• 한국축산식품학회지
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• 제36권1호
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• pp.100-108
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• 2016

Microbiological contamination of eggs should be prevented in the poultry industry, as poultry is one of the major reservoirs of human Salmonella. ClO₂ gas has been reported to be an effective disinfectant in various industry fields, particularly the food industry. The aims of this study were to evaluate the antimicrobial effect of chlorine dioxide gas on two strains of Salmonella inoculated onto eggshells under various experimental conditions including concentrations, contact time, humidity, and percentage organic matter. As a result, it was shown that chlorine dioxide gas under wet conditions was more effective in inactivating Salmonella Enteritidis and Salmonella Gallinarum compared to that under dry conditions independently of the presence of organic matter (yeast extract). Under wet conditions, a greater than 4 log reduction in bacterial populations was achieved after 30 min of exposure to ClO₂ each at 20 ppm, 40 ppm, and 80 ppm against S. Enteritidis; 40 ppm and 80 ppm against S. Gallinarum. These results suggest that chlorine dioxide gas is an effective agent for controlling Salmonella, the most prevalent contaminant in the egg industry.

• 대한기계학회논문집B
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• 제26권2호
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• pp.253-260
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• 2002

It is known that frost formation on surfaces of the heat exchanger seriously affects the performance of the refrigeration system. Accordingly, defrosting should follow, and effective defrosting is possible only when both analytic tools and comprehensive experimental data on frost formation are assailable. An experimental investigation was undertaken to characterize the effect of environmental parameters on frost formation on a horizontal cylinder in cross uniform flow. Several experiments were carried out with various environmental parameters such as inlet air temperature, inlet air humidity, air velocity and cooling surface temperature. Frost thickness, mass, surface temperature and cylinder inner and outer temperature were measured at front and rear positions of the cylinder. Thickness, mass, density, and effective thermal conductivity of the frost layer were obtained from measured data and effects of environmental parameters on the frost formation were analyzed. Data from experiments were correlated using dimensionless variables.

• 생물환경조절학회지
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• 제25권4호
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• pp.277-282
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• 2016

본 연구는 폭 7m, 길이 25m, 동고 3.2m의 토마토를 재배하는 온실에 공기순환팬을 설치하고 순환팬이 온실 내 온도 및 습도 분포에 미치는 영향을 조사하였다. 기존의 순환팬 설치 기준(ASAE, 1997)을 참고하여 시험온실에 순환팬 10대를 2열 및 다른 방향으로 설치하여 18시부터 다음날 8시까지 온실 내 온습도를 측정하였다. 온실 내 온습도는 온실을 9개의 격자망으로 나눈 후 온실 중앙부에서는 0.7m, 1.7m 및 2.7m 높이, 온실 좌우측에는 0.7m, 1.7m 높이에 센서를 설치하였다. 공기순환 팬을 사용하지 않았을 때 온실 상하부의 온도 및 습도의 평균값은 $14.7^{\circ}C$, 74.8%와 $13.0^{\circ}C$, 85.6%로 온습도 차는 평균적으로 $1.7^{\circ}C$, 10.8% 발생하였다. 공기순환팬 10대를 2열 및 다른 방향으로 설치하여 운용했을 때 온실 상하부의 온습도는 $14.6^{\circ}C$, 75.9%와 $14.5^{\circ}C$, 79.1%로 온습도 차는 각각 $0.1^{\circ}C$, 3.2%였으며 순환팬을 사용하지 않았을 때와 비교하여 온실 상하부의 온도 및 습도 차가 감소하였다. 순환팬을 6대 및 5대로 줄여서 운용했을 때 온실 상하부의 온습도 차는 각각 $0.3^{\circ}C$, 3.4%와 $0.3^{\circ}C$, 4.0%로 나타나 순환팬 10대를 사용했을 때와 비슷한 효과를 보였다. 순환팬 10대를 2열 및 같은 방향으로 설치했을 때의 온실 상하부의 온습도 차는 $0.5^{\circ}C$, 4.9%로 팬을 다른 방향으로 설치했을 때보다 온습도 차가 크게 나타났다. 온실 좌우측면, 전후면의 온습도 차를 살펴보면 순환팬을 사용하지 않았을 때 좌우 측면의 온습도 차는 $0.3^{\circ}C$, 1.7%로 작아 팬을 사용했을 때와 큰 차이가 없었으나 순환팬을 사용하지 않았을 때 $1.0^{\circ}C$, 4.2%로 나타났던 전후면의 온습도 차는 순환팬을 사용함으로써 감소하였다. 이는 공기순환팬이 온실 내 공기를 순환시켜 온풍난방 시 상부에 정체된 더운 공기나 열손실로 인해 온도가 다른 공기를 교반시킴으로써 온도 및 습도 차가 감소한 것이다. 폭 7m, 길이 25m, 동고 3.2m인 단동온실에서 날개 크기 230mm, 풍량 $11m^3/min$의 공기순환팬을 사용하고자 할 때는 순환팬 5대를 2열로 설치하되 각 열을 방향을 다르게 하고 9m 간격으로 설치하여 운용하는 것이 가장 경제적이고 효과적일 것이다.

