• Journal of the Korean Society of Visualization
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• v.14 no.1
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• pp.19-26
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• 2016

Modern people spend much time at indoor space. So, People want to make better indoor air condition. But the facade of building is made of glass to be seen urbanely, the effect of solar radiation makes indoor environment worse. This study designs an open space affected by solar radiation with 4-way cassette air-conditioner. Using numerical simulation, this paper investigates thermal comfort and ventilation performance with discharge angles $30^{\circ}$ and $45^{\circ}$. To study thermal comfort, this paper studies distribution of velocity, temperature and effective draft temperature. Also, this paper introduces concept of air age to study ventilation performance. The flow influenced by solar radiation determines thermal comfort and ventilation performance in room space. This study shows that discharge angle of 45 degree has better thermal comfort and ventilation performance than that of 30 degree.

• Journal of computational fluids engineering
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• v.2 no.1
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• pp.93-108
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• 1997

This paper describes several computational results on the various energy and environmental problems using Patankar's SIMPLE method. The specific problems included in this study are : pollutant and flammable material dispersions in open and confined areas, buoyancy-driven flow in a lake, primary clarifier for water and waste water treatment, hood ventilation in workplace. cyclone combustor and Dow chlorination reactor. A control-volume based finite-difference method is employed together with the power-law scheme. The pressure-velocity coupling is resolved by the use of the revised version of SIMPLE, says SIMPLER and SIMPLEC. The Reynolds stresses are closed using the standard or RNG κ-ε models. A nonequilibrium turbulent reaction model is developed for the application of the chlorination process in the Dow thermal reactor. Other important empirical models and physical insights appeared in this study are presented and discussed in a brief note. The computational method developed in this study is considered, in general, as a viable tool for the design and determination of the optimal operating condition of various environmental engineering system of interest.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.2
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• pp.205-215
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• 2001

An experimental study has been performed to investigate the heat transfer characteristics of fin and tube heat exchanger. The existing transient and steady methods are very difficult to apply for the measurements of heat transfer coefficients of a thin heat transfer model. In this study the lumped capacitance method was adopted. The heat transfer coefficients were measured by using the lumped capacitance method based on the liquid crystal thermography. The method is validated through impinging jet and flat plate flow experiments. The two experiments showed that the results of the lumped capacitance method with polycarbonate model showed very good agreements with those of the transient method with acryl model. The lumped capacitance method showed similar results regardless of the thickness of polycarbonate model. The method was also applied for the heat transfer coefficient measurements of a fin and tube heat exchanger. The quantitative heat transfer coefficients of the plate fin were successfully obtained. As the frontal velocity increased, the heat transfer coefficients were increased, but the color-band shape showed similar patterns regardless of frontal velocity.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.11
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• pp.939-947
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• 2002

Local and overall heat transfer characteristics of fin-flat tube heat exchangers with and without vortex generators are investigated. Local heat transfer coefficients are measured with the heat exchanger model using naphthalene sublimation technique. In case of a fin-flat tube heat exchanger without vortex generators, only the horseshoe vortices formed around tubes augment the heat transfer. On the other hand, longitudinal vortices created artificially by vortex generators enhance heat transfer dramatically in case of a fin-flat tube heat exchanger with vortex generators. Overall heat transfer coefficients are measured with the prototype of the fin-flat tube heat exchanger with and without vortex generators in a wind tunnel and results are compared with those of a fin-circular tube heat exchanger with wavy fin. Friction losses for heat exchangers are also measured and compared. The fin-flat tube heat exchanger with vortex generators is found to be more effective than the fin-circular tube heat exchanger with wavy fin.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.8 no.1
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• pp.120-139
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• 1996

