• 설비공학논문집
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• 제16권6호
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• pp.499-505
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• 2004

The objective of this study is to investigate the effect of supercooling repression on the TMA clathrate by adding ethylene glycol. For this purpose, phase change temperature, supercooling, specific heat, latent heat and rate of volume change were measured and evaluated experimentally for heat source temperatures of -6$^{\circ}C$, -7$^{\circ}C$, -8$^{\circ}C$. The results show that supercooling was decreased. Thus the experimental results are expected to be used for the increase of coefficient of performance of low temperature thermal storage system in the building.

• 토지주택연구
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• 제14권3호
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• pp.137-144
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• 2023

토공계획은 자연상태의 원지반 토량을 절취하여 흐트러진 상태의 토량을 운반하고 성토지반의 활용도에 따라 다짐을 하는 과정에서 토질의 체적변화를 고려하여 수립하여야 한다. 흙의 상태에 따른 체적의 변화를 구하기 위해 일반적으로 심도 2m 깊이에서 시험굴 조사를 통해 얻어진 토량환산계수를 사용하게 되며, 굴착 깊이에 따른 토질의 성질을 고려하지 않고 전체 토공량에 일률적으로 적용하다 보니 토공량 산정에 오차가 발생하고 있다. 특히 신도시 택지개발과 같이 대량의 토공량이 필요한 조성공사의 경우 작은 오차에도 토공량의 차이는 크게 발생하게 된다. 본 연구에서는 심도 2m이상 토질의 물리적 특성을 조사하고 기존의 설계기준인 심도 2m의 토량환산계수와 비교 검토한 결과 굴착 심도가 깊고 대규모 토공사의 경우 심도별 토량환산계수(C)를 적용할 경우 절토량을 줄일 수 있는 것으로 나타났다.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.1155-1160
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• 2008

In the present study investigated the heat dissipation characteristics of the natural convection type radiator by using the latent heat from a solid-liquid PCM(Phase Change Material). Total radiator volume size is $423{\times}295{\times}83\;mm$ and PCM tank size is $398{\times}270{\times}26\;mm$. The objective was elapsed time lower than maximum operating temperature. Experimental condition, in order to study the effects of the phase-change phenomenon, carried out the various mass flow rate, input electric power, and heat of fusion temperature of two type PCMs. For the above experimental conditions, the cooling performance by using the latent heat showed that heat absorption rate performs for about 3 hours from using PCM $38^{\circ}C$. However, cooling performance by using PCM $50^{\circ}C$ showed higher than surface temperature of heater block because of heat of fusion.

• 펄프종이기술
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• 제38권2호
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• pp.1-8
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• 2006

In this study a process simulation method was used to analyze the accumulation phenomena of anionic starch in the process white water as the closure level of a fine paper making process is increased. A pilot paper machine was used as a model process. Dynamic simulations of the influence of white water usage ratio and uncoated broke addition ratio on the variation of process variable was monitored as a function of time. Results from the dynamic simulations showed that the volume of reservoirs affected the dynamic behavior of the process. The dynamic behavior of flow rate and dissolved starch concentration in process units were different from each other. The speed of the change of dissolved starch concentration in process units was depend on the starting point of the change of dissolved starch concentration, the length of circulation loop, and the volume of reservoirs.

• 한국조경학회:학술대회논문집
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• 한국조경학회 2007년도 Journal of Landscape Architecture in Asia Vol.3
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• pp.214-219
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• 2007

Psychological and physiological effects of plants were studied by investigating human responses while observing plants. Eighteen healthy adult male(aged between $19{\sim}25$ years) participated in this study. Semantic differential method(SD method) and multi-channel near-infrared spectroscopy(NIRS) were used to survey verbal and non-verbal response, respectively. Cerebral hemodynamics as a new evaluation index of brain activity was recorded for right brain hemisphere where visual information is mainly delivered. Thirty seconds of cerebral blood flow in forty seven channels were calculated when watching five types of picture images with different rates of hedge against gray block wall; 0:10, 3:7, 5:5, 7:3, 10:0. In the SD results, similar evaluations were found in all subjects. However, the change of cerebral hemodynamics as a non-verbal response varied among subjects. Largely two patterns of hemodynamics change were found with increasing plants rate in picture images; group A showed significant decreases of blood flow volume in many cortical regions, Group B had significant increase of blood flow volume in the occipital region for the scenes seen comparatively more plant. Our findings on the cerebral hemodynamics may indicate that there are two patterns of brain activity during observation of plants; group A in which brain areas associated with visual information and thinking work simultaneously to the visual stimuli; group B in which brain areas associated only with visual information work.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제50권4호
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• pp.197-205
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• 2024