• 한국농공학회지
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• 제16권1호
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• pp.3263-3291
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• 1974

Experimental work of grain bin was carried out to develop the methods of natural air in-bin drying and storage. The method is considered to be more economical, labour saving, and an effective countermeasure to grain loss. To examine the possibility of farm use of the grain bin and to analyze the related factors concerned with in-bin grain drying and storage, ambient air conditions (especially the change of air temperature and relative humidity) and grain quality during drying and storage periods were investigated. A laboratory model bin was constructed to investigate the effect of different forced air conditions on the drying characteristics of rice. In addition, a grain bin with 2.2m diameter and 1.8m height, considered to be the optimum size for the average Korean farm, was constructed and tested to examine the drying and storing characteristics of rice. The weather data analyzed in this study was the nine-year (from 1964 to 1972) record of air temperature and relative humidity in the Suweon area, and the thirty-year (from 1931 to 1960) record of pentad normal relative humidity and air temperature in the Seoul area. From the results of the weather data analyses, the adequate air delivery hours (which was arbitrary defined as the condition to give less than 75% relative humidity) to dry the rice during October were about nine hours (from approximately 10 A.M. to 7 P.M, ) a day, in which the average air temperature was about 15.9$^{\circ}C$ and average relative humidity was 66%. The occurence of days having three hours of such conditions was 1, 2, and 1-day within the 1st, 2nd add last 10-day periods for the month of October, respectively. Therefore, it may be considered that the weather condition in October was satisfactory for the forced natural air drying. The results of the laboratory model bin test were analyzed to obtain the drying curve and drying rate for different drying stages and grain layers in the bin corresponding to various conditions of forced natural air. A drying experiment with a prototype grain bin showed that an approximate 5 percent grain moisture gradient through a 1.6 meter grain deposit was observed after 80 hours of intermittent drying, giving an over dried zone in the lower grain layers and an extremely high grain moisture zone in the upper layers. This indicates that an effective measure should be taken to reduce this high moisture gradient. In order to investigate the drying characteristics of bulk grain in a layerturning operation a grain bin test was performed. This showed a significant improvement of uniform drying. In this test, approximate 107 hours were required to dry a depth of 1.6 meter of grain from an initial moisture content of 22.2 percent to a moisture content of 16.7 percent using an air delivery rate of 2.8 cubic meter per a minute per every cubic meter of grain. This resulted in a 2 percent moisture gradient from the top to the bottom of the bin. During storage period, till the end of June the average temperature of grain was 2~3$^{\circ}C$ higher than ambient air temperature. But during July when the grain moisture content went up slightly (less than 1 percent), the average temperature of the grain also increased to 3~5$^{\circ}C$ higher than ambient air temperature. It is therefore recommended that for safe grain storage, grain should not be stored in sheet metal bins after mid May. From the above results, in-bin rice drying and storage can be used effectively on Korean farms. It is strongly recommended that the use of grain-bin system should be implemented for farm use to improve farm drying and storage of rice.

