• 농촌지도와개발
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• 제6권2호
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• pp.119-139
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• 1999

While many factors could be mentioned to the rapid development of Israel for the last 50 years, it could not be overemphasized the critical role of large scale influx of Jewish immigrants not only in the process of achieving national independence but to the development of modernization. It is well known that mass influx of people in a relatively short period of time may cause serious social problems in various areas such as housing shortage, increasing crime rate, etc. Nontheless, Israel is avidly recognized as a country that successfully overcome such problems by means of creating systematic social integration systems and practicing various adaptation assistance programs for new immigrants. This study was concerned with such a successful social adaptation-assistance programs of Israel for large scale immigrants those who came from all over the world with different socio-economic background. In order to answer the research questions, following two areas of topics were researcher`s main concern. First, organizational structure and functions of the Ministry of Immigrant Absorption of Israel and Jewish Agency that are primarily responsible for the economic, occupational, social, and cultural integration of immigrants during their first three years (five years for housing-aid) in Israel. Second practical adaptation assistance programs such as direct absorption basket, Ulpan, Aliyah 2000, special projects of Keren Hayesod and two of Aliyah Absorption Centers are examined. And lastly some of implications and suggestions are provided in the conclusion section in relation with social adaptation-assistance and integration of reunified Korea, especially from the point of North Koreans.

• 한국전산유체공학회지
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• 제18권4호
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• pp.1-8
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• 2013

The performance of small-size impellers with ruled surfaces was investigated for flank milling over a wide speed range, using computational fluid dynamics analyses and gas bench tests. An impeller with a ruled surface was designed, manufactured, and tested to evaluate the effects of blade loading, the backsweep angle, and the relative velocity distribution on the compressor performance. The simulations and tests were completed using the same compressor cover with identical inlet and outlet channels to accurately compare the performance of the abovementioned impeller with a commercial impeller containing sculptured blades. Both impellers have the same number of blades, number of splitters, and shroud meridional profiles. The backsweep angles of the blades on the ruled impeller were selected to work with the same pinched diffuser as for a sculptured impeller. The inlet-to-exit relative velocity diffusion ratio and the blade loading were provided to maximize the flow rate and to minimize the surge flow rate. The design flow rate, rpm, were selected same for both impellers. Test results showed that for the compressor stage with a ruled impeller, the efficiency was increased by 0.32% with an extended surge margin without a reduction in the pressure ratio as compared to the impeller with the sculptured design. It was concluded that an increased relative velocity diffusion coupled with a large backsweep angle was an effective way to improve the compressor stage efficiency. Additionally, an appropriate blade loading distribution was important for achieving a wide operating range and higher efficiency.

• Tribology and Lubricants
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• 제32권4호
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• pp.125-131
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• 2016

In recent years, thick ta-C coating has attracted considerable interest owing to its existing and potential commercial importance in applications such as automobile accessories, drills, and gears. The thickness of the ta-C coating is an important parameter in these applications. However, the biggest problems are achieving efficient coating and uniformity over a large area with high-speed deposition. Feasibility is confirmed for the ta-C coating thickness of up to 9.0 µm (coating speed: 3.0 µm/h, fixed substrate) using a single FCVA cathode. The thickness was determined using multiple coating cycles that were controlled using substrate temperature and residual stresses. In the present research, we have designed a coating system using FCVA plasma and produced enhanced thick ta-C coating. The system uses a specialized magnetic field configuration with stabilized DC arc plasma discharge during deposition. To achieve quality that is acceptable for use in automobile accessories, the magnetic field, T-type filters, and 10 pieces of a multi-cathode are used to demonstrate the deposition of the thick ta-C coating. The results of coating performance indicate that uniformity is ±7.6 , deposited area is 400 mm, and the thickness of the ta-C coating is up to 5.0 µm (coating speed: 0.3 µm/h, revolution and rotation). The hardness of the coating ranges from 30 to 59 GPa, and the adhesion strength level (HF1) ranges from 20 to 60 N, depending on the ta-C coating.