Experiment was performed to study the heat transfer characteristics in 27 kinds of 15 : 1 scale models of multi-louverred fin heat exchangers with a wide range of variables(R $e_{Lp}$ =100~1, 800, $L_p$/F$p$=0.3~0.9, $\theta$=20$^{\circ}$~40$^{\circ}$). Thermofoil heaters were used to heat the louver fins and the local average Nusselt number for each louver in the louver array was obtained at constant wall temperature conditions. Correlations are developed to predict the heat transfer characteristics and drag coefficients. Generally, the heat transfer characteristics in the multi-louvered fins is shown to be similar to those of the laminar heat transfer on a flat plate. As the Reynolds number, the louver pitch to fin pitch ratio$L_p$/F$p$and the louver angle($\theta$) increase respectively, the average Nusselt number increases, but the variation of average Nusselt number as a function of the louver angle is smaller than that as a function of the louver pitch to fin pitch ratio. In case of$L_p$/F$p$ <0.5, the average Nusselt number of the 3rd louver is especially lower than the others, it is expected that it is due to the flow structure such as a recirculation flow and a flow separation.

• Tuberculosis and Respiratory Diseases
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• v.49 no.4
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• pp.466-473
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• 2000

Background : Patients with locally advanced non-small cell lung cancer are often treated with radiation alone or in combination with chemotherapy. Both modalities have a potentially damaging effect on pulmonary function. In order to examine changes in the cardiopulmonary exercise function of patients with locally advanced non-small cell lung cancer before and after conventional radiotherapy, we conducted a prospective study involving patients with such cancer, that had received radiation therapy. Method : Resting pulmonary function test, thoracic radiographic finding and cardiopulmonary exercise test(CPET) were assessed prior to and 4 weeks following radiation therapy in 11 male patients with locally advanced non-small cell lung cancer. Patient with endobronchial mass were excluded. Results : The forces vital capacity (FVC), forced expiratory volume in 1 second ($FEV_1$ and maximal voluntary ventilation (MVV) did not decreased between before and 4 weeks after radiation but the diffusing capacity (DLCO) had decreased by 11% 4 weeks after radiation, which was not statistically significant. No changes in maximal oxygen consumption ($VO_2$max), carbon dioxide production ($VCO_2$), exercise time and work load were attributed to radiation therapy. Follow up cardiopulmonary exercise testing revealed unchanged cardiovascular function, ventilatory function and gas exchange. No difference in cardiopulmonary exercise test performance was observed between pre- and post-radiation. Conclusion : Cardiopulmonary exercise function did not decrease within the short-term after the radiation of patients with locally advanced non-small cell lung cancer.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.10
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• pp.659-665
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• 2017

When an electrically conducting fluid flows through a staggered tube bank, the heat transfer and fluid flow features are changed by the externally introduced magnetic field. This study provides a numerical investigation of this phenomenon. Heat and fluid flows are investigated for unsteady laminar flows at Reynolds numbers of 50 and 100 with the Hartmann number gradually increasing from zero to 100. As the Hartmann number increases, and owing to the effects of the introduced magnetic field, the velocity boundary layer near the tube wall is thinned, the flow separation is delayed downstream, and the shrinkage of a recirculation zone formed near the rear side is observed. Based on these thermo-fluid deformations, the resulting changes in the local and average Nusselt number are investigated.

• Journal of The Korean Dental Society of Anesthesiology
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• v.2 no.2 s.3
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• pp.107-113
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• 2002

Hyperventilation is defined as ventilation in excess of that required to maintain normal blood $PaO_2$ and $PaCO_2$. It is produced by several distinct causes: anxiety, respiratory alkalosis, increased blood catecholamine levels, and a decrease in the level of the ionized calcium in the blood. The dental fears about acute pain, needle, drill and dental surgery lead to the severe anxiety and increased blood catecholamine level. Therefore, the most dental patient should be cared gently as the stress reduction protocol. In spite of the gentle care, two cases of hyperventilation were occurred during local anesthesia for incision and drainage of acute odontogenic infectious lesions. We suggest that the dental patients with acute odontogenic infection must be attention for the manifestation of hyperventilation, especially in the medically compromised conditions.

