• 펄프종이기술
• /
• 제38권1호통권113호
• /
• pp.62-69
• /
• 2006

This study was carried out to measure and analyze the storage condition, distribution route, and packaging method of four selected agricultural products(small tomato, cabbage, peach, and carrot) in the cold chain system. It was shown that dew-forming phenomenon by fruits and vegetables deteriorates the agricultural product quality and physical properties of corrugated fiberboard box during the cold chain system. The compressive strength deterioration in corrugated fiberboard boxes was much greater for single wall(SW) corrugated fiberboard containers than for double wall(DW) in low temperature-high humidity condition. To reduce the deterioration of box and dew-forming phenomenon, water-repellency treatment should be over $R_6$. However, water-resistant treatment of corrugated fiberboard containers would be effective under high relative humidity conditions more than 75% RH. It was suggested that functional corrugated fiberboard box packaging would be an optimum method to reduce the deterioration of agricultural products quality by. It was also achieved controlling the relative humidity and temperature during the storage and physical distribution process.

• 설비공학논문집
• /
• 제1권3호
• /
• pp.203-209
• /
• 1989

This paper is an experimental study on the pleasantly suitable cool/warm air conditioning system in order to minimize the energy consumption by attaching the electronic-controlled device to the heat pump air conditioning system.While the cool/warm air conditioning, the air temperatures in the entrance and exit of the indoor heat exchangers should be checked and when the surface of heat exchanger is reached to the dew point temperature, a speed of the compressor is to be automatically controlled by anti-dewing system in order to minimize the energy consumption.At the result of this study, the energy consuming amount is saved about 5% more than that of the conventional air conditioning system by prevent unnecessary dew forming.

• 한국건축시공학회지
• /
• 제12권2호
• /
• pp.243-256
• /
• 2012

This study is the experimental study to improve the insulation of the fastening unit system, which has the most vulnerable insulation in the curtain walls. The Fastening Units were designed and fabricated to minimize the connection part of mullions. In addition, slight movements were taken into account and the performance of the middle layer was evaluated by forming an insulation layer with the vibration-proof rubber and the silicon to satisfy the mechanical and thermal performance criteria. A total of 10 experiments were performed under various conditions, such as indoor-outdoor temperature difference, type of insulation material, thickness of insulation material, and others. using the fabricated Fastening Units. As a result, the vibration-proof rubber insulation showed the temperature difference of $2.2^{\circ}C-5.0^{\circ}C$, and the silicon insulation showed the temperature difference of $2.8^{\circ}C-4.5^{\circ}C$, compared to the non-insulated Fasteniirature difference, typesng Units. When these results were compared with the psychometric chart graph, the insulated Fastening Unit designed in this study can be considered to prevent the dew condensation.

• 한국환경과학회지
• /
• 제30권11호
• /
• pp.925-936
• /
• 2021

The study was aimed to investigate the correlation between tidal effects and fog occurrence in Incheon and Mokpo, which are located in the middle and southern coasts of the West Sea of Korea, respectively. The investigation used meteorological data obtained from the automated synoptic observing systems and automatic weather stations and ocean data from tide stations from 2010 to 2019. Fog occurrence frequency was highest at high tide (Incheon, 41%; Mokpo, 45%). During fog event days at high tide, the dew-point depression was low (Incheon, 0.5℃; Mokpo, 0.4℃) and the relative humidity was high (Incheon, 97%; Mokpo, 98%). The wind speed was 2.4 m/s in Incheon and 2.0 m/s in Mokpo, and the main wind directions were west-southwesterly from Incheon and southwesterly from Mokpo. In the fog case study, tidal flats were covered with water before and after the fog started. During the fog period, both stations experienced negative air-sea temperature differences, low dew-point depression, and high relative humidity were maintained, with weak winds forming from the tidal flats to the shore.

