• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.11
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• pp.1361-1369
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• 2013

This study performs a computational fluid dynamics (CFD) analysis of the inner flow of a multihole injector nozzle by using ANSYS CFX 13.0. Based on the obtained results, a design of experiment (DOE) was performed and applied to investigate the effects of injector nozzle design parameters on cavitation. To analyze the design sensitivity and signal-to-noise ratio (S/N ratio), the hole diameter, hole length, hole angle, and K-factor of the nozzle hole were selected as design parameters, and the effect of these parameters was investigated at 16 experimental points. Consequently, it was found that the effect of the K-factor on the cavitation and inner flow of the injector nozzle is the greatest. Thus, the selection of a suitable K-factor is important in nozzle design considering cavitation flow.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.155-155
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• 2011

신재생에너지 수요가 확대됨에 따라 신재생에너지 관련 제품에 소요되는 물질에 대한 관심이 확대되고 있다. 이들 물질은 공급리스크가 존재하는 희유금속이 주를 이루고 있다. 본 연구에서는 신재생에너지 등의 high tech 기술 확대로 인한 희유금속의 수요 및 공급을 전망하고 있는 미국의 critical raw material 관리 전략을 살펴보고자 한다. 미국은 2010년 12월 미국 에너지성(DOE : Department of Energy)에서 위기 물질 전략(Critical Materials Strategy)에 관한 리포트를 공표하였다. 클린 에너지 기술 4개 분야(영구자석, 선진 전지, 태양전지 박막, 형광 물질)에서 핵심이 되는 물질(희유금속 등)의 수급 불균형이 일어날 가능성에 대해 조사를 실시하여 리스크 평가하여 단기, 중단기로 구분하여 위기물질을 선정하였다. 클린 에너지 기술 4개 분야에서 핵심이 되는 물질(네오디움, 디스프로슘, 코발트, 리튬, 랜턴, 세륨, 테룰, 인듐, 갈륨, 유로피움, 테르비움, 이트륨)의 12광종 수급을 2025년까지 전망한 결과 전체적으로 단기(2010년~2015년)보다 중기(2015년~2025년)에 공급 부족이 확대한다고 예측되었다. 단기적으로는 인듐이 약간 부족하는 것 외에 디스프로슘과 이트륨에 관해서도 공급 부족할 것으로 예측되었다. 중기적으로는 코발트(전지 기술에 사용)와 유로피움(고효율 조명용의 형광 물질에 사용) 외 대상이 된 다른 모든 물질은 공급 부족이 발생할 것으로 전망되었다. 이를 종합하여 단기적으로는 디스프리슘, 유로피움, 인듐, 테르븀, 네오디움, 이트륨 등이, 중기적으로는 디스프리슘, 유로피움, 테르븀, 네오디움, 이트륨 등이 위기물질(Critical Material)로 분석되었다. 에너지성은 위기물질을 공급원다각화, 대체물질개발, 리유즈, 리사이클링 등을 국제적 파트너와 함께 추진하여 리스크를 관리할 것이며, 2011년까지 최신정보를 구축하여 위기물질 전략을 재설정할 예정이다. 체계적인 위기물질 선정 및 관리전략 등을 참조하고, 신재생에너지기술 변화에 따른 원재료의 중요성 및 리스크 관리현황을 기초로 우리나라에 적합한 위기관리 물질 선정 및 관리가 필요할 것이다.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.26 no.1
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• pp.20-29
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• 2016

Objectives: The purpose of this study is to simplify and standardize analytical method of polar solvents(methanol, isopropanol, n-butanol, acetone, methylene chloride and MIBK) in the working environmental by GC. Because NIOSH methods are various and complicated. Methods: The method is using the same stationary phase(5% phenyl 95% dimethylpolysiloxane), absorbent(silica gel) and desorption solvent(DMSO) for above 6 solvents. For the 6 solvents desorption efficiency, calibration curve, and limit of detection were studied Results: As the results, 6 solvents{2 groups ; first group(methanol/isopropanol/butanol) and second group(acetone/methylene chloride/MIBK)} could be separated and quantified within 10 minutes. Desorption efficiency from silica gell of 6 solvents using dimethylsulfoxide(DMSO) was methanol 86.2%, isopropanol 103.2%, n-butanol 101.8%, acetone 98.2%, methylene chloride 103.9% and MIBK 106.2% in the range of 0.2, 0.5, 2.0 times of TWA, consequently, satisfied NIOSH estimation level(beyond 75%). Correlation coefficient(r)in the range of 0.2~2.0 times of TWA, was above 0.999 for 6 solvent. LOD(mg/DMSO ml) using calibration curve in the range of 0.2~2 times of TWA was methanol 0.11, isopropyl alcohol 0.20, n-butanol 0.03, acetone 0.50, methylene chloride 0.05, MIBK 0.04 respectably. Conclusions: This method can be used at the sampling and analytical method for polar solvents by GC. Also, will be able to be applied with NIOSH methods.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.487-487
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• 2012

