• 설비공학논문집
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• 제9권2호
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• pp.163-170
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• 1997

Solubility on $(LiBr+CaCl_2)$ in water has been measured systematically and compared with those of pure LiBr. It has been observed that there exists optimum value of $CaCl_2(LiBr+CaCl_2)$ in solubility when total$(LiBr+CaCl_2)$ concentration is higher than 57wt%. As total concentration increases up to 65wt%, it is found that the optimum value also increases monotonically. From the experimental results, a master plot has been constructed, with which optimum ratio of LiBr to $CaCl_2$ can be found in terms of total concentration. Vapor pressure of $H_2O/(LiBr+CaCl_2)$ solution with optimum contents of $CaCl_2$ has been observed to be changed negligibly at relatiely low temperature. However, as temperature increases, it is found that increasement in vapor pressure is significant.

• 한국의류학회지
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• 제17권1호
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• pp.151-161
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• 1993

The purpose of this study was to investigate the effect of hydrophilic finish for polyester (PET) fabric and hydrophobic finish for cotton fabric on the water transport and comfort properties. Polyester fabric was treated with 10% sodium hydroxide solution to impart hydrophilicity. Cotton fabric was sprayed with Scotch-gard$^{(R)}$ water and oil repellent finish to impart hydrophobicity. Porosity, air permeability, contact angle, wickability and water vapor transport rate (WVTR) were measured to determine the water transport properties of fabrics. To compare the comfort properties of treated and untreated fabrics, wear test was performed by putting fabric patches on the upper back: stratum corneum water content (SCWC), subjective wettedness and comfort rating were determined. The results were as follows: (1) The contact angle of water on treated polyester fabric was decreased and that of treated cotton fabric was increased. Also, the wickability of treated polyester fabric was increased and the wickability of cotton fabric was decreased. (2) Although each finish did not change porosity, the water vapor transport rate of treated polyester fabric was increased and that of treated cotton fabric was decreased slightly. (3) The results of stratum corneum water content measurements showed good agreement with the results of the contact angle and the wickability, i.e., the better the liquid water transport properties are, the less the stratum corneum water contents were resulted. (4) The realtionship of subjective wettedness or comfort and stratum corneum water content was independent. Therefore, it was concluded that human perception on the subjective wettedness or the comfort is affected by the skin contact of wet fabric rather than by the stratum corneum water content.

• Journal of the Korean Wood Science and Technology
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• 제23권1호
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• pp.54-60
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• 1995

This paper reports on the changes of equilibrium moisture contents and specific surface areas of Poplar wood(Populus euramericana) for various steam explosion treatments. Equilibrium moisture contents(EMC) and specific surfaces of steam exploded woods were measured under the moisture adsorption course at 25$^{\circ}C$, and compared with those of other materials and wood meals. The EMCs of steam exploded wood meal were 1~5% less in comparison with that of wood meal. In the case of delignified steam exploded wood meal and delignified wood meal, the same tendency was appeared too. But absolute values of EMCs for delignified wood meals were larger than those of the wood meal. For the changes of EMC by the steam exploded conditions, the EMC decreased with the increase of the steam explosion pressure. On the other hand, specific surface areas were calculated from BET plots based on amounts of monomolecular vapor adsorption of various wood meals. Specific surface areas of the wood meal and delignified wood meal were 90~145, 34~90($m^2/g$) respectively, and which were greater in comparison with those of steam exploded wood meals and delignified steam exploded wood meals. From these results, it is considered that the amount of water vapor adsorption was decreased by the increase of the crystallinity, effect of heat treatment, and coating by melted lignin in during the steam explosion.