• 설비공학논문집
• /
• 제11권4호
• /
• pp.448-456
• /
• 1999

Variations of thickness and effective thermal conductivity of frost forming on the horizontal] cylinder with respect to time were measured under cross flow. The local heat flux around the cylinder was determined by measuring the radial temperature distribution in the cylinder having small holes drilled axially in which T-type thermocouples were inserted, then by using one dimensional cylindrical heat conduction equation. The thickness and the surface temperature of the frost layer around the cylinder were measured periodically while developing the frost. Each experiment was peformed by varying the Reynolds number, the temperature, and the humidity condition. Specially the dew point temperature of the most cases was below the freezing point. Experimental data showed that the frost layers on the front and the rear surface were thicker than those on the top and the bottom one which was near the separation point. The thickness and effective thermal conductivity of the frost layer were affected by inlet air velocity, temperature, and humidity. Moreover, the effective thermal conductivity and the effective thermal resistance increase with respect to time.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2000년도 춘계학술대회논문집B
• /
• pp.240-245
• /
• 2000

In this study, thickness, density and effective thermal conductivity of frost forming on the horizontal cylinder were measured with various air temperature and humidity. Reynolds number and temperature of cooling surface are controlled 17300 and $-l5^{\circ}C$ respectively. In each case of air temperature $5^{\circ}C,\;10^{\circ}C,\;15^{\circ}C,$ varying absolute humidity, experiments were executed. In measuring frost surface temperature and thickness of frost layer, infrared thermocouples and CCD camera were used. Frost was gathered from cylinder to measure mass of frost layer. Experimental data showed that the thickness and effective thermal conductivity of the frost layer increase with respect to time. Thickness of frost layer increase with humidity increasing, and density of frost layer increase with air temperature rising. Frost growth with air temperature and density of frost layer with humidity are affected by whether dew point is below or above freezing point.

• 한국산학기술학회논문지
• /
• 제16권4호
• /
• pp.2391-2400
• /
• 2015

내후성 강재는 대기환경에서 내식성이 우수하여 강교량의 재료로 많이 사용되고 있다. 그러나 내후성 강은 해수와 가까운 지역, 음지 및 습도가 높은 환경에서는 안정된 녹층이 형성되지 않고, 일반녹이 발생하고 있다. 따라서 열악한 대기환경을 가지는 일본에서는 무도장으로 사용하지 않고, 녹안정화 처리를 하고 있는 상황이다. 그러나 국내에서 건설된 내후성 강은 대부분 무도장으로 건설되었고, 건습의 주기적인 반복이 일어나기 어려운 밀폐형 박스거더형으로 건설되었다. 특히, 한강수변위에 건설된 강교량의 경우, 수분의 증발, 온도차에 의한 결로 및 우수에 의한 체수 등으로 내후성강의 부동태 피막형성에 해로운 영향을 미치고 있다. 이에 따라, 본 연구에서는 상수도 보호구역에 무도장 내후성 강으로 건설된 교량의 밀폐형 박스거더 내부의 부식 특성을 분석하기 위하여, 육안에 의한 관찰, 셀로판 테이프 시험, 강재 두께 측정, 표면 부식 전위측정, 채취한 녹의 전자현미경 분석 및 X선 회절 분석을 실시하였다. 분석을 통하여, 밀폐형 박스거더 내부에서 불안정녹층이 관찰되었으며, 특히, 상부 및 하부 플랜지의 경우 우수에 의한 체수, 결로 및 제설제에 의한 영향 등으로 부식 정도가 심하게 관찰되었다.

• 한국지구과학회지
• /
• 제31권3호
• /
• pp.288-299
• /
• 2010

본 연구는 과학적 소양은 과학적 지식의 획득과 과학적 담화에 참여할 수 있는 언어적 능력을 통하여 길러진다는 전제하에 대기 중의 물의 상태변화에 관한 학생 글에서 나타나는 의미관계와 과학 언어적 특징을 알아보았다. 중학교 3학년 학생 67명이 참여하여 일상생활에서 흔히 경험할 수 있는 현상과 학교과학교육에서 체계적으로 배우는 현상 에 관한 두 개의 서술형 문항에 대한 글을 작성하였다. 연구의 결과 학생들은 '이슬점' 같은 생소한 용어뿐만 아니라 '수증기', '김' 등과 같은 친숙한 용어에 대해서도 잘못된 의미관계를 형성하고 있었고, 학교과학 교육보다 일상의 경험에서 형성된 지식에서 옳은 의미관계와 잘못된 의미관계 모두 더 많이 나타났다. 일상의 과학적 현상에 대해서는 행위와 절차를 중심으로 한 서술 양상이, 학교 교육에 의해 접하게 된 현상에 대해서는 전문용어와 명사구의 사용 양상이 보였다. 본 연구를 통하여 경험에 기초한 자발적 과정은 풍부한 의미관계 형성에, 형식적이고 이론적인 과정은 명사화를 중심으로 한 전문적이고 추상적인 서술의 측면에서 과학적 언어 능력 발달에 기여함을 알 수 있었다.