• 한국태양에너지학회 논문집
• /
• 제31권3호
• /
• pp.109-115
• /
• 2011

It can gain both the electric energy production and disperse of light at the same time if DSSC is applied in the building as window system. It means to help facade design and to be used in lighting, heating, cooling energy directly by applicating DSSC BIPV window that is possible to daylighting and materialization of color. For this, optical characteristics analysis that is basic step must take precedence. So, basic databases of DSSC are builded and optical performances according to the double and triple glazing are evaluated by analyzing spectral data of various colored DSSC. As a result, Green(4) has the highest visible transmittance that is 28.8%, and Blue(3) has the lowest that is 0.3%. And, in case of optical performance of Green(4) depending on the incidence angle, SHGC and Tsol are decreased sharply from more than $60^{\circ}C$. Finally, It is judged that Red(4), Green(1), (4), Blue(4) are suitable for application in office building because visible transmittance is high and solar heat gain coefficient is low relatively in spite of composing to double and triple glazing.

• 대한기계학회논문집B
• /
• 제26권11호
• /
• pp.1622-1629
• /
• 2002

To enhance isothermal characteristics of glass-farming surface, a rectangular parallelepiped heat pipes was fabricated, tested, and analyzed. The working fluid was sodium and the wall material was stainless steel 304. The dimension of the heat pipe was 210 (L) $\times$ 140(W) $\times$ 92(H)mm. A lattice structure covered with screen mesh was inserted to promote return of working fluid. The bottom side of heat pipe was heated electrically and the top side was cooled by liquid circulation. The temperature distribution at the bottom surface was of major concern and was monitored to determine isothermal characteristics. A frozen start-up of rectangular parallelepiped liquid metal heat pipe was tested. The operating mode of the sodium heat pipe was affected by the temperature of cooling zone, input heat flux, and the operating temperature of heat pipe. The heat pipe operated in a normal fashion as long as the heat flux was over 5.78W/cm$^2$, and the inside wall temperature of condenser part was above 95$^{\circ}C$ The maximum temperature difference at the bottom surface was observed to be 32$^{\circ}C$ when the operating temperature of the heat pipe was operating normally around 50$0^{\circ}C$. The result showed that a sodium heat pipe was very effective in reducing significantly the temperature difference in the glass-forming surface.

• 대한기계학회논문집A
• /
• 제35권4호
• /
• pp.383-391
• /
• 2011

최근 차체 경량화를 위한 여러 가지 방법 가운데 고온에서 가공하여 성형성을 확보하고, 이후 열처리를 통하여 고강도를 가질 수 있는 프레스 열간 성형 및 핫스탬핑 기술이 각광을 받고 있으며, 이에 따라 핫스탬핑용 재료인 보론 첨가 강판의 수요도 늘어나고 있는 추세이다. 본 연구에서는 핫스탬핑용보론 첨가 강판의 우수한 경화능을 보이는 임계 최적 열처리 조건을 파악하고자, Al+Si 코팅이 된 보론강판을 각기 다른 온도로 열처리하여 수냉 조건에 따른 기계적 특성 및 조직을 관찰하였다. 또한, 이 결과를 토대로 선별된 기계적 특성이 우수한 보론강 시험편과 일반 냉연 강판인 SPRC 340과 SPRC 590 2종류의 상대재를 활용하여 특정 점용접 조건에서 용접을 실시하고, 보론강 및 상대재의 기계적 특성 변화에 따른 용접 후의 기계적 특성 및 조직, 그리고 코팅층 유무에 따른 특성 변화를 연구하였다.

• 한국건축친환경설비학회 논문집
• /
• 제12권6호
• /
• pp.669-679
• /
• 2018

Energy consumption savings in buildings should be reviewed in diverse areas such as air conditioning system and lighting responsible for cooling and heating, and energy management systems such as BAS (Building Automation System) and BEMS (Building Energy Management System) are introduced to improve energy consumption efficiency and to promote economic control of related facilities by integrated management of energy generated and consumption in buildings. The measured building of this study uses regenerative geothermal system. Measured values of heat pump and system COP were 4.7 and 4.2 respectively, and they were found to be higher 11.9% and 23.5% than rated values. As a result of analyzing the air conditioning and lighting energy from the first floor to the fourth floor performing the air conditioning, the second and third floors, which have a high frequency of use, are compared with the first and fourth floors 50% higher energy consumption ratio. On the other hand, the general heat storage system uses the nighttime power of the previous day to store heat and use it the next day. The total number of days of abnormal operation during the summer season is 61 days. The electricity cost corresponding to the abnormal operation is 1,840,641 KRW, and the normal operation using the nighttime power is 1,363,561 KRW, which is difference of 477,080 KRW, 35% increase in cost. We will utilize it as the main data of BEMS through analysis of winter operation characteristics as well as summer operation characteristics.

