• KIEAE Journal
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• 제16권6호
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• pp.13-19
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• 2016

Purpose: In this study, we examined outdoor air fraction using historical data of actual Air Handling Unit (AHU) in the existing building during intermediate season and analyzed optimal outdoor air fraction by control types for economizer. Method: Control types for economizer which was used in analysis are No Economizer(NE), Differential Dry-bulb Temperature(DT), Diffrential Enthalpy(DE), Differential Dry-bulb Temperature+Differential Enthalpy(DTDE), and Differential Enthalpy+Differential Dry-bulb Temperature (DEDT). In addition, the system heating and cooling load were analyzed by calculating the outdoor air fraction through existing AHU operating method and control types for economizer. Result: Optimized outdoor air fraction through control types was the lowest in March and distribution over 50% was shown in May. In case of DE control type, outdoor air fraction was the highest of other control types and the value was average 63% in May. System heating load was shown the lowest value in NE, however, system cooling load was shown 1.7 times higher than DT control type and 5 times higher than DE control type. For system heating load, DT and DTDE is similar during intermediate season. However, system cooling load was shown 3 times higher than DE and DEDT. Accordingly, it was found as the method to save cooling energy most efficiently with DE control considering enthalpy of outdoor air and return air in intermediate season.

• 한국화재소방학회논문지
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• 제24권4호
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• pp.27-32
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• 2010

최근 도시 중심의 산업화에 의한 도시 내 인구 밀도의 증가는 생활환경의 고밀화, 집적화를 초래하였다. 이에 따라 도시 내에는 다수의 인원을 수용할 수 있는 다수의 고층 건축물이 축조되고 있는 추세이다. 하지만 고층 건물은 건물의 구조적 특성에 의해 화재발생 시 수직적 통로를 통한 연기확산속도가 증가하게 되어 높은 인명피해를 야기하게 된다. 그러므로 본 연구에서는 고층건물의 제연해석을 위해 개발된 ASCOS 프로그램을 기반으로 엔탈피 보존방정식을 추가하여 에너지 전달을 고려한 제연해석 프로그램(CAU_ESCAP)을 개발하였다. CAU_ESCAP는 ASCOS의 제연해석결과와 비교를 통해 프로그램의 타당성을 검증을 하였으며, 건물 내 화재 발생에 대해 적용하여 건물 내 제연 특성을 분석하였다.

• 설비공학논문집
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• 제9권4호
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• pp.545-551
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• 1997

As the cooling energy requirement in an office building increases due to the increased internal heat gains, the effort to minimize the energy consumption through efficient operation of existing HVAC systems will be beneficial. In this study, one of the energy conserving efforts in an office building, operational strategies of Economizer Cycle Control have been investigated through DOE-2.1E computer simulation. The findings can be summarized : 1) Economizer Cycle Control saves energy throughout the year, 2) Econo-Limit-T must be applied seasonally based on the outside and return air conditions, 3) use of Enthalpy control is more energy efficient than that of Temperature control.

• 한국안전학회지
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• 제26권4호
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• pp.102-110
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• 2011

For decreasing of the casualties and designing of the smoke control systems in the ultra high-rise building, the programs for analysis of smoke control were developed for prediction of smoke spread and distributions of pressure and temperature in building fire situation. In this study, coupling algorithm between mass and enthalpy conservations was modified for improving the applicability of the CAU_ESCAP which program can consider the energy transfer. The fire situation in ultra high-rise building was applied by using the modified CAU_ESCAP. Results of pressure difference predicted by modified CAU_ESCAP are higher than results of ASCOS as stack effect is generated due to the increasing of stairway temperature. Moreover, theoretically, the result of the neutral plane is more accurate than the result of ASCOS, in fire situation of ultra high-rise building.

• 한국대기환경학회지
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• 제12권4호
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• pp.479-485
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• 1996

Volatile organic compounds are air pollutants exhausting from industrial process, evaporation of solvent, and so on. Most of VOCs are the combustible gas of low calorific value as it is diluted by air. The systems burning such a hazardous gas need to increase enthalpy in order to increase flame stability. In this study an incinerator with reciprocating flow in the honeycomb ceramic has been used for the experiment of VOCs control. By the reciprocating flow system, the enthalpy of combustion gas is effectively regenerated into the enthalpy increases of the combustible gas through the honeycomb ceramic, which provides a heat storage. The position of the reaction zone is strongly dependent on the parameters of mixture velocity and time frequency. Flame front is changed to the point where burning velocity is coincided with burning velocity in the honeycomb ceramic. In this system it is important that flame front should be located symmetrically at the center of honeycomb ceramic for the purpose of increasing the reaction rate at one point. Peak temperature becomes higher with decreasing time frequency, at which the flow direction is regularly reversed.