Objectives: To evaluate the effectiveness of decompression and various parameters that may affect volume change in cystic lesions. Patients and Methods: This retrospective study included patients who visited the Department of Oral and Maxillofacial Surgery at Ewha Womans University Medical Center between 2012 and 2022 for decompression of cystic lesions of the jaw. To measure volume changes, pre- and post-decompression cone-beam computed tomography was performed and reconstructed in three dimensions using Mimics 25.0 software (Materialise NV). A comparative analysis was performed based on sex, age, initial cyst volume, location, degree of cortical layer expansion, and pathologic diagnosis using the Mann-Whitney U and Kruskal-Wallis tests. Results: In all 20 cases, the duration of decompression was 7.84±3.35 months, and all patients successfully completed the decompression period without any complications. Significant differences were observed in the reduction rate and shrinkage speed based on the degree of cortical layer expansion. However, only the shrinkage speed (not the reduction rate) showed a significant difference with respect to the initial cyst volume. Significant differences were not observed based on sex, age, location, or pathologic diagnosis. Conclusion: Although the present study involved a small number of cases, the effectiveness of decompression was confirmed. In particular, 3D analysis overcame the shortcomings of previous studies of decompression and allowed earlier resection. Further studies with more patients are required to provide a rationale for these results and identify factors that influence decompression.

• 대한교통학회지
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• 제21권2호
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• pp.17-31
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• 2003

신호교차로에서 우회전 공용차로의 통과교통량은 여러 가지 요인에 영향을 받기 때문에 복잡하다. 본 연구는 기존의 용량분석에서 고려하지 못하고 있는 공용차로의 폭이 우회전 공용차로 통과교통량에 미치는 영향을 분석한다. 우회전 전용차로가 있는 경우와 순수하게 공용차로로 운영되는 경우의 중간단계에 있는 경우를 대상으로 한다. 공용차로의 폭원별로 이동류별 교통량, 차두시간. 손실시간, 여유폭 이용율을 분석하였으며 주요 결과로는 공용차로의 폭이 갓길을 포함하여 4.1m이상일 때 통과교통량 증가가 나타나기 시작하였으며, 4.6m일 때 한국도로용량편람 방법에 의한 통과교통량보다 2배 이상 큰 것으로 분석되었다.

• E2M - 전기 전자와 첨단 소재
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• 제8권2호
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• pp.229-236
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• 1995

Multimedia has created a system environment that needs a combination of diverse peripherals, faster I/O, and easier configuration. The sheer volume of data one can expect with multimedia hardware and applications storage systems of higher capacity and faster data transfer rate. Unlike the magneto-optical(MO)disk technology which uses bias magnetic field in writing, both the reading and the writing in the phase change (PC) technology are performed only by laser light. In PC optical media, an active layer is reversibly converted between amorphous state and crystalline state by changing irradiation conditions of focused laser beam. Thus, as compared with MO disk, the PC disk has such great advantages that signals can be reproduced by change of reflectance of laser beams in the same manner as the compact disc. The reflectivity of a phase-change spot can be altered in a single pass under the head only through modulation of laser power. The principles and the current status of phase-change optical recording media combined with possible applications are discussed in the present article.

• 한국화재소방학회논문지
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• 제32권1호
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• pp.16-23
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• 2018

다양한 밀폐 구획을 대상으로 내부 체적 및 화재성장률의 변화에 따라 최대 열발생률의 예측이 가능한 상관식이 수치적으로 검토되었다. 구획의 체적은 ISO 9705 화재실의 바닥면 형상을 기준으로 길이 비의 변화를 통해 조절되었으며, 이때 천장 높이는 2.4 m로 고정되었다. 주요 결론으로서, 천장 높이의 변화가 고려된 선행연구 결과와의 비교를 통해, 천장 높이의 변화가 최대 열발생률에 미치는 영향이 검토되었다. 또한 밀폐된 구획에서 천장 높이 변화와 관계없이 최대 열발생률을 예측할 수 있는 보다 일반화된 상관식이 제안되었다. 이 상관식은 수치결과와 비교할 때 다양한 화재성장률에 대하여 평균적으로 7%, 그리고 최대 19%의 오차를 갖는 것으로 확인되었다. 마지막으로 국내 성능위주설계에 적용된 5개의 대표적인 구획을 대상으로, 제안된 상관식의 적용 가능성이 검토되었다. 본 연구결과는 화재시뮬레이션에서 요구되는 입력정보 뿐만 아니라, 밀폐된 공간에서 플래시오버에 의해 야기될 수 있는 최대 열발생률의 예측에 관한 유용한 정보를 제공할 것으로 기대된다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.180-185
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• 2000

Nano crystalline or non-crystalline particles have been widely used in various industrial area, such as ceramics, catalysis, electronics, metallurgy and optic device. In all applications, synthesizing the particles as small as possible and controlling the crystalline phase according to its purpose are necessary for the enhancement of processing performance. In some cases, non-agglomerated particles may be necessary for solving the packing problems. This motivates our attempt of controlling size, morphology, phase of nano titania and silica particles. If one can enhance sintering rate of small aggregates independently of collision rate, one may expect that original aggregates can be changed into volume equivalent spheres and thereby the decrease of collision frequency due to the change leads to much smaller rate of growth of the particles. This is the basic idea of our control strategy.