• Advances in Energy Research
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• 제5권1호
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• pp.65-77
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• 2017

The latest UK Climate Projections (UKCP09) show that mean daily temperatures will increase everywhere in the United Kingdom. This will significantly affect the thermal and energy performance of the current building stock. This study examines an institutional fully glazed building and looks into the changes in the cooling loads and thermal comfort of the occupants during the occupied hours of the non-heating period. Furthermore, it investigates the effect of relative humidity (RH) on thermal comfort. The Design Summer Year (DSY) 2003 for London Heathrow has been used as a baseline for this study and the DSY 2050s High Emissions scenario was used to examine the performance of the building under future weather conditions. Results show a 21% increase of the cooling loads between the two examined scenarios. Thermal comfort appears to be slightly improved during the months of May and September and marginally worsen during the summer months. Results of the simulation show that a relative humidity control at 40% can improve the thermal comfort for 53% of the occupied hours. A comparison of the thermal comfort performance during the hottest week of the year, shows that when the relative humidity control is applied thermal comfort performance of the 2050s is similar or better compared to the thermal comfort performance under the baseline.

• Environmental Engineering Research
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• 제16권2호
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• pp.103-109
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• 2011

This work experimentally determined the effect of thermal and microwave pretreatments on the anaerobic digestion of mixtures of municipal primary and secondary sludges in semi-continuous mesophilic digesters at hydraulic retention times (HRT) of 20, 15, 10, 7, and 5 days. The ratio of soluble chemical oxygen demand (COD) to total COD in thermally pretreated and microwaved sludges at $80^{\circ}C$ was 2.7 and 3.2 times higher than that of raw sludge, respectively. The volatile solids (VS) and COD removal efficiencies in all three digesters fed with raw (control), thermally pretreated (TM), and microwaved (MW) sludges decreased as the HRT was reduced. The highest relative improvement in VS removal compared to the control occurred at the HRT of 5 days in the TM and MW (29 and 41% higher than the control, respectively). At this HRT, improvement in the COD removal efficiencies in the TM and MW compared to the control was 28 and 53%, respectively. Improvements in biogas production compared with the control increased in both the TM and MW as the HRT was reduced to 5 days. The relative improvement in daily biogas production compared to the control from the TM and MW was 33 and 53% higher than the control at the HRT of 5 days, respectively. The results show that microwave pretreatment is more effective than thermal pretreatment in increasing the solubilization degree and mesophilic anaerobic biodegradability of sewage sludge.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 B
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• pp.919-921
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• 1995

In this paper, development of Thermal Printer Head(TPH) controller by using gate array having high reliability and good performance is proposed. Over the 3000 gates are performed to control print image data signals and relative peripheral hardwares. The proposed gate array has TPH control circuit, print control and step motor drive, and print image data control, decoder output control parts. This TPH controller will be a good application to FAX or label printer and barcode printers.

• 토지주택연구
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• 제1권1호
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• pp.19-25
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• 2010

최근 에너지 절약을 화두로 건물에서의 에너지 절약기술들이 크게 요구되어 지는 반면 재실자의 온열쾌적환경은 비교적 비중 있게 다루어지지 않고 있다. 실내공간의 쾌적성은 재실자의 만족감과 더불어 생산성을 향상시키는 등의 역할을 하며, 최근 삶의 질 향상 등에 따라 그 필요성이 크게 요구되고 있는 실정이다. 따라서 본 연구에서는 공동주택을 대상으로 겨울철 난방 시 쾌적지표를 통한 실내 온열환경 제어의 타당성을 검토하고자 시뮬레이션을 수행하였으며, 주거건물에서의 일상적인 실내온도와 에너지 절약 설계기준에서 제시한 실내 설정온도, 그리고 쾌적지표를 설정으로 한 각 제어조건의 온열환경과 에너지 소비량을 비교 분석 및 검토하였다. 본 연구결과에 따르면, 쾌적지표인 PMV로 실내환경을 제어했을 때 에너지 절약설계 기준인 $22^{\circ}C$로 실내온도를 설정하였을 때보다 에너지 소비량은 29% 증가하지만 주거용 건물에서 일반적으로 유지되는 실내온도인 $24^{\circ}C$ 보다는 에너지소비량은 11% 정도 감소하며, 온열쾌적감도 각 제어조건 중 가장 우수하게 나타났다. 따라서 여러 가지 제어변수들을 통한 연구가 지속된다면 주거용 건물에서도 쾌적지표를 활용한 실내 공간의 제어방법은 건물의 에너지를 절약하고 실내 환경의 쾌적성을 증대시키는 주요기술이 될 수 있을 것으로 기대된다.