• 한국식품과학회지
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• 제29권2호
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• pp.255-260
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• 1997

이상의 결과에서 글루코만난 필름은 다른 천연 탄수화물고분자들의 필름들에 비해 비교적 우수한 인장 강도와 신장력을 가지며 높은 수분차단력을 보이나, 친수성 필름이 가지는 수분에 대한 민감성 때문에 수분을 직접 접촉할 때 높은 용해도를 보임을 알 수 있었다. 그리고 가소제의 함량의 증가에 따라 인장강도가 낮아지는 대신에 높은 신장력을 나타내었다. 글루코만난 필름은 적절한 여러 조건에 따라 넓은 범위의 물성변화를 가지는 친수성 필름으로서 식품포장산업에서의 다양한 이용가능성이 제시되었으며, 앞으로 적절한 가소제 및 첨가제의 이용, 수분에 대한 내성의 향상등의 연구가 더 필요하리라 사료된다.

• 한국식품과학회지
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• 제15권4호
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• pp.315-320
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• 1983

본(本) 연구(硏究)에서는 국내(國內)에서 아직 조사(調査)되지 않은 16개 품목(品目)의 농산물(農産物)에 대(對)한 등온흡습곡선(等溫吸濕曲線)을 측정온도(測定溫度), $25^{\circ}C,\;30^{\circ}$, 및 $45^{\circ}C$ 에서 결정(決定)하였다. 온도범위(溫度範圍) $25^{\circ}{\sim}45^{\circ}C$ 사이에서는 온도(溫度)의 증가(增加)에 따라 평형수분함량(平衡水分含量)이 감소(減少)하는 경향을 보였다. 또한 등온흡습곡선(等溫吸濕曲線)의 측정치(測定値)로 부터 BET단분자막수분함량(單分子膜水分含量)을 분석(分析), 결정(決定)하였다. 등온흡습기작(等溫吸濕機作)의 열역학적(熱力學的) 함수인 엔트로피의 변화(變化)는 건조식품(乾燥食品)의 안전저장(安全貯藏) 수분함량(水分含量)영역인 BET단분자막수분함량(單分子膜水分含量)과 밀접한 관계(關係)에 놓인 것으로 사료되고 있다.

• Journal of Mechanical Science and Technology
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• 제17권4호
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• pp.581-589
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• 2003

Film absorption involves simultaneous heat and mass transfer in the gas-liquid system. While the non-absorbable gas does not participate directly In the absorption process. its pretence does affect the overall heat and mass transfer. An experimental study was performed to investigate the heat and mass transfer characteristics of LiBr-H$_2$O solution flow ing over 6-row horizontal tubes with the water vapor absorption in the pretence of non-absorbable gases. The volumetric concentration of non-absorbable gas, air, was varied from 0.17 to 10.0%. The combined effects of the solution flow rate and its concentration on the heat and mass transfer coefficients were also examined. The presence of 2％ volumetric concentration of air resulted in a 25% reduction in the Nusselt number and 41% reduction in the Sherwood number Optimum film Reynolds number was found to exist at which the heat and mass transfer reach their maximum value independent of air contents. Reduced Nusselt and Sherwood numbers. defined as the ratio of Nusselt and Sherwood numbers at given non-absorbable gas content to that with pure water vapor, were correlated to account for the reduction in the heat and mass transfer due to non-absorbable gases in a falling film absorption process.

• 한국염색가공학회지
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• 제33권1호
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• pp.40-47
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• 2021

As modern society develops, it becomes very complex and diverse, and interests in the convenience of life and the natural environment are gradually increasing. Products used in our daily life are also changing according to the needs of consumers, and food packaging is one of them. In particular, retort packaging materials have been used for the purpose of long-term preservation of contents, but the appearance of products suitable for recent environmental issues has been somewhat delayed. Therefore, in order to develop eco-friendly and human-friendly products by replacing the metals used in the existing retort packaging materials, the possibility of substitution was examined using cellulose nanofibers, a natural material. As a result, it can be seen that all functions can be replaced according to the existing long-term storage characteristics for retort packaging films. In particular, not only oxygen permeability and water vapor permeability, which are one of the most important factors, but also heat resistance, which is heating durability, is evaluated as applicable to commercialization compared to products using metals currently in use.