• Research in Community and Public Health Nursing
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• v.13 no.3
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• pp.574-583
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• 2002

'채석(quarrying)'산업은 노천광산에서 광물을 캐내는 작업을 모두 포함하는 광범위한 산업을 의미한다. 1900년대에 들어오면서 채석작업에 홈연소기(channel burner)을 이용한 불꽃절개법(flame cutting)이 이용하여 근로자의 먼지 노출이 많이 감소하였다. 채석작업으로 인한 주 된 건강문제는 먼지, 소음, 진동 노출이며, 노천작업장으로 작업환경이 개방되어 있어 환경측정 및 관리가 불가능하므로 개별근로자의 먼지와 소음 노출 측정 및 예방이 중요하다. 본 연구는 미국의 일개 채석회사의 근로자 건강관리사업을 평가하였다. 연구자료는 저자가 현장 방문을 통하여 구한 자료와 연구대상 회사의 안전관리자의 의견 및 미국 산업안전보건국 전산자료를 이용하였다. 채석사업장에서 이루어지는 작업은 크게 채석작업과 실내에서 이루어지는 가공작업 및 운반과 보관이며, 미국 산업안전보건국(OSHA)의 표준산업분류(SIC)에서 1411(채석업)과 3281(채석가공업)에 해당한다<표 1>. 연구 대상 사업장에서 이루어지는 산업보건프로그램은 먼지 노출 예방을 위해 석재 채취시 물분사법(water jet quarrying)과 국소환기법을 사용하고 소음 노출 예방을 위해 귀마개를 사용하며 사고 예방을 위하여 안전모와 철모, 보안경, 안전조끼, 보호장갑, 안전끈(harness)을 착용하였다. 평가 결과로 나온 연구 대상 사업장에서 적용하여야 할 산업보건 프로그램은 첫째, 먼지 노출로 인한 건강문제를 예방하기 위하여 근로자 개별 노출 측정을 하고, 둘째 실내가공작업장의 근로자를 대상으로 한 먼지와 소음 노출 측정 및 환경측정이 필요하며, 셋째 안전관리를 위해 채석장에 안전표지판을 설치하여야 하며, 실내가공 작업장의 자동이동시스템을 작업별로 채색하여 식별을 용이하게 하여야 하겠다. 또한 이 연구 결과를 영세사업장의 산업간호프로그램인 'Clean 3D'사업에서 적용하여 우리나라 채석사업장 근로자 건강관리를 발전시켜야 하겠다.

• Clinical and Experimental Pediatrics
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• v.46 no.8
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• pp.784-788
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• 2003

Purpose : Perinatal asphyxia occurring in newborn is one of the major causes of acute mortality and chronic neurological disability in survivors. We have studied the relationship between early electroencephalography(EEG) findings and clinical course and neurologic outcome in severe asphyxiated neonates. Methods : Between the period of July 1999 and June 2002, 25 neonates who were diagnosed with severe perinatal asphyxia(1-minute Apgar score of ${\leq}3$ and initial pH is less than 7.2) at NICU in Dongsan Medical Center were enrolled. An EEG was recorded and analyzed within three days of life and divided into two groups - group 1(normal or focal change on EEG) and group 2(generalized abnormal EEG). Between the two groups, clinical courses and neurologic outcomes were compared. Results : Fifteen infants(60%) were group 1 and ten infants(40%) were group 2(polyspikes, burst-suppression, generalized low voltage). Associated maternal disease, days of hospitalization, need for ventilator support, delay of oral feeding and convulsion duration are significantly higher and longer in group 2. Also, poor neurologic outcome(expire, developmental delay) was significantly higher in group 2(60%) than group 1(13.3%). Conclusion : Thus, the early neonatal EEG in asphyxiated newborn can be a predictable diagnostic tool in assessment of neurologic outcome.