• 한국수산과학회지
• /
• 제51권6호
• /
• pp.632-639
• /
• 2018

To develop the high-value added seafood products from a regional speciality seafood, the seasoned dried pen shell Atrina pectinata adductor (SDPA) and seasoned smoke-dried pen shell adductor (SSPA) samples were prepared, and their optimal processing conditions, quality metrics, and shelf-life characteristics were examined. SDPA and SSPA samples were produced by thawing of frozen pen shell adductor, and cutting it into 6-7 mm slices, hot-air drying ($60^{\circ}C$, 20 min) or smoking ($110^{\circ}C$, 20 min), seasoning ($4^{\circ}C$, 12 h) with seasoning powder (60% sorbitol, 15% sucrose, 16% salt and 9.0% monosodium glutamate), hot-air drying ($60^{\circ}C$, 3 h), torching, vacuum-packaging in a laminated plastic film bag, heat treating with hot-water ($85^{\circ}C$, 15 min), and cooling. The moisture content of SDPA and SSPA samples was 44.5 and 43.0%, respectively, and the water activity was 0.845 and 0.842. The total amino acids in SDPA and SSPA samples were 20,986.8 and 21,312.4 mg/100 g, respectively, and the major amino acids in both products were aspartic acid, serine, glutamic acid, proline, glycine, alanine, valine, leucine, phenylalanine, lysine and arginine. The primary minerals were Na, S, K and P. Incubating tests indicated that the quality of SDPA and SSPA samples was maintained for 30 days of storage.

• 한국전기전자재료학회논문지
• /
• 제36권4호
• /
• pp.408-412
• /
• 2023

In this paper, in order to analyze high electrical insulation and cooling performance using mineral oil, the liquid insulating oil was changed in electrode shape and distance between electrodes to compare and analyze electrical characteristics according to equal electric field, quasi-equivalent electric field, and unequal electric field. As a result, the breakdown voltages were 36,875 V and 36,875 V in the form of sphere-sphere and plate-plate electrodes with equal electric fields. The breakdown voltage was 31,475 V in the sphere-plate electrode type, which is a quasi-equilibrium field, and the breakdown voltage was 28,592 V, 27,050 V, and 22,750 V in the needle-needle, sphere-needle, and needle-plate electrode types, which are unequal fields. Through this, it is possible to know the difference in breakdown voltage according to the type of electric field. The more equal the field, the higher the breakdown voltage, and the more unequal field, the lower the breakdown voltage. The difference in insulation breakdown voltage could be seen depending on the type of electric field, the insulation breakdown voltage was higher for the more equal electric field, and the insulation breakdown voltage was lower for the more unequal electric field. Also, it was confirmed that the closer the distance between the electrodes, the higher the insulation breakdown voltage, the higher the insulation breakdown current, and the insulation breakdown voltage and the insulation breakdown current were proportional.

• Tribology and Lubricants
• /
• 제23권6호
• /
• pp.288-297
• /
• 2007

Adhesion and friction tests were carried out in order to investigate the effect of temperature on the tribological characteristics of poly (methylmethacrylate) (PMMA) film using AFM. The pull-off and friction forces on the PMMA film were measured under a high vacuum condition (below $1{\times}10^{-4}$ Pa) as the temperature of the PMMA film was increased from 300 K to 420 K (heating) and decreased to 300K (cooling). Friction tests were also conducted in both high vacuum and air conditions at room temperature. When the temperature was 420 K, which is 25 K higher than the glass transition temperature $(T_g)$ of PMMA, the PMMA film surface became deformable. Subsequently, the pull-off force was proportional to the maximum applied load during the pull-off force measurement. In contrast, when the temperature was under 395 K, the pull-off force showed no correlation to the maximum applied load. The friction force began to increase when the temperature rose above 370 K, which is 25 K lower than the $T_g$ of PMMA, and rapidly increased at 420 K. Decrease of the PMMA film stiffness and plastic deformation of the PMMA film were observed at 420 K in force-displacement curves. After the heating to 420 K, the fiction coefficient was measured under the air condition at room temperature and was found to be lower than that measured before the heating. Additionally, the RMS roughness increased as a result of the heating.