• 생물환경조절학회지
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• 제3권1호
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• pp.58-65
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• 1994

본 시험은 하절기 경제성을 고려한 효율적인 온도하강방법을 구명하고자 차광재료, fog system, 송풍등 복합적 온도하강처리에 따른 비닐하우스의 기상환경변화를 조사하여 다음과 같은 결과를 얻었다. 1. 중형하우스에서 온도하강방법에 따른 환경특성은 처리에 따라 하우스의 고온화를 상당히 효율적으로 억제하였다. 7월31일 하우스냉방처리에 따른 기온의 일중변화를 경시적으로 보면 수분의 증발잠력능력을 이용한 fog system과 은색차광 및 송풍을 혼합하여 처리할 경우 기온과 지온은 외기온에 비하여 최고 각각 1$0^{\circ}C$, 4$^{\circ}C$정도 온도하강효과가 있었으며 그 다음은 은색차광＋fog system, 은색차광＋송풍, 흑색차광＋송풍구 순이였다. 2. 하절기 가장 온도가 높은 시기인 7월20일부터 8월21일까지 하우스냉방처리에 따른 온도하강 효과를 보면 최고기온은 시험처리에 따라 온도차가 인정되며 은색차광＋fog system＋송풍구의 지상, 지표면기온은 외기온에 비하여 각각 약 8$^{\circ}C$, 7$^{\circ}C$정도 온도하강 효과가 있었다. 3. 은색차광＋송풍구와 흑색차광＋송풍구의 일사량은 청명한날 외기일사량에 비하여 각각 약 29.3%, 32.5%이였으며 흐린 날은 각각 약 27.4%, 31.8%이였다.

• 한국자원식물학회지
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• 제23권4호
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• pp.379-385
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• 2010

농가현장에서 이끼재배에 활용할 수 있는 기존의 연구자료가 거의 없는 실정에서 분화식물로서 관상가치가 높은 나무이끼의 재배기술을 개발하고자 투명용기 재배시 토양 습도, 적정 공기노출 정도구명, 적정 용토 구명, 지피용 이끼선발 등 상품화에 관한 연구를 수행하였다. 나무이끼의 투명용기 재배시 용기내에 수분을 적습(수분 60~80%)으로 관리하는 것이 좋으며 용토는 피트모스:펄라이트(7:3)의 상토에서 좋았고 공기노출 정도에 있어서는 완전밀폐와 10% 노출에서 생육이 좋았다. 용기의 공기유통 정도를 나타내는 천공형태는 상부천공 2구에서 생육이 좋고 내부에 습기가 맺히지 않았다. 투명 용기내의 적정 용토는 수태, 피트모스, 피트모스+펄라이트 구에서 생육이 좋았으나 수태는 가격이 비싸 경제성이 떨어지므로 피트모스나 피트모스+펄라이트 상토가 유리한 것으로 나타났다. 나무이끼와 어울릴 수 있는 지피용 이끼로는 솔이끼, 편평털깃털이끼, 깃털이끼, 털깃털이끼, 아기초롱이끼, 은이끼, 가는털깃털이끼, 표주박이끼, 흰털이끼, 꼬마이끼 등 10종 모두 초장이 0.7~2.7 cm로 나무이끼보다 1 cm이상 작아 지피용으로 적당한 것으로 나타났다.

