• Journal of Bio-Environment Control
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• v.10 no.1
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• pp.10-14
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• 2001

The cooling effect of a fog cooling system has a close relationship to air flow and relative humidity in the greenhouse. From the VETH chart for cooling design, a cooling efficiency can be improved by means of increasing the air exchange rate and the amount of sprayed water. In the no shading experimental greenhouse by time control, when average air exchange rate was 0.77 times.min$^{-1}$ and spray water amount was 2,009g, inside temperature of the greenhouse was 31$^{\circ}C$ that was almost close to outside temperature and cooling efficiency was 82%. When average air exchange rate was close to temperature of the greenhouse that was no cooling and 70% shading greenhouse environment. When average air exchange rate was 2.59times.min$^{-1}$ , spray water amount was 2,009g and shading rate was 70%, inside relative humidity of the greenhouse was increased was 2,009 g and shading rate was 70%, inside relative humidity of the greenhouse was increased, but temperature was not decreased. When average air exchange rate was 2.33 times.min$^{-1}$ and spray water amount was 2,009g, inside temperature was 31.4 and at that time maximum wind speed at the air inlet of greenhouse was 1.9m.s$^{-1}$ . Since time controller sprayed amount of constant water at a given interval, some of sprayed water remained not to be evaporated, which increased relative humidity and decreased cooling efficiency. Because the shading screen prevented air flow in the greenhouse, it also caused the evaporation efficiency to be decreased. In order to increase cooling efficiency, it was necessary to study on controling by relative humidity and air circulation in the greenhouse.

• Hwankyungkyoyuk
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• v.3 no.1
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• pp.55-62
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• 1992

In the orient, ancestor's perception to natural environment was related on the change of climate. Man had been a essence of the warm blood animal, which had suited in mild climate for living and acting. The weather of hot or cold was not only comfort in human life but influences negatively on human behavior. The most people of oriental was particularly interrelated to seasonal change of climate in earlier time. Because, there are elements such as temperature, humidity and wind in the category of climate, these elements differentiated seasonal change. The main methods of perception of natural environment were observed and classified. Although these methods were in the primitive stage, these coincided the tendency of modern science. For example, confucian was recognized the law of vertical air current that warm air rised and cold air sinked. And they could classify all elements nature based on the principles of 'Yin and Yang(陰陽論)' such as male and female, the sun and moon. shade and light etc. Thus results of the observation and the classification concerned with physical environment can be utilize a wisdom for progressive life of inhabitants. It was a origin of the education in natural environment. Commonness in the viewpoint of environment in the orient if recognized the law of circulation. Buddhism, originated in india, realized that all of phenomena in the world was changed slowly through the principles of cycle(輪廻說) such as male and female, the sun and moon, shade and light etc. Thus results of the observation and the classification concerned with physical environment can be utilized a wisdom for progressive life of inhabitants. It was a origin of the education in natural environment. Commonness in the viewpoint of environment in the orient if recognized the law of circulation. Buddhism, originated in India, realized that all of phenomena in the world was changed slowly through the principles of cycle(輪廻說). For example, whole of land is shifted from young stage to old stage as the life cycle of humanbeing. The theory of karma effects(葉報設) is so signify with the good result that good one's action is reap a sweet fruit. The most environmental problem in today must realized as a consequence of men's act. Then Taoism emphasized the pure nature without the artificiality. Because complexual environment was composed of several elements, It was maintained through the artificiality. Because complexual environment was composed of several elements, It was maintained through the interaction of cause and effects. The solution of environmental problem is maintenanced the harmony between cause and effects by a philosophical concept.