• Journal of Advanced Marine Engineering and Technology
• /
• 제30권4호
• /
• pp.463-473
• /
• 2006

The effect of tube diameter on heat and mass transfer characteristics of absorber in absorption chiller/heater using LiBr solution as a working fluid has been investigated by both of numerical and experimental study to develop a high performance and compact absorber. The diameter of the heat exchanger tube inside absorber was changed from 15.88mm to 12.70mm and 9.52mm. In numerical study a model of vapor pressure drop inside tube absorber based on a commercial 20RT absorption chiller/heater was performed. The effect of tube diameter, longitudinal pitch, vapor Reynolds number, longitudinal pitch to diameter ratio on vapor pressure drop across the heat exchanger tube banks inside absorber have been investigated and found that vapor pressure drop decreases as tube diameter increases, longitudinal pitch increases, vapor Reynolds number decreases and longitudinal pitch to diameter ratio increases. In experimental study, a system includes a tube absorber, a generator, solution distribution system and cooling water system was set up. The experimental results shown that the overall heat transfer coefficient, mass transfer coefficient. Nusselt number and Sherwood number increase as solution flow rate increases. In both of study cases, the heat and mass transfer performance increases as tube diameter decreases. Among three different tube diameters the smallest tube diameter 9.52mm has highest heat and mass transfer performance.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2005년도 춘계학술대회
• /
• pp.339-344
• /
• 2005

A PEMFC system model for FCEV was constructed and simulated numerically to examine the heat/water flow of the system and air/fuel humidification process for various operation conditions (ambient pressure /temperature/humidity, operating temperature, power load). We modeled PEMFC stack which can generate maximum electricity of about 80 kW. This stack consists of 400 unit cells and each unit cell has $250cm^2$ reacting area. Uniform current density and uniform operating voltage per each cell was assumed. The results show the flow characteristics of heat and water at each component of PEMFC system in macro-scale. The capacity shortage of the radiator occurred when the ambient was hot $(over\;40^{\circ}C)$ and power level was high (over 50 kW). In spite of some heat release by evaporation of water in stack, heat unbalance reached to 20kW approximately in such a severe operating condition. This heat unbalance could be recovered by auxiliary radiators or high speed cooling fan with additional cost. In cold environment, the capacity of radiator exceeded the net heat generation to be released, which may cause a problem to drop the operating temperature of stack. We dealt with this problem by regulating mass flow rate of coolant and radiator fan speed. Finally, water balance was not easily broken when we retrieved condensed and/or unused water.

• Ocean and Polar Research
• /
• 제23권4호
• /
• pp.361-376
• /
• 2001

The characteristics of SST variability in the East Sea are analyzed using NOAA/AVHRR weekly SST data with about $0.18^{\circ}{\times}0.18^{\circ}$ resolution ($1981{\sim}2000$) and reconstructed historical monthly SST data with $2^{\circ}{\times}2^{\circ}$ resolution $(1950{\sim}1998)$. The distinct feature of wintertime SST is high variability in the western and eastern parts of $38^{\circ}{\sim}40^{\circ}$ latitudinal band, which are the northern boundary of warm current in the East Sea during winter. However, summertime SST exhibits variability with similar magnitude in the entire region of the East Sea. The analysis of remote correlation also shows that SST in the East Sea is closely correlated with that in the region of Kuroshio in winter, but in summer is related with that in the western and eastern regions of the same latitudes. From these results it is postulated that the SST variability in the East Sea may be related with the variations of East Korean Warm Current and Tsushima Warm Current in winter, but in summer probably with the variations of atmospheric components. In the analysis of ENSO related SST anomaly, a significant negative correlation between SST anomalies in the East Sea and SST anomalies in the tropical Pacific is found in the months of August-October (ASO). The SST in the ASO period shows more significant cooling in E1 $Ni\~{n}o$ events than warming in La $Ni\~{n}a$ events. Also, the regional analysis shows by the Student's t-test that the negative SST anomalies in the E1 $Ni\~{n}o$ events are more significant in the southwestern part of the East Sea.