• International Journal of Air-Conditioning and Refrigeration
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• 제16권3호
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• pp.89-99
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• 2008

Indoor ozone has received attention because of its well-documented adverse effects on health. In addition to the inherently harmful effects of ozone, it can also initiate a series of reactions that generate potentially irritating oxidation products, including free radicals, aldehydes, organic acids and secondary organic aerosols (SOA). Especially, ozone reacts actively with terpene. The overarching goal of this work was to better understand ozone and terpene distributions within rooms. Towards this end, the paper has two parts. The first describes the development of a cylindrical test chamber that can be used to obtain the second order rate constant $(k_b)$ for the bi-molecular chemical reaction of ozone and terpene in the air phase. The second consists of model room experiments coupled with Computational Fluid Dynamics (CFD) analysis of the experimental scenarios to obtain ozone and terpene distributions in various turbulent flow fields. The results of CFD predictions were in reasonable agreement with the experimental measurements.

• Journal of Advanced Marine Engineering and Technology
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• 제35권3호
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• pp.335-340
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• 2011

Building energy saving is one of the most important issues in these days. Control algorithm for energy saving should be designed properly to reduce power consumption in building. Recently, building energy system consists of hybrid energy system coupling with RE (Renewable Energy) source. In this paper, an optimum control algorithm for building energy saving is applied to BEMS (Building Energy Management System) by using an outdoor air temperature prediction strategy. BEMS coupling with renewable energy can control HVAC (Heating, Ventilating and Air-Conditioning) system effectively. In order to verify the effectiveness of building energy saving, BEMS was tested for several months at a laboratorial chamber with an air conditioner, fan and heater. To this end BEMS embedded control algorithm has been tested successfully.

• 한국농공학회지
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• 제36권4호
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• pp.87-94
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• 1994

The aim of the work descrihed in this paper is to study a characteristics of an unsaturated soil for the different matric suctions. To this end, a series of suction controlled isotropic and triaxial compression tests is conducted on silty sands. Matric suction is controlled by the axis translation technique using high air entry ceramic disk. Total volume change, air and water volume changes are measured by the device made for the experiment. The specimens are compacted using a half of Proctor compaction energy and with the water contents of 5% drier than the optimum moisture contents. Isotropic compression and triaxial compression tests are conducted on the specimen at each equilibrium state of matric suction. From test results, volume changes and deviator stresses are analyzed at each state and their relationships are formulated.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2007년도 제34회 KOSCO SYMPOSIUM 논문집
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• pp.63-68
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• 2007

An experimental study was carried out to investigate gasification process of wood sawdust in the 1-dimensional downdraft fixed bed gasifier. The preheated air which was used oxidizer and steam were used as a gasifying agent. The downdraft fixed bed gasifier obtains more amount of hydrogen and methane by increasing residence time of supplied air. The operating parameters, the supplied air temperature and steam were used. The oxidizer temperature was varied from 500K to 620K and vapor was added. The gasification process was monitored by measuring temperature at three position near the biomass using R-type thermocouples and the syngas composition was analyzed by gas chromatograph. We get the sample gas at the end of gasifier and it was eonugh time to finishing the chemical reaction. Finally, the amount of hydrogen and methane were increased widely as increasing the oxidizer temperature and adding steam.

• 대한기관식도과학회지
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• 제14권1호
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• pp.5-7
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• 2008

Subcutaneous cervicofacial, mediastinal emphysemas are complications associated with head and neck surgery, trauma, infectious processes, tooth extraction. Drill cooling stream and dental syringe air ject are the sources of high pressure air that may enter exposed soft tissue. Since the introduction of the high-speed air turbine drill in the 1960s, The incidence of iatrogenic subcutaneous emphysema has increased. Most cases begin to resolve after 2 to 3 days and residual swelling is usually minimal at the end of 7 to 10 days. Surgical approach is not advised because it is likely to be ineffective. The differential diagnosis of neck swelling after dental procedure includes hematoma, cellulitis, angioedema, allergic reaction, subcutaneous emphysema. We report a rare case of patient with subcutaneous cervicofacial emphysema and mediastinal emphysema secondary to third molar extraction.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 춘계학술대회 논문집
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• pp.384-389
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• 2009

In the present paper, dynamic characteristics and vibration control performance of a cylindrical shell structure are experimentally investigated and results are presented in the air and underwater conditions. End-capped cylindrical shell structure is manufactured and Macro-Fiber Composite (MFC) actuators are attached on the inside-surface of the structure. Modal characteristics are studied in the air and under the water conditions and then equation of motion of the structure is derived from the test results. Structural vibration control performances of the proposed structure are evaluated via experiments with optimal control algorithm. Vibration control performances are presented both in the frequency and time domains.

• 한국소음진동공학회논문집
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• 제19권9호
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• pp.899-906
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• 2009

In the present paper, dynamic characteristics and vibration control performance of a cylindrical shell structure are experimentally investigated and results are presented in the air and underwater conditions. End-capped cylindrical shell structure is manufactured and macro-fiber composite(MFC) actuators are attached on the inside-surface of the structure. Modal characteristics are studied in the air and under the water conditions and then equation of motion of the structure is derived from the test results. Structural vibration control performances of the proposed structure are evaluated via experiments with optimal control algorithm. Vibration control performances are presented both in the frequency and time domains.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.611-618
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• 2000

The test facility of the 1/60-scale models for the train-tunnel interactions was recently developed to investigate the effects of entry portal shapes, hood shapes and air-shafts for reducing the micro-pressure waves radiating to the surroundings of the tunnel exits by KRRI in Korea. The launching system of train model was chosen as air-gun type. In present test rig, after train model is launched, the blast wave by the driver did not enter to inside of the tunnel model. The train model is guided on the one-wire system from air-gun driver to the brake parts of test facility end. Some cases of the experiments were compared with numerical simulations to prove the test facility.

• 한국자동차공학회논문집
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• 제9권4호
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• pp.10-17
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• 2001

The performance of a radiator is generally determined using a wind tunnel, in which the air velocity is uniform. However, when it is installed in a car, the distribution of the air velocity becomes nonuniform due to front-end openings, cross members, and horns etc., resulting in lower performance. In this study, several underhood flow simulations have been first performed to get flow rates and velocity distributions over the radiator. Secondly heat release rates are calculated by both a performance curve and a radiator model. Finally, using an engine cooling system simulator, radiator-top-tank temperature is predicted and the variations of heat release rate and radiator-top-tank temperature with nonuniformity of air velocity distributions are analyzed. The results show that the current engine cooling model successfully accounts for the nonuniformity effects that should be considered for higher accuracy in predicting engine cooling performance.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2005년도 동계학술발표대회 논문집
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• pp.229-234
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• 2005

This study aims to build basic data for a optimization of a ventilation system for indoor environment improvement in school building. To this end, we conducted field tests and computation fluid dynamics simulations about a indoor environment in dependence on operation of a ceiling type inverter air conditioner and ventilation system. The results could be summarized as follows. (1) For the ventilation system of 350CMH, 500CMH and 850CMH, reduction of each $CO_2$ concentration was measured 662ppm, 748ppm and 526ppm. (2) A optimal discharge angle of the ceiling type inverter air conditioner system was evaluated 45 degree in heating and cooling.