially a temperature should be considered, for it affects both electrical efficiency of PV module and heating and cooling load in building. Transparent PV modules were designed as finished material for spandrels are presented in this paper. The temperature variation of the modules with and without air gap and insulation were compared and analyzed. The results showed that the module with air gap and insulation has a much larger temperature variation than another transparent module. The temperature of the module reached by 55degree C under vertical irradiance of lower 500$W/m^2$. And the temperature difference between these modules was about 15degree C. To analyze the output performance of module according to temperature variation, separate module was manufactured and measured by sun-simulator. The results showed that 1 degree temperature rise reduced about 0.45% of output power.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.18 no.6
• /
• pp.183-190
• /
• 2004

This paper proposes a methodology to solve problems upon the circuit design applied to inductor load by applying a circuit to improve power factor with is partial switching PFC module to the power supply system for cooling/heating inverter air conditioner and by designing an input power section in compliance with IEC555-2 on the basis of better input power factor and minimized harmonic components of current. On the other hand, this paper suggested how to control the increase of output voltage along with tぉw current waves and partial switching PFC circuit as well, which can provide the output as twice as input voltage This study applied a method to control the compressors of air conditioner by means of increased the voltage applicable to compressor motor by lowering switching number conclusively, it could solve questions about efficiency, economics, electronic noise and so forth. and so that the reasonable voltage for running moor could be set up along with lower power consumption of air conditioner than estimated It was demonstrated that total sum of energy efficiency to operate system was increased to the extent of valid level. And all this merits and appropriateness was proved by computer simulation and experience.

• Fire Science and Engineering
• /
• v.26 no.4
• /
• pp.82-88
• /
• 2012

To analyze the thermal characteristics of wire connection part that is connected to a screw-clamping terminal block depending on screw torque, the normal screw torque defined in KS C 2625 and the abnormal screw torque that can occur due to loosened screws resulting from defective work or aged deterioration were used as experimental variables. After the same load was applied to normal and abnormal screw torques, the thermal characteristics of the wire connector were measured and compared with a thermal imaging camera. The findings from this study will be used to detect heating due to defective screw torque at terminal block connections during electric safety inspection in the future and minimize the hazard of electric fire.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.4
• /
• pp.464-469
• /
• 2019

Tapered roller bearings are used widely in vans, trucks, and trains because they can support the vehicle in a stable manner even under a heavy load. The cage of a tapered roller bearing maintains the gap between the rollers, which prevents friction wear and suppresses heating. If the cage is severely deformed due to resonance, the roller may not be able to roll smoothly and even leave the cage. Consequently, it is very important to analyze the dynamic characteristics of the cage for reliable performance of a bearing. The cage essentially has geometrical tolerance in the manufacturing process. In this paper, the effects of those geometrical imperfections on the dynamic characteristics of the cage were investigated. As a result, natural frequency separation occurred near the natural frequency of the ideal cage due to geometrical imperfections. In addition, the interval was proportional to the magnitude of the geometric error, and the interval increased with increasing mode number.