• Korean Journal of Clinical Pharmacy
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• v.22 no.2
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• pp.160-166
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• 2012

Purpose: The purpose of the present study was to investigate the pharmacokinetics of urea, a new potential diagnosis reagent of Helicobacter pylori infection. Methods: Considering the mechanism of urea breath test, we determined the excretion of urea in expired air after its oral administration in rats and beagle dogs at the dose of 2 mg/kg (including 50 mCi/mmol $^{14}C$-urea 50 ${\mu}Ci/kg$ for rats and 13.5 ${\mu}Ci/kg$ for dogs). Results: Urea was rapidly disappeared from the blood circulation by 1 hr after its i.v. bolus injection, followed by a slow disappearance by 24 hr. The half-lives at the distributive phase ($t_{1/2{\alpha}}$) and post-distributive phase ($t_{1/2{\beta}}$) were 2 min and 6 hr, respectively. The bioavailability of urea was 64.3% after its oral administration. The values of the volume of distribution ($V_{dss}$) and the total body clearance ($CL_t$) after the oral administration were compatible with those after i.v. administration. The recovery of urea in the bile was about 0.1% of the dose by 24 hr after its oral administration. Urea was extensively eliminated in the urine by 48 hr. The recovery ratios of urea in the urine and expired air were about 86.8% and 2.99% of the dose by 48 hr, respectively. Moreover, urea was mostly distributed from the blood circulation to the kidney, followed by being eliminated in the urine without metabolism. The concentration of urea in the kidney was 4.0 times higher than that of plasma at 40 min after its oral administration. Conclusions: These findings indicated that oral route appears to be available for the administration of urea. Orally administered urea, thus, was considered to be useful for the diagnosis of Helicobacter pylori infection.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.743-750
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• 2017

It is important to ensure a uniform temperature distribution in greenhouses for the mushroom cultivation. The air temperature of the mushroom cultivation greenhouse is made uniform by supplying a constant air temperature with the underground air. The mushroom cultivation array in a greenhouse in seven columns and four rows can make smooth air flows between the rows and prevent air differences between the top and bottom. The buoyancy effect in the entering air of 0.5m/s based on following density difference depending on initial internal temperature needs to be considered. The locations of the Fan Coil Unit (FCU) and fan were defined through flow analysis in a greenhouse to distribute the optimal uniform temperature. In this study, the air conditioning system of a greenhouse with a sandwich heat insulting panel shape which is composed of a FCU and fan was designed by flow analysis. A relatively uniform temperature distribution can be formed because the circulation path of air becomes longer in the different locations of the FCU (inlet) and fan (outlet) through the internal temperature and flow analysis. The cultivation and quality uniformity of the mushrooms could be promoted through these environmental improvements.

• Journal of the Korean Wood Science and Technology
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• v.44 no.6
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• pp.821-827
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• 2016

This study evaluates the economic feasibility of industrializing fluidized bed dryer for wood particles. The theoretically required heat energy and energy efficiency were evaluated using a pilot scale fluidized bed dryer. When Mongolian Oak wood particles with 50% initial moisture content were dried in the fluidized bed dryer with air of $70^{\circ}C$ air circulating at 1.1-1.3 m/s for 30 minutes, the total theoretically required heat energy was 2,177 kJ. Of this, 1,763 kJ (approximately 81.0%) was used to heat the air flowing in from outside the dryer and 386 kJ (approximately 17.7%) was used to heat and remove water from the wood particles. Actual energy consumed was 7,560 kJ, giving energy efficiency of 28.8%. Thus, to industrialize a drying method such as fluidized bed drying, where the dryer volume is significantly larger than the volume of wood particles, it is necessary to minimize energy loss and maximize energy efficiency by designing the dryer size considering the amount of wood particles and choosing a suitable air circulation rate.

• Journal of Environmental Science International
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• v.17 no.7
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• pp.743-753
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• 2008

Gwangyang Bay is often severely confronted by photochemical pollutants due to its location and dense emissions. It is located in a basin on the south coast of the Korean peninsula and is crossed by a remarkable cluster of hills and mountains of a small horizontal scale that forms a channel. Clearly, the air flow field has a great influence on the dispersion of air pollutants. The characteristics of the wind flow patterns have an important effect on the dispersion of pollutants emitted. In these situations, the distribution of the ozone concentration is extremely complicated because of the superposition of circulations of the air flow fields, especially in complex coastal region. In this study, we examined the distribution of the high level ozone on Gwangyang Bay particularly during the episode day (for 5 years). Among these days, A high level ozone was induced by the development of a sea/land breeze local circulation system, as well as by an anabatic/catabatic flow from the mountains and valley with weakening of the synoptic wind. High level ozone distribution pattern(6 types) on Gwangyang bay is analyzed and the comparison of each pattern reveals substantial localized differences in intensity and distribution of ozone concentration from the site coherence and UPA analysis of ozone concentration. The observed VOC concentration had much difference in concentrations and daily variations between Jungdong and Samil.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.731-736
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• 2008

