• 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
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• 제24권2호
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• pp.37-44
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• 2018

Purpose: This study investigates the influences of coughing direction and healthcare worker's location on the transport characteristics of coughed particles in airborne infection isolation room (AIIR), which is commonly called negative pressure isolation room, with a downward ventilation system. Methods: Computational Fluid Dynamics (CFD) was used to simulate the airflow and for tracing the behavior of particles. Results: The results show that the airflow pattern and coughing direction have a significant influence on the characteristics of particle dispersion and deposition. When healthcare workers are in the isolation room with the patient who is lying on the bed, it is recommended to be located far from the anteroom to reduce the exposures from infectious particles. And when the patient is lying, it is more effective in removing particles than when the patient is in Fowler's position. Although it is an isolation room that produces unidirectional flow, coughing particles can spread to the whole room and a large number of particles can be deposited onto patient, bed, side rails, healthcare worker, ceiling, floor, and sidewall. Implications: Following the patients' discharge or transfer, terminal cleaning of the vacated room, furniture, and all clinical equipment is essential. Also, it is necessary to establish detailed standard operating procedure (SOP) in order to reduce the risk of cross-contamination.

• 한국생산제조학회지
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• 제20권2호
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• pp.180-186
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• 2011

This paper describes a micro electrical discharge machining (MEDM) technique that uses an insulated tool in combination with ultrasonic vibration to drill micro holes. As the machining depth becomes deeper, the dispersion of debris and circulation of the dielectric fluid are difficult to occur. Consequently, machining becomes unstable in the machining region and unnecessary electrochemical dissolution and secondary discharge sparking occur at the tool side face. To reduce the amount of unnecessary side machining, an insulated tool was used. Ultrasonic vibration was applied to the MEDM work fluid to better remove debris. Through these methods, a $1000\;{\mu}m$ thick stainless steel plate was machined by using a $73\;{\mu}m$ diameter electrode. The diameters of the hole entrance and exit were $96\;{\mu}m$ and $88\;{\mu}m$, respectively. It took only 351s to completely drill one hole.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 유기절연재료 방전 플라즈마연구회
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• pp.108-111
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• 2003

The main objective of this paper is to module design and pressure relief test a new type of polymer gapless surge arrester for power distribution line. Metal oxide surge arrester for most electric power system applications, power distribution line and electric train are now being used extensively to protect overvoltage due to lightning. Surge arresters with porcelain housing must not have explosive breakage of the housing to minimize damage to other equipment when subjected to internal high short circuit current. When breakdown of gapless elements in a surge arrester occurs due to flashover, fault short current flows through the arrester and internal pressure of the arrester rises. The pressure rise can usually be limited by fitting a pressure relief diaphragm and transferring the arc from the inside to the outside of the housing. However, there is possibility of porcelain fragmentation caused by the thermal shock, pressure rise, etc. Non-fragmenting of the housing is the most desired way to prevent damage to other equipment. The pressure change which is occurred by flashover become discharge energy. This discharge energy raises to damage arrester housing and arrester housing is dispersed as small fragment. Therefore, the pressure relief design is requested to obstruct housing dispersion.

• 대한토목학회논문집
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• 제6권2호
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• pp.93-101
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• 1986

정지수역(靜止水域)에서 연직상향(鉛直上向)으로 방류(放流)되는 평면부력(平面浮力)?의 거동을 연속방정식(連續方程式), 운동량수송식(運動量輸送式) 및 추적물(追跡物) 수송식(輸送式)에 의하여 수치적(數値的)으로 해석한다. 이 해석은 유함수(流凾數)와 과수송식(過輸送式)을 도입하고 Prandtl 난류모형(亂流模型)을 이용하였다. 방류밀도(放流密度) Froude 수(數)가 4~32인인 부력(浮力)?의 발달된 흐름영역(領域)에서 구한 ?중심선의 속도(速度)와 온도변화(溫度變化), ?주변수역(周邊水域)의 온도분포(溫度分布)와 흐름양상은 기존자료와 잘 맞음을 확인할 수 있다. 적분형해석(積分型解析)에 필요한 퍼짐율과 확산비(擴散比)가 방류밀도(放流密度) Froude 수(數)와 방류구(放流口)로부터의 거리의 함수로 유도된다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 춘계학술대회 논문집
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• pp.175-179
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• 2005

The main objective of this paper is to module design and pressure relief test a new type of polymer gapless surge arrester for power distribution line. Metal oxide surge arrester for most electric power system applications, power distribution line and electric train are now being used extensively to protect overvoltage due to lightning. Surge arresters with porcelain housing must not have explosive breakage of the housing to minimize damage to other equipment when subjected to internal high short circuit current. When breakdown of gapless elements in a surge arrester occurs due to flashover, fault short current flows through the arrester and internal pressure of the arrester rises. The pressure rise can usually be limited by fitting a pressure relief diaphragm and transferring the arc from the inside to the outside of the housing. However, there is possibility of porcelain fragmentation caused by the thermal shock, pressure rise, etc. Non-fragmenting of the housing is the most desired way to prevent damage to other equipment. The pressure change which is occurred by flashover become discharge energy. This discharge energy raises to damage arrester housing and arrester housing is dispersed as small fragment. Therefore, the pressure relief design is requested to obstruct housing dispersion.

