• 청정기술
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• 제20권2호
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• pp.171-178
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• 2014

이 연구에서는 대형 주물공정 용접작업장 근로자들의 건강보호 및 작업환경 개선을 위해 위해인자 조사 및 분석작업을 수행하였다. 또한, 대상 작업장의 작업환경을 개선하기 위해 측정 및 전산유체해석 모델링을 수행한 후 효과적인 환기방법을 제안하였다. 대형 주물공정 용접작업장 근로자들의 건강 위해인자를 조사한 결과, A사는 산화철분진, B사와 C사는 용접흄, D사는 용접 흄과 산화철분진이 주오염원인 것으로 확인되었다. 작업자 호흡영역에서의 흄 농도는 $0.05{\sim}4.37mg/m^3$이었고, 용접작업장 공기 중 흄 농도는 $0.13{\sim}7.54mg/m^3$이었다. 또한, 용접작업 시 최적의 환기방법을 제안하기 위해 측정 및 전산유체해석 모사를 수행한 결과, 배기공정의 경우에는 배기 덕트를 용접점에 근접시켜 국소배기를 실시하는 것이 효과적인 것으로 나타났다. 급기공정의 경우에는 개구부 끝 부분에서 급기를 하며 급기용 팬은 작업 공간 외부에 설치하는 것이 효과적일 것으로 나타났다. 향후 대형 주물공정 용접작업장의 터널형 반밀폐 공간에 대한 환기방법을 표준화한다면 주물산업 및 조선업 등에 종사하는 용접 근로자들의 건강보호 및 작업환경 개선에 매우 효과적일 것으로 판단된다.

• The Korean Journal of Physiology and Pharmacology
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• 제3권2호
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• pp.183-189
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• 1999

This investigation is to determine whether the surface complexation of iron influence acute pulmonary responses induced by silica. For this study, three varieties of cation complexed silica were used: $silica-H^+,\;-Zn^{2+},\;and\;-Fe^{3+},$ since the first two are not active in the transport of electrons and generate little free radicals relative to the dust with the surface iron. Rats (270 to 280 g) were intratracheally (IT) instilled with saline, $silica-H^+,\;-Zn^{2+},\;or\;-Fe^{3+}$(5 mg in 0.5 ml saline). After 4 h, cell number, type, and differentiation were analysed in the bronchoalveolar lavage cells, and the levels of lactate dehydrogenase (LDH) and total protein were determined in the lavage fluid. In addition, bronchoalveolar lavage cells were cultured, and nitric oxide production was measured using nitrate assay. Inducible nitric oxide synthase (iNOS) mRNA in the bronchoalveolar lavage cells was also determined by northern blot analysis. Differential counts of the lavage cells showed that red blood cells were increased by 9-, 8-, and 13-fold and total leukocytes (lymphocytes plus polymorphonuclear neutrophils) by 48-, 36-, and 33-fold, following IT $silica-H^+,\;-Zn^{2+},\;and\;-Fe^{3+},$ respectively compared with the saline group. Meanwhile, there were no significant differences in red blood cells and total leukocytes among any of the cation complexed silica groups. The levels of LDH and total protein in the lavage fluid were significantly increased by 3- to 4-fold. However, compared among these silica groups, $Fe^{3+}$? complexation did not significantly change the LDH activity and total protein. NO production in cultured bronchoalveolar lavage cells was elevated by 2-fold, following IT any of the silica treatments compared with the saline group. Furthermore, the steady-state levels of iNOS mRNA in the lavage cells were greatly increased. There were any differences in iNOS mRNA expression among the silica-treated groups as with NO production. These findings suggest that surface complexed iron may not influence the acute pulmonary responses resulted from 4h exposure to silica.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2327-2332
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• 2007

This study investigates on the inhalation force improvements of hood consisted one of the local ventilation systems attached the new device named as gas-guidance-device for removed a pollution source. The numerical method applying finite element method is calculated the velocity and pressure distributions of a moving fluid at the beginning and the inside of a hood with and without the gas-guidance-device in hood. And, the experimental study is measured the wind velocity using the anemometer at the same condition of numerical study. Also, the optimum shape of gas-guidance-device which is suitable for hood shape derived from the numerical and experimental results. The results of this study is supplied the important data to an industrial field for control of a pollution source in the engineering aspect. Moreover, the introduced technique of hood attached the gas-guidance-device is very useful to remove the harmful materials such as dust and waste happened in the manufacturing factory.

• International Journal of Concrete Structures and Materials
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• 제7권3호
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• pp.193-202
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• 2013

Geopolymer mortar compressed blocks were prepared using fly ash, ground granulated blast furnace slag, silica fume and metakaolin as binders and sand/quarry dust/pond ash as fine aggregate. Alkaline solution was used to activate the source materials for synthesizing the geopolymer mortar. Fresh mortar was used to obtain the compressed blocks. The strength development with reference to different parameters was studied. The different parameters considered were fineness of fly ash, binder components, type of fine aggregate, molarity of alkaline solution, age of specimen, fluid-to-binder ratio, binder-to-aggregate ratio, degree of saturation, etc. The compressed blocks were tested for compression at different ages. It was observed that some of the blocks attained considerable strength within 24 h under ambient conditions. The cardinal aim was to analyze the experimental data generated to formulate a phenomenological model to arrive at the combinations of the ingredients to produce geopolymer blocks to meet the strength development desired at the specified age. The strength data was analyzed within the framework of generalized Abrams' law. It was interesting to note that the law was applicable to the analysis of strength development of partially saturated compressed blocks when the degree of saturation was maintained constant. The validity of phenomenological model was examined with an independent set of experimental data. The blocks can replace the traditional masonry blocks with many advantages.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.483-486
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• 2006