플라즈마 디스플레이 패널(PDP)은 공정 절차가 간단하고 가격 경쟁력이 매우 뛰어나 일찌감치 대형 평판 디스플레이 시장을 주도해 왔으며 빠른 응답 속도를 기반으로 한 생생한 화질의 구현으로 3D TV 시장에서도 꾸준한 사랑을 받고 있다. 향후 더 큰 화면을 요구하는 PID(Public Information Display) 시장에서도 PDP 는 두각을 나타낼 수 있을 것으로 보인다. 하지만 PDP 는 여전히 LCD, OLED 등의 디스플레이에 비해 발광 효율이 낮고 소비 전력이 높다는 단점을 가지고 있다. 또한 미국 환경청(EPA)과 에너지부(DOE)가 공동으로 마련한 전자 제품의 효율 등급제인 에너지 스타(Energy Star) 제도가 끊임없이 개편되면서 소비 전력에 대한 규제가 점차 강화되고 있기 때문에 발광 효율 및 소비 전력 특성의 개선은 현재 PDP 업계가 해결해야 할 가장 중요한 과제라고 할 수 있다. 발광 효율의 개선과 관련하여 최근에는 PDP의 보호막으로 널리 쓰이고 있는 MgO 보다 2차 전자 방출 계수가 높아 PDP의 구동 전압을 낮추는 동시에 휘도와 발광 효율 특성을 개선시킬 수 있는 신 보호막에 대한 연구가 활발히 이루어지고 있다. MgO를 대체 가능한 신 보호막으로 언급되는 물질은 SrO 혹은 CaO 등이 대표적이다. 하지만 이러한 물질들은 공기 및 수분에 대한 용해도가 높기 때문에 증착된 막이 이후의 공정 과정(합착 및 가열 배기 등)에서 대기 중에 노출 될 경우 심하게 변질될 수 있다. 이러한 문제점을 해결하기 위해서 신 보호막 위에 기존의 MgO 보호막을 얇게 증착하여 공기로부터의 접촉을 차단하거나 펠렛을 제조하는 과정에서 MgO 에 신 보호막 물질을 소량만 첨가하는 등의 방법들이 제안되어 왔으며 그 결과 기존의 PDP 대비 구동 전압을 낮추고 발광 효율을 획기적으로 개선하는데 성공한 결과들이 지속적으로 보고되고 있다. 하지만 신 보호막이 공기 및 수분에 민감한 만큼, 고온의 공정으로 인해 PDP의 하판 유리로부터 상판에 증착된 박막으로 확산되는 불순물에 의해서도 오염되며 이 역시 신 보호막의 특성을 구현하는데 방해 요소로 작용한다. 본 연구에서는 PDP 하판의 불순물이 상판의 박막으로 확산되는 것을 방지하고자 하판 형광체 인쇄전 PECVD 증착법으로 확산 방지막을 1 가량 형성하였다. 이후 SIMS 분석을 통하여 하판 불순물의 확산이 효과적으로 차단됨을 확인하였고 신 보호막의 오염을 최소화하여 결과적으로 PDP의 구동 전압을 낮추고 효율을 획기적으로 개선하는데 기여할 수 있음을 확인하였다.