• 상하수도학회지
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• 제25권5호
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• pp.667-679
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• 2011

In this study, the influences of pollutant from Dae-po Stream and So-gam Stream located at the downstream of Nak-dong River on the water quality at Mul-geum water intake station were analyzed using RAMS model. Field measurements of velocity by ADCP, and water quality distribution of BOD and TP by water sampling were carried out to present the input and verification data for numerical simulations. The comparison between RAM2 and ADCP measurement, which aimed for the analysis of 2-D velocity distribution around Mul-geum water intake station showed that two results matched well along the spanwise direction. The prediction of pollutant concentration by RAM4 agreed fairly well with the measured data except for the points nearby right banks in the vicinity of tributary pollutant source. Flushing effect by the increase of mainstream discharge in Nak-dong River was analyzed to provide the damage mitigation in preparation for the accidental water pollution. With increasing mainstream discharge, high velocity and increased water quantity induced increasing dilution effect, thereby decreasing the inflow pollutant concentration rapidly.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전기물성,응용부문
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• pp.220-222
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• 2005

We can classify two cases in a way to observe an atom of gas state or a molecule using the laser. First case is way to use dispersion phenomenon like Rayleigh scattering, Thomson scattering, Mie scattering, Raman Scattering. And Second case is a way to use change phenomenon like a LAS (Laser Absorption Spectroscopy), LIF (Laser Induced Fluorescent). In this paper, we have measured the meta-stable density and the distribution by using a LAS method in Xe discharge lamp. The laser absorption spectroscopy (LAS) is useful to investigate the behavior of such species. The xenon atoms in the $1S_4$ and $1S_5$ generate excited $Xe^*$(147nm) and $Xe_{2}^*$(173nm) dimers in Xe plasma. It is found that the intensity of VUV 147nm emission is proportional to that of the IR 828nm emission, and the VUV 173nm emission is roughly proportional to that of the IR 823nm emission. The laser is used CW laser that consist of AlGaAs semiconductor and energy level is used 823.16nm wavelength. We measured signal of monochrometer from the lamp center while will change a discharge electric current by 6mA in 3mA and calculated meta-stable state density of a xenon atom through a measured value.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2004년도 춘계학술대회
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• pp.247-257
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• 2004

Electrodes were fabricated based on activated carbon powder BP-20, conducting agent such as Super P, vapor grown carbon fiber (VGCF) and acetylene black (AB), and the mixed binders of flexible poly(vinylidenefluoridehexafluoropropylene) [P(VdF-co-HFP)] and cross linking dispersion agent of polyvinylpyrrolidone (PVP) to increase mechanical strength. According to impedance measurement of the electrode with the addition of conducting agent, we found that it was possible to charge rapidly by the fast steady-state current convergence due to low equivalent series resistance (AC-ESR, fast charge transfer rate at interface between electrode and electrolyte and low RC time constant. The self-discharge of unit cell showed that diffusion process was controlled by the ion concentration difference of initial electrolyte due to the characteristics of Electric Double Layer Capacitor (EDLC) charged by ion adsorption in the beginning, but this by current leakage through the double-layer at the electrode/electrolyte interface had a minor effect and voltages of curves were remained constant regardless of electrode material. We found that the 2.3V/230F grade EDLC would be applied to industrial safety usage such as uninterrupted power supply (UPS) because of the constant DC-ESR by IR drop regardless of discharge current.

• 한국안전학회지
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• 제31권3호
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• pp.156-161
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• 2016

An accident of an ammonia tank pipeline at a storage plant resulted in one death and three injuries in 2014. Many accidents including toxic gas releases and explosions occur in the freezing and refrigerating systems using ammonia. Especially, the consequence can be substantial due to that the large amount of ammonia is usually being used in the refrigeration systems. In this study, offsite consequence analysis has been investigated when ammonia leaks outdoors from large storages. Both flammable and toxic effects are under consideration to calculate the affected area using simulation programs for consequence analysis. ERPG-2 concentration (150 ppm) has been selected to calculate the evacuation distance out of various release scenarios for their dispersions in day or night. For offsite residential, the impact area by flammability is much smaller than that by toxicity. The methodology consists of two steps as followings; 1. Calculation for discharge rates of accidental release scenarios. 2. Dispersion simulation using the discharge rate for different conditions. This proactive prediction for accidental releases of ammonia would help emergency teams act as quick as they can.

• Bulletin of the Korean Chemical Society
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• 제30권8호
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• pp.1733-1737
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• 2009

A new cathode material based on Li$Ni_{0.8}Co_{0.15}Al_{0.05}O_2$ (LNCA)/polyaniline (Pani) composite was prepared by in situ self-stabilized dispersion polymerization in the presence of LNCA. The materials were characterized by fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-Vis), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Electrochemical properties including galvanostatic charge-discharge ability, cyclic voltammetry (CV), capacity, cycling performance, and AC impedance were measured. The synthesized LNCA/Pani had a similar particle size to LNCA and exhibited good electrochemical properties at a high C rate. Pani (the emeraldine salt form) interacts with metal-oxide particles to generate good connectivity. This material shows good reversibility for Li insertion in discharge cycles when used as the electrode of lithium ion batteries. Therefore, the Pani coating is beneficial for stabilizing the structure and reducing the resistance of the LNCA. In particular, the LNCA/Pani material has advantageous electrochemical properties.