There was in a building and with the technical advance for a energy saving the secret efficiency of the building improved together and continuously was come. The indoor air environment brought about the deterioration which is remarkable because of it. But time of most the indoor air environmental matter is one in the element which healthily affects biggest in the moderns who lives from the interior space. Today the plan for the air environmental maintenance which dwelling space is appropriate is demanded, is the actual condition where the method of the ventilation control which is energy saving and efficient is necessary. From the research which it sees, number of ventilation 0.7 time of the aeration which is a domestic legal baseline is excessive is judged from the research which sees, The sleep hour assumes it stays most long the hour when, number of ventilation 0 time 0.1 times 0.4 times $CO_2$ consistency measurements and analyzes number of ventilation conclusive escape. And $CO_2$ peak point control leads it decides a data, effective and it talks an energy saving circulation control method and it does to sleep.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.8 no.4
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• pp.519-526
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• 1996

A 2D-LDV system was employed to investigate the flow field characteristics in fully developed drag reducing turbulent channel flows. The additive used in this study was Habon-G which showed splendid drag reduction effect and minimum mechanical degradation trend in the closed flow circulation loop. In order to have better understanding of the drag reduction mechanism, the instantaneous velocities were carefully measured under various experimental conditions and the flow characteristics including time-averaged velocity, turbulent intensity and Reynolds shear stresses were carefully assessed. The time-averaged velocity profiles of surfactant flows showed more parabolic shape(typically shown in a laminar flow) together with significant suppression of turbulent production, yielding the shear induced micelle structure orienting in the flow direction due to its isotropic characteristics. Especially it was observed that the maximum intensity for drag reducing flows was shifted away from the wall and that the streamwise and normal turbulent intensities were strongly altered. This phenomenon strongly suggests that the viscous sublayer becomes thicker with addition of surfactant. Turbulent momentum transport was drastically suppressed across the whole drag reducing channel flow.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.5
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• pp.452-458
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• 2004

The major cause of compressor failure is the decrease of oil viscosity due to floodback. In most previous researches on the compressor reliability, the relationship between oil circulation rate and performance or oil viscosity has been studied. Another research topic is flow visualization by using a sight glass on the bottom of a compressor sump area and accumulator. Both oil film thickness and oil level through the sight glass should be assessed for compressor reliability if the oil content of the mixture is small and low viscosity raise poor lubrication of pump bearing. In this study, the compressor reliability was assessed by measuring the viscosity of the mixture and calculating oil film thickness. The analysis of the relationship between bottom shell super heat and oil film thickness at heating operation was peformed. It is concluded that bottom shell superheat does not perfectly stand for the mixture's behavior for a low ambient heating operation and oil film thickness can give more detailed and direct criteria for compressor reliability.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.12
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• pp.852-858
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• 2010

In an absorption chiller, solution is circulated by a solution pump with an inverter to vary flow rate depending on operating conditions. For optimal operation, the solution level in the high temperature generator should be kept constant. However, a sensor for measuring continuous level is not available because of varying solution concentration. Instead, level switches are used and hence feedforward control associated with limit checking is a common practice. In the study, inverter frequencies are estimated from a dynamic simulation model and pump performance. Designed frequencies are compared with those implemented in real chillers. It was found that the frequencies used in real chillers are larger than those needed in circulation flow rates. It was intended to prevent system shut-off caused by dry-out. However, it is necessary to minimize the excessive frequency setting in order to reduce frequent pump stops and the range of solution level for continuous pump operation.