The fan is widely used to cool high heat flux generated as of the electronic communication device consoles. It, however, makes a lot of noises that interfere considerably with the operation environment. This study was conducted to obtain the cooling design technology of the consoles through being equipped with the Heat Pipe Heat Exchangers (HPHE) together with low revolution fans in place of existing fans for the cooling technology of the forced convection. Not only the sealed type consoles but the HPHE were also designed so as to cool effectively the heat generated from the inside of the console. The simulation was conducted by computational numerical analysis along with its experiments. The results of the numerical analysis and experiments were compared in order to improve the cooling technology of the consoles mounted with the HPHE. Consequently, instead of loud fan noise generated as of existing forced convection methods, the cooling technology of HPHE can remarkably improve many problems such as the operation environment, indoor dust, malfunction caused by pollution sources and so on.

• Journal of Advanced Marine Engineering and Technology
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• 제38권2호
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• pp.147-153
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• 2014

The centrifugal oil purifier is used in an engine for lubrication and to remove impurities. The momentum needed for the rotation of the cylindrical chamber is obtained by jet injections. An impure particle in the oil is separated by the centrifugal forces moving to the inner wall of the rotating cylindrical chamber body. The dust particles are eliminated when the particles are absorbed onto the surface of the inner wall of the chamber body. The flow characteristics and the physical behaviors of particles in this centrifugal oil purifier were investigated numerically and the filtration efficiencies was evaluated. For calculations, a commercial code is used and the SST (Shear Stress Transport) turbulence model has been adopted. The MFR (Multi Frames of Reference) method is introduced to consider the rotating effect of the flows. Under various variables, such as particle size, particle density and rotating speed, the filtration efficiencies are evaluated. It has been verified that the filtration efficiency is increased with the increments in the particle size, the particle density and the rotating speed of the cylindrical chamber.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.905-910
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• 2007

The cubicle of high speed train is the equipment where the important train- operating equipments are concentrated, so it requires the higher safety and reliability than any other equipment. Recently, the power car cubicle of KTX-II is, basically similar to that of KTX-I and HSR350x in its size, but consequently, as more sophisticated ATP/ATC and other parts are added, the order company points out the problem of rising temperature in summer. Especially, the interpretation about the possibility of guaranteeing the minimum freezing performance becomes necessary, when Fan Tray is out of order. This paper presents the method of improving the freezing performance while minimizing the effect of dust, and the method of guaranteeing the present freezing performance by the best arrangement of Fan Tray, when Fan Tray is out of order. And as a method of verifying this, we would like to predict the pressure, speed of a running fluid and temperature distribution of cubicle through the flow analysis.

• 대한기계학회논문집B
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• 제25권11호
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• pp.1616-1623
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• 2001

A basic experimental study has been carried out to find out the design parameters of fuel 2-staging atomizers in order to reduce nitrogen oxides(NOx) rate emitted from the steam boilers used the liquid fuel. The heavy fuel oil(B-Coil) and fuel 2-staging Y-jet twin-fluid atomizers were adopted in this study. The results of this paper were obtained from the real as well as the model scale atomizers. In the case of model atomizers test, NOx reduction rate was strongly dependent on the staged fuel rate, but it was weakly dependent on the injection hole arrangement and air swirl conditions. The real scale atomizers was designed and manufactured on the base of these test results, and those was mounted and operated in the real boiler generates 185 ton steam per an hour. The reduction rate of the model and real plant was reached 10∼30% of base NOx by atomizers. but dust was sharply increased in the low O$_2$combustion region of the real plant.

• 한국산업보건학회지
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• 제28권2호
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• pp.190-199
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• 2018

Objectives: The purpose of this case study is to assess the current airflow and find the ideal ventilation conditions in tank reactors for minimizing the possibility of exposure respiratory dusts(size of $2.5{\mu}m$, $10{\mu}m$) when workers exchange catalysts in the tank reactors. Methods: A Numerical study was performed to determine ideal ventilation conditions, We considered two sizes of airborne respiratory particles($2.5{\mu}m$, $10{\mu}m$) at 12points from the bottom of tank reactor. We changed input & output ventilation conditions and analyzed the particle motion in the tank reactor. The star-ccm+, computational fluid dynamics tool was used to predict air & particle flow patterns in the tank reactor and a numerical simulation was achieved by applying the realized ${\kappa}-{\varepsilon}$ turbulence model and the Lagrangian particle tracking method. Results: From the results, the increase of recirculation air had a significant impact on removing dusts because they are removed by HEPA filter. To the contrary, Increasing the clean air quantity or changing the input position of clean air is not good for workers because it causes the exit of respiratory dusts through workers' entrance or cause it to remail suspended in the air in the workplace tank.

• 드라이브 ㆍ 컨트롤
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• 제17권3호
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• pp.9-14
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• 2020

A special purpose machine with two manipulators and quadruped crawler system is being developed to work at disaster sites where it is intended to quickly respond in the initial stages after the event. In this study, a terrain recognition module is developed so that the above special purpose machine can quickly obtain ground information to help choose its path while recognizing objects in its way, this is intended to enhance the remote driver's limited situational awareness. Terrain recognition modules were developed for two tasks (real-time path guidance, precision terrain measurements). The real-time path guidance analyzes terrain and obstacles while moving, while the precision terrain measurement feature provides more accurate terrain information by precisely measuring the ground in front of the vehicle while stationary. In this study, an air-cooled sensor protection module was developed so that the terrain recognition module can continue its vital tasks in the event of exposure to foreign substances, including scattered dust, mist and rainfall, as well as high temperatures.