• Tribology and Lubricants
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• 제32권4호
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• pp.132-139
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• 2016

The piston of a marine diesel engine works under severe conditions, including a combustion pressure of over 180 bar, high thermal load, and high speed. Therefore, the analyses of the fatigue strength, thermal load, clamping (bolting) system and lubrication performance are important in achieving a robust piston design. Designing the surface profile and the skirt ovality carefully is important to prevent severe wear and reduce frictional loss for engine efficiency. This study performs flexible multi-body dynamic and elasto-hydrodynamic (EHD) analyses using AVL/EXCITE/PU are performed to evaluate tribological characteristics. The numerical techniques employed to perform the EHD analysis are as follows: (1) averaged Reynolds equation considering the surface roughness; (2) Greenwood_Tripp model considering the solid_to_solid contact using the statistical values of the summit roughness; and (3) flow factor considering the surface topology. This study also compares two cases of skirt shapes with minimum oil film thickness, peak oil film pressure, asperity contact pressure, wear rate using the Archard model and friction power loss (i.e., frictional loss mean effective pressure (FMEP)). Accordingly, the study compares the calculated wear pattern with the field test result of the piston operating for 12,000h to verify the quantitative integrity of the numerical analysis. The results show that the selected profile and the piston skirt ovality reduce friction power loss and peak oil film pressure by 7% and 57%, respectively. They also increase the minimum oil film thickness by 34%.

• 한국산업보건학회지
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• 제15권3호
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• pp.270-276
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• 2005

This study was conducted to examine whether a specific synthetic metalworking fluid (MWF), "A", in use for 10 months without replacement, displayed microbial resistance and to identify the additives associated with the control of microbial growth. Three synthetic MWF products ("A", "B", and "C") were studied every week for two months. Microbial deterioration of the fluids was assessed through evaluation by endotoxin, bacteria and fungi levels in the MWFs. In addition, formaldehyde, boron, ethanolamine, and copper levels were also studied to determine whether they influence microbial growth in water-based MWFs. Throughout the entire study in the sump where MWF "A" was used, bacteria counts were lower than 103 CFU/mL, and endotoxins never exceeded 103 EU/mL. These levels were significantly lower than levels observed in sumps badly deteriorated with microbes. Boron levels in MWF "A" ranged from 91.7 to 129.6 ppm, which was significantly higher than boron levels found in other MWF products. The total level of ethanolamine (EA) in MWF "A" ranged from 35,595 to 57,857 ppm (average 40,903 ppm), which was over ten times higher than that found in other MWFs. Monoethanolamine (MEA), diethanolamine (DEA) and triethanolamine (TEA) concentrations in MWF "A" were also significantly higher than seen in other MWFs. However, although EA and boron might improve anti-microbial performance, their abuse can pose a serious risk to workers who handle MWFs. From an industrial hygiene perspective, our study results stress that the positive synergistic effect of boron and EA in reducing microbial activity in MWF must be balanced with the potentially negative health effects of such additives. Our study also addresses the disadvantage of failing to comprehensively report MWF additives on Material Safety Data Sheets (MSDS). Future research in MWF formulation is needed to find the best level of EA and boron for achieving optimal synergistic anti-microbial effects while minimizing employee health hazards.

• 인터넷정보학회논문지
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• 제3권3호
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• pp.11-17
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• 2002

웹을 통한 원격교육은 시간과 공간의 문제를 극복할 수 있다는 큰 장점에도 불구하고 강의실 및 집합교육에 비해 연수생 관리가 취약하다는 문제점을 지니고 있다. 이러한 문제는 원격교육활동의 성취수준 및 목표도달에 대한 커다란 장애로 부담이 되고 있고 원격교육담당자에게 많은 고민을 안겨주고 있다. 원격교육담당자는 원격교육활동에 대한 연수생의 참여와 반응을 계속적으로 모니터링 해야 하고 이에 대한 적절한 피드백을 연수생에게 제공하여야 함에도 불구하고 기존의 원격교육시스템은 교수학습활동에 중점을 둔 나머지 원격교육활동에 대한 효율적 관리기능을 제공하지 못하고 있다. 따라서 본 논문에서는 원격교육의 일환으로 실시되고 있는 원격교원연수의 효율적 운영이 가능하며 교원연수가 목표로 하는 성취수준의 효과적 달성을 위해 원격교원연수의 적합한 관리요소를 추출하고 이를 시스템 또는 연수 관리자가 연수과정에 적용하여 연수생에 대한 적절한 피드백의 제공이 가능한 원격교원연수 관리시스템을 효율적으로 구현하였으며 교육과정과 컴퓨팅 환경에 따라 시스템의 유연한 변경도 가능하게 되었다.