• 한국포장학회지
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• 제29권1호
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• pp.43-49
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• 2023

본 연구에서는 CasNa/CL의 물리적 특성을 개선하기 위하여 BN을 충진제로 활용하여 CasNa/CL/BN코팅제 및 코팅지들을 제조하였다. BN의 함량변화에 따라 제조한 CasNa/CL코팅지와 CasNa/CL/BN코팅지들의 화학적 및 형태학적 특성을 분석하였고, 기계적강도, 수증기차단특성, 표면특성, 항산화특성에 대한 분석을 통해 포장소재로써 적용 가능성을 확인하였다. SEM분석결과, CasNa/CL코팅지 표면에서 핀홀 현상이 발생하는 것을 확인하였다. 하지만, BN함량이 증가함에 따라 핀홀 현상은 감소되는 경향을 보였고 표면거칠기는 증가되는 경향을 확인할 수 있었다. BN 함량이 증가함에 따라 CasNa/CL/BN코팅지들의 연신률 및 수증기차단성이 개선되는 것을 확인할 수 있었다. BN함량 증가에도 불구하고 CasNa/CL/BN코팅지들의 항산화특성은 CasNa/CL코팅지와 유사한 경향을 보임을 확인하였다. 자연유래소재인 CasNa, CL 및 BN을 활용한 코팅지의 경우 친환경 포장소재로써 활용이 가능할 것으로 판단되지만, CL 및 BN과 CasNa와의 혼화성 및 분산성 개선 방안에 대한 추가적인 연구가 필요함을 확인하였다.

• 한국농공학회논문집
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• 제61권5호
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• pp.101-108
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• 2019

The domestic duck industry is the sixth-largest among the livestock industries. However, 34.3% of duck houses were the duck houses arbitrarily converted from plastic greenhouses. This type of duck house was difficult to properly manage internal air temperature and humidity environment. Humidity environment inside duck houses is an important factor that directly affects the productivity and disease occurrence of the duck. Although the humidity environments of litters (bedding materials) affect directly the inside environment of duck houses, there are only few studies related to humidity environment of litters. In this study, evaporation rates from litters were evaluated according to air temperature, relative humidity, water contents of litters, and wind speed. The experimental chamber was made to measure evaporation rates from litters. Temperature and humidity controlled chamber was utilized during the conduct of the laboratory experiments. Using the measured data, a multi linear regression analysis was carried out to derive the calculation formula of evaporation rates from litters. In order to improve the accuracy of the multi linear regression model, the partial vapor pressure directly related to evaporation was also considered. Variance inflation factors of air temperature, relative humidity, partial vapor pressure, water contents of litters, and wind speed were calculated to identify multicollinearity problem. The Multiple $R^2$ and adjusted-$R^2$ of regression model were calculated at 0.76 and 0.71, respectively. Therefore, the regression models were developed in this study can be used to estimate evaporation rates from the litter of duck houses.

• 한국산업보건학회지
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• 제1권2호
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• pp.136-143
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• 1991

Inorganic mercury in urine and airborne was determined by cold vapor atomic absorption spectrophotometry. Detailed sampling methods and analylical results are as follows : 1. 100~200ml of urine for each person was taken in 250 ml borosilicate bottle and $K_2S_2O_8$ (0.1g/100ml urine) was added to prevent bacterial contamination. About 1001 air of workingplace was absorbed in l0ml of absorbing solution. Urine samples and absorbing solution tubes were stored at $4^{\circ}C$. Dillution solution to prepare standard solution used deionized water (D.W) for urine and absorbing solution (A.S) for air. 2. 1n this procedure deteclion limit was 1ng/ml and mercury contents of blank reagent solution was 1~2ng/ml. 3. Calibration range was $0.02{\sim}0.1{\mu}g/ml$ and in this range r.s.d for each calibration curve in D.W and A.S and ${\pm}7.9%$ and ${\pm}3.7%$, respectively. 4. Repeatability (n=5 times, conc. $0.05{\mu}g/ml$) was ${\pm}5.8%$, in D.W. and ${\pm}4.4%$ in A.S, respectively. 5. Recovery for urine adding spiked concentration ($0.05{\mu}g/ml$) was about 90%. 6. Analytical result of samples was $1{\sim}139{\mu}g/l$ in urine and ${\sim}0.127mg/m^3$ in airborne.