• Applied Chemistry for Engineering
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• v.19 no.2
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• pp.179-184
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• 2008

The separation and purification of succinate are necessary for the succinic acid production by a fermentation process. Among the purification processes, desalination of succinate is inevitable. In this work, electrodialysis was selected as a desalination method and its operating parameters affecting the degree of desalination and energy consumption were examined. Commercialized electrodialysis apparatus was used in this work and its optimum operating parameters were determined by using design of experiment (DOE) method. Voltage, concentration of succinate, and pH were selected as main parameters. Among them, voltage seemed to be the most important one. The final conversion of succinate to succinic acid was calculated when the operating parameters were optimized. Finally, the effect of impurities, such as corn steep oil, yeast extract, and dextrose on the electrodialysis efficiency was also studied.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.8
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• pp.4729-4735
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• 2014

To protect the environment, the regulation of emissions from off-road engines which are relatively neglected, is being reinforced. This paper deals with the robust design of off-road diesel engines considering the emission characteristics. Measurements of the NOx and PM levels based on the DOE were carried out. The injector hole number, injection timing and EGR rate were selected as the control factors. The orthogonal arrays table $L_9(3^3)$ was made from 2 or 3 levels for each factor and measurements of emissions were accomplished based on the table. The small-the-better SN ratio according to the Taguchi method was evaluated. The ANOVA (analysis of variance) for the SN ratio was conducted. The injection timing on the NOx emissions and the EGR rate on the PM have the largest effect on the low-load operation condition. The confidence levels of the control factors were more than 90%.

• Journal of Navigation and Port Research
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• v.30 no.8 s.114
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• pp.685-690
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• 2006

The rail clamp is the device to prevent that a crane slips along rails due to the wind blast as well as to locate the crane in the set position for loading and unloading containers. The wedge typed rail clamp should be designed to consider the structural stability and the durability because it compresses both rail side with large clamping force by the wedge working as the wind speed increases. In this research, the design of experiments(DOE) and the variation technology(VT) built in ANSYS WORKBENCH are utilized to determine the optimum shape of a jaw. The optimum results obtained by two methods are compared and examined.

• Journal of Energy Engineering
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• v.24 no.4
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• pp.24-32
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• 2015

National and international regulations on the exhaust gases of diesel engines are being strengthened, and a study of the combutsion engine and the post-porcessing system are in progress as a variety of ways. There are many techniques for the removal of nitrogen oxide like HC-SCR, LNT, Urea-SCR. And the technical development on the Urea-SCR owing to high conversion efficiency and fuel economy characteristics has being processed. This study investigated the physical/chemical properties of urea according to the change of the urea content, and were analysed the characteristic of exhaust gas. According to the increase of urea content, the contests of biuret aldehyde, phosphate content was increased and the changes of emission quantity of carbon monoxide, hydrocarbons and particulate matter in the exhaust gas was very slight. The emission quantity of NOx was decreased in accordance with increasing the urea content and it was shown to be more than 80 % in the urea solution having more than 30 wt%.

• Journal of the Korean Ceramic Society
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• v.40 no.10
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• pp.936-942
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• 2003

In order to develop glass formulations for vitrifying Low-and Intermediate-Level radioactive Wastes (LILW) from nuclear power plants of Korea Hydro & Nuclear Power (KHNP) Co., Ltd., promising glass formulations were selected based on glass property model predictions for viscosity, electrical conductivity and leach resistance. Laboratory measurements were conducted to verify the model predictions. Based on the results, the models for electrical conductivity, US DOE 7-day Product Consistency Test (PCT) elemental release, and pH of PCT leachate are accurate for the LILW glass formulations. However, the model for viscosity was able to provide only qualitative results. A leachate conductivity test was conducted on several samples to estimate glass leach resistance. Test results from the leachate conductivity test were useful for comparison before PCT elemental release results were available. A glass formulation K11A meets all the KHNP glass property constraints, and use of this glass formulation on the pilot scale is recommended. Glass formulations K12A, K12B, and K12E meet nearly all of the processing constraints and may be suitable for additional testing. Based on the comparison between the measured and predicted glass properties, existing glass property models may be used to assist with the LILW glass formulation development.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.6
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• pp.513-519
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• 2014

For depth machining in die and mold, Electrical Discharge Machining (EDM) is used generally. To make deep hole and deep shape efficiently, cemented carbide endmill for depth machining is necessary. For this purpose, cemented carbide endmill was designed using design of experiment (DOE). To improve cutting performance, endmill was coated with multilayer surface treatment, TiAlCrSiN and TiAlCrN, for higher wear resistance. In order to evaluate the endmill, Transverse Rupture Strength (TRS) test was tried for investigating the relationship between surface treatment and strength in endmill body. Scratch test was also used for measuring adhesion force of each surface treatment. To evaluate hardness of surface treatment, Atomic Force Microscope (AFM) analysis was carried out. Wear test was executed for characteristics of each surface treatment in high temperature. Consequently, TiAlCrSiN was superior to the TiAlCrN coating in case of high temperature environment such as cutting.