• 한국주거학회논문집
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• 제14권1호
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• pp.19-27
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• 2003

This study aims to survey the living spaces of the welfare facilities for the aged to get the objective relationships between the physical thermal environment and the users' subjective responses. The surveys were made twice in winter and once in summer during 2001 and 2002. An ambient temperature, relative humidity, air velocity, globe temperature were measured as physical elements of thermal environment and the ASHRAE Psychophysical Voting Scale were used as an evaluation index for subjective responses. As the results, the aged respond thermally comfortable, in spite of the differences among important factors such as thermal sensations, humidity sensations and air velocity sensations. Also the physical thermal environmental elements and the subjective responses indices exceed thermal comfort range calculated by PMV(Predicted Mean Vote) and PPD(Predicted Percentage Dissatisfied). It shows that the insulation of walls of the facilities is not enough for heating and cooling seasons, and the indoor environmental control is necessary.

• 한국주조공학회지
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• 제25권6호
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• pp.254-258
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• 2005

Semisolid process is possible in any material system possessing a freezing range where the microstructure should consist of the nondendritic globular solid phase separated and enclosed by the liquid phase, referred to as semisolid slurry. There are two primary semisolid processing routes, thixocasting and rheocasting. Especially, rheocasting process has become a new focus in the field of semisolid process because of its many advantages such as no special billet required and possibility of in-house scrap recycling, compared with the thixocasting process. In-Ladle direct thermal control (DTC) rheocasting has been developed, based on the fact that there is slurry and mush transition in every molten metal and the transition, which normally occurs in the range of liquid traction of 0.1 to 0.6, could be controlled by controlling solid shape and relative solid-liquid interfacial energy. In this study, A356 Al alloy was investigated to verify In-Ladle DTC rheocasting for obtaining semisolid slurry. Modeling of heat transfer was carried out to investigate the effect of pouring temperature and ladle material, geometry and temperature and the simulation results were compared with the actual experiments.

• 한국세라믹학회지
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• 제31권3호
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• pp.321-329
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• 1994

Functionally gradient materials(FGM), which have the continuous or stepwise variation in a composition and microstructure, are being noticed as the material that solves problems caused by heterogeneous interface of coating or joining. And these materials also expect new functions occured by gradient composition itself. Therefore, to examine possibility of thermal barrier materials, TZP/Mo·FGM and TZP/Ni·FGM were fabricated by sintering method. As to the sintered specimens, sintering shrinkage, relative density and Vicker's hardness in each composition were examined. The phenomena due to the difference of sintering shrinkage velocity during sintering process and the thermal stress induced through differences of thermal expansion coefficient in FGM were discussed. And the structure changes at interface and microsturcture of FGM were investigated. As a results, the difference of shrinkage between ceramic and metal was about 14% in TZP/Mo and 7% in TZP/Ni. The relative density and hardness were considerably influenced by metal content changes. Owing to unbalance of sintering shrinkage velocity between ceramic and metal, various sintering defects were occured. To control these sintering defects and thermal stress, gradient composition of FGM should be narrow. The microstructure changes of FGM depended on the ceramic or metal volume percents and were analogous to the theoretical design.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 춘계학술발표대회
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• pp.15-15
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• 2011