• 대한안전경영과학회지
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• 제13권4호
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• pp.109-116
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• 2011

This study examined into property of flour dust explosion to get the basic data for safety of industry by protecting accident of dust explosion. The experiment was conducted to know the effect of distance between explodes in the experiment device, effect of flour dust concentration, effect of humidity, effect of explosion pressure to the dust concentration and effect of inactive substance additive. The study indicated that explosion was happened effectively at the optimum distance 100mm or less in inter-polar distance, and minimum ignition energy was measured at 6mm. The data of feed concentration to the probability of explosion showed that the smaller the particle diameter was, the larger probability of explosion was, and the higher the dust concentration was, the more increased the pressure of explosion was, but more than upper limit of dust concentration, then the explosion of pressure decreased. For the effect of humidity, the more it contained water, the more decreased the ignition energy of dust was, so increased minimum explosive concentration, and effective water content was minimum 10% or more. Inactive substance additive was effective in adding more than 15% CaCO3 and CaO as substance inhibiting dust explosion, in which CaCO3 was more effective than CaO. the analysis of the flame of dust explosion was performed by high-speed video camera, it showed the size of flame bacame smaller in order that sub feed, main feed, wheat powder. As a result, sub feed was expected to be less dangerous than others.

• 전기학회논문지P
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• 제62권2호
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• pp.103-109
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• 2013

In this study, the three sounds effects on subjects due to EEG type, and it researched to find optimal sound to increase their amenity and productivity. EEG and HRV were compared and analyzed in the environmental test room by classifying subjects into two type: A and B. The condition of the environmental test room was in temperature $31[^{\circ}C]$, relative humidity 50[RH%], air current speed 0.02[m/s] and illuminance 1000[lux] with setting up three different sounds which are U type sound, V type sound and Z type sound. The result of this study, at U type sound for A and B type, relative $M{\alpha}$ wave, relative $M{\beta}$ wave and SEF50 were revitalized. Also at Z type sound for A and B type, stress index, fatigue degree and HRT were decreased and SDNN was revitalized. Therefore U type sound is very effective to increase amenity, productivity and concentration, and Z type sound is very effective to decrease stress and fatigue degree.

• 대기
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• 제20권4호
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• pp.427-436
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• 2010

The single-scattering optical properties of ice crystals in cirrus clouds by the aircraft measurement data were investigated, and the radiative equilibrium temperatures and radiative fluxes were calculated and analyzed by radiative convective model with the variations of ice crystal habits and sizes in cirrus clouds. The homogeneous cloud is assumed to be in the layer 200~260 hPa with an ice crystal content of $10gm^{-2}$ for the flux calculation. The profiles of temperature, humidity, and ozone typical of mid-latitude summer are used. The surface albedo is assumed to be 0.2 for all spectral bands and the cosine of solar zenith angles is 0.5. The result of radiative equilibrium temperature at surface was less than surface temperature of the standard atmosphere data in case of smaller effective ice crystal size and larger optical thickness. The column, aggregation and plate in 6 ice crystal habits were the most effective in positive greenhouse effect and bullet-4 was the worst in it. At the surface, the maximum difference of equilibrium temperature by 6 kinds of ice crystal habits were about 3~15 K with 30 sample aircraft measurement data.

• 한국자동차공학회논문집
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• 제25권3호
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• pp.336-343
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• 2017

Intake air conditions, such as air temperature, pressure, and humidity, are very important parameters that influence engine performance including combustion and emissions characteristics. The purpose of this study is to investigate the effects of intake air temperature on combustion and exhaust emissions characteristics in a single cylinder diesel engine. In this experiment, an air cooler and a heater were installed on the intake air line and a gas flow controller was installed to maintain the flow rate. It was found that intake air temperature induced the evaporation characteristics of the fuel, and it affects the maximum in-cylinder pressure, IMEP(indicated mean effective pressure), and fuel consumption. As the temperature of intake air decreases, the fuel evaporation characteristics deteriorate even as the fuel temperature has reached the auto-ignition temperature, so that ignition delay is prolonged and the maximum pressure of cylinder is also reduced. Based on the increase in intake air temperature, nitrogen oxides(NOx) increased. In addition, the carbon monoxide(CO) and unburned hydrocarbons(UHC) increased due to incomplete fuel combustion at low intake air temperatures.