• 한국식품영양과학회지
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• 제32권8호
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• pp.1262-1269
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• 2003

효소류의 떡 노화에 미치는 영향을 검토하였다. DSC 열특성의 검토에서 호화개시온도는 GP(glucoamylase+pullulanase)로 처리한 경우가 71.1$^{\circ}C$로 가장 낮고 그 다음이 $\beta$-amylase, $\alpha$-amylase 순이었다. 또 호화최대온도는 효소 처리한 것이 대조구에 비해서 대부분 낮은 편이었으며 그 중 GP처리한 것이 가장 낮은 것으로 나타났다. 또 떡의 용융 enthalpy는 GP, $\beta$-amylase, $\alpha$-amylase 순으로 증가하였으며 GP의 용융 enthalpy값이 다른 경우보다 많이 낮게 나타났다. 재결정도는 GP의 값이 크게 낮은 것으로 나타났다. Avrami exponent(n)는 0.90 ∼ 1.20 범위에 있었으며 노화속도의 시간상수 1/k은 GP, $\beta$-amylase, $\alpha$-amylase, Control의 순이었다. 효소류를 첨가한 떡의 조직감은 대조구에 비해서 차이를 보였으며 종류별 효과는 GP, $\beta$-, $\alpha$-amylase의 순으로 나타났다. L＊ 값은 $\beta$-amylase를 제외하고는 모두 감소하고 a＊ 값은 효소간 5% 수준에서 유의차를 나타내었다. b＊ 값의 경우는 GP는 청색 방향으로, $\beta$-, $\alpha$-amylase는 반대인 황색 방향으로 변하였다. 효소 처리한 떡의 관능검사는 효소 처리한 것이 대조구보다 다소 높은 값을 나타내어 좋은 관능성을 보여주었다.

• 한국지열·수열에너지학회논문집
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• 제7권1호
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• pp.51-58
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• 2011

Due to enhanced sealing and insulation of buildings, extensive use of glasses for building envelopes and increased use of heat generating office equipments, energy consumption of modem buildings for cooling is steadily increasing. With outdoor air cooling(ODAC) system, cooling load can be reduced by exchanging indoor air with the cold outdoor air during spring and fall seasons. If ODAC is operated based only on temperature, total cooling load may virtually increase if the outdoor humidity is high. To overcome this problem, ODAC should be controlled based on enthalpy. In this work energy saving characteristics of enthalpy controlled ODAC is studied using dynamic simulation. The result shows that cooling load can be reduced by 27% by adopting ODAC.

• 국제초고층학회논문집
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• 제6권1호
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• pp.101-111
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• 2017

The objective of this study is to determine the effectiveness of a modified air-side economizer in improving indoor air quality (IAQ). An air-side economizer, which uses all outdoor air for cooling, affects the building's IAQ depending on the outside air quality and can significantly affect the occupants' health, leading to respiratory and heart disease. The Air Quality Index (AQI), developed by the US Environmental Protection Agency (US EPA), measures air contaminants that adversely affect human beings: PM10, PM2.5, SO2, NO2, O3, and CO. In this study, AQI is applied as a control for the operation of an air-side economizer. The simulation is analyzed, comparing the results between the differential enthalpy economizer and AQI-modified economizer. The results confirm that an AQI-modified economizer has a positive effect on IAQ. Compared to the operating differential enthalpy economizer, energy increase in an operating AQI-modified economizer is 0.65% in Shanghai and 0.8% in Seoul.

• Elastomers and Composites
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• 제19권1호
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• pp.13-31
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• 1984

The purposes of this dissertation are to demonstrate that DSC theromoanaytical methods of vulcanization can provide useful informations on the vulcanization characteristics of industrial formulations and also provides the potential basis for a rapid and complete method of sulfur and vulcanizing accelerator analysis for quality control. The influences of those factors such as heating rate, scan temperature, vucanizing accelerator's type and concentration upon vulcanization exotherm in NR and NBR compounds in the presence of vulcanizing accelerators such as TMTD,MBTS,DPG,TMTM,CBS, and MBT were evaluated by means of DSC. In order to examine the credibility in the DSC method, the same samples which were used for DSC method were studied to compare the DSC results with the ODR (Oscillating Disk Rheometer) data. The results obtained were as follows 1. In the DSC dynamic experiments, the observed enthalpy results from vulcanization depends upon the heating rate; In the range of 2 to $20^{\circ}C/min$ of heating rate, as the heating rate was increased the enthalpy change was also increased. However, over the heating rate of $30^{\circ}C/min$ it was observed that the enthalpy change was decreased as the heating rate was further increased. Without regard to the change of enthalpy, tremendous instantaneous heat evolving was observed in the range of high heating rates. 2. For the samples which are added with various vulcanizing accelerators, the activation energies of vulcanization were as follows; 3. Regarding to the influences of vulcanizining accelerator's types upon the characteristics of vulcanization exotherm, NR and NBR compounds in the presence of thiuramsulphide compounds type accelerators such as TMTD, TMTM, were exhibited sharper and higher vulclanization exotherm than others. From the resuts of DSC thermograms which was distributed in even shape in the broad temperature range, it was clearly shown that the guanidine compounds type accelerator such as DPG acts as a delayed acting accelerator. 4. In the comparison of DSC and ODR results, the dependency of temperature in the cure rate and the observed conversions show good agreements between two results. 5. In the same curatives, by the comparison of glass transition temperatures, it was possible to predict relative values of maximum torques. Consequently, from the present studies, it is shown that the DSC thermoanalytical method can provide an alternate new method for rapid and complete quality control analysis of rubber industry.

• 한국표면공학회지
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• 제44권6호
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• pp.250-254
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• 2011

NiO-AZO films were deposited on glass substrate by DC and RF magnetron co-sputtering system in pure $O_2$ gas without substrate heating during deposition. In order to control the chemical composition of the film, NiO target was supplied with constant RF power of 150 W and AZO target (doped with 2.98 at% aluminum) with DC power varied between 40 W to 80 W. Deposited NiO-AZO films were evaluated by structural and chemical analysis. With introducing AZO, XRD and XPS data reveal that NiO were supplied with more oxygen. these results could be strongly affected by the higher bond enthalpy of NiO compared to ZnO, which makes it possible for NiO to obtain excessive oxygen from ZnO.