As you know, boron compounds, borax ($Na_2B_4O_5(OH)_4{\cdot}8H_2O$) etc. were known thousands of years ago. As for natural boron, it has two naturally occurring and stable isotopes, boron 11 ($^{11}B$) and boron 10 ($^{10}B$). The neutron absorption $^{10}B$ is included about 19~20% with 80~81% $^{11}B$. Boron is similar to carbon in its capability to form stable covalently bonded molecular networks. The mass difference results in a wide range of ${\beta}$ values between the $^{11}B$ and $^{10}B$. The $^{10}B$ isotope, stable with 5 neutrons is excellent at capturing thermal neutrons. For example, it is possible to decrease a thermal neutron required for the nuclear reaction of uranium 235 ($^{235}U$). If $^{10}B$ absorbs a neutron ($^1n$), it will change to $^7Li+^1{\alpha}$ (${\alpha}$ ray, like $^4He$) with prompt ${\gamma}$ ray from $^{11}B$ $^{11}B$ (equation 1). $$^{10}B+^1n\;{\rightarrow}\;^{11}B\;{\rightarrow}\; prompt \;{\gamma}\;ray (478 keV), \;^7Li+4{\alpha}\;(4He)\;\;\;\;{\cdots}\; (1)$$ If about 1% boron is added to stainless steel, it is known that a neutron shielding effect will be 3 times the boron free steel. Enriched boron or $^{10}B$ is used in both radiation shielding and in boron neutron capture therapy. Then, $^{10}B$ is used for reactivity control and in emergency shutdown systems in nuclear reactors. Furthermore, boron carbide, $B_4C$, is used as the charge of a nuclear fission reaction control rod material and neutron cover material for nuclear reactors. The $B_4C$ powder of natural B composition is used as a charge of a control material of a boiling water reactor (BWR) which occupies commercial power reactors in nuclear power generation. The $B_4C$ sintered body which adjusted $^{10}B$ concentration is used as a charge of a control material of the fast breeder reactor (FBR) currently developed aiming at establishment of a nuclear fuel cycle. In this study for new boron compound, silicon boride ceramics for capturing thermal neutrons, preparation and characterization of both silicon tetraboride ($SiB_4$) and silicon hexaboride ($SiB_6$) and ceramics produced by sintering were investigated in order to determine the suitability of this material for nuclear power generation. The relative density increased with increasing sintering temperature. With a sintering temperature of 1,923 K, a sintered body having a relative density of more than 99% was obtained. The Vickers hardness increased with increasing sintering temperature. The best result was a Vickers hardness of 28 GPa for the $SiB_6$ sintered at 1,923K for 1 h. The high temperature Vickers hardness of the $SiB_6$ sintered body changed from 28 to 12 GPa in the temperature range of room temperature to 1,273 K. The thermal conductivity of the SiB6 sintered body changed from 9.1 to 2.4 W/mK in the range of room temperature to 1,273 K.

• 전기전자학회논문지
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• 제19권4호
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• pp.603-609
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• 2015

열 쾌적 제어는 실내 환경의 질을 나타내는 기본 요소로써 건물에서 사용되는 에너지와 거주자의 만족도에 매우 밀접하게 연관되어 있다. 본 논문에서는 실내의 쾌적 상태(Predictive Mean Vote)를 검출하고, 목표 소비 전력 내에서 냉난방 온도, 습도, 풍량을 제어함으로써 에너지를 절감하고 근무자에게 쾌적한 환경을 제공할 수 있는 스마트 쾌적 제어 알고리즘을 제안하였다. 시뮬레이션 결과, 열 쾌적 제어에 의한 냉난방제어는 기존의 일반 냉난방기에 비해서 실내의 쾌적도는 그대로 유지한 상태에서 0.5kW의 전력을 절감할 수 있고, 조명제어 알고리즘이 적용된 조명 제어에 의해서 49.2%의 조명 개선 효과가 이루어짐을 알 수 있었다. 시뮬레이션을 통해서 검증된 쾌적 제어 알고리즘을 기존의 냉난방기에 적용할 경우 쾌적도는 유지하고 에너지는 절감할 수 있을 것으로 예상된다.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제5B권4호
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• pp.392-398
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• 2005

This paper presents technologies that have strategic importance in future motor drives. The underlying strategic issue for motor drives is maintaining cost while increasing certain dimensions of functionality. The dimensions of functionality which should increase include reliability and added value features such as providing continuous energy optimization, providing sensing of the driven system suitable for application specific diagnostic purposes, and providing continuously optimal thermal utilization of the capability of the drive. This paper will address each of these issues and discuss the technology status for each case, with a focus on research needed to fully deliver the needed functionality.