• 인터넷정보학회논문지
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• 제10권4호
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• pp.199-211
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• 2009

최근 무선네트워크 기술은 이동 응용프로그램을 위해 이종통신망 연결패스 상에서 병렬로 스트라이핑 데이터 기술을 이용해 고속 데이터를 전달을 가능케 한다 [2]. 전통적으로 대역폭지연프로덕트(BDP) 기반에서 고속전송은 송신자 측에서 다중 TCP 소켓의 튜닝을 요구한다. 더욱이, 메모리와 네트워크 요구의 균형을 유지하는 ATBT같은 기술은 유선기반의 단일 소켓상에서 하나의 플로우만 가정하여 설계되었다. 그러므로 본 논문은 여러 무선 패스를 경유하는 이종 무선네트워크 상에서 고속전송을 가능케하는 스트라이핑 전송기술에 적합한 버퍼튜닝 기술을 제안한다. 제안 기술은 이동성, 링크손실, 대역폭변동성 등의 특징을 지닌 무선 멀티홈 모바일 호스트상에서 작동하는 전송계층에서의 자원관리기술이다. 실험을 통하여 유선기반의 ATBT를 본 환경에 적용한 것보다 메모리, 평균 전송량에 있어 제안 기술의 성능이 우수하다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 추계학술대회 초록집
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• pp.87.2-87.2
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• 2011

Many type of fuel cell stacks have been developed to improve the efficiency of reactants usage. The cascade type fuel cell stack using dead end operation is able to attain above 99% usage of hydrogen and oxygen. It is sectionalized to several parts and the residual reactants which are used previous parts would be supplied again to next parts which have less number of cells in dead end operation stack. The oversupply of reactants which is usually 120%~150% of the theoretical amount to generate current for preventing the flooding effect could be provided to each part except the last one. The final section which is called monitoring cells is supposed to be supplied insufficient the fuel or oxidant that would have some accumulated inert gas from former parts. It makes some voltage drop in the part and the fresh reactants must be supplied to the part for recovering it by venting the residual gas. So the usage of fuel and oxidant is depend on the time and frequency of opening valves for venting of residual gas and it is important to optimize the vent logic for achieving higher usage of hydrogen and oxygen. In this research, many experiments are performed to find optimal condition by evaluating the effect of time and frequency under several power conditions using over 100kW class fuel cell module. And the characteristics of the monitoring cells are studied to know the proper cell voltage which decide the condition of opening the vent valve for stable performance of the cascade type fuel cell module.

• 공업화학
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• 제18권5호
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• pp.506-510
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• 2007

전기적 특성을 가지는 4,4',4''-tris(N-(1-naphthyl)-N-phenylamino)-triphenylamine (1-TNATA)가 유기발광소자(OLED)에서 전극으로 사용되는 ITO (Indium Tin Oxide)와 홀 수송층(Hole Transport Layer, HTL) 사이에 박막으로 진공증착되었다. 분자배열이 잘 되어진 1-TNATA의 경우 ITO와 홀 수송층 사이의 계면에서 생기는 전하주입장벽을 줄임으로 소자의 안정성과 효율을 높여준다. 본 연구에서의 라만 스펙트라(Raman spectra) 분석 결과, 증착된 1-TNATA 박막의 열처리와 증착하는 동안 전자기장 처리에 의해서 박막이 집적되고 분자배열이 이루어짐을 확인하였다. 열처리를 한 경우 1-TNATA 박막으로의 전류 흐름이 25% 증가하였다. 또한, $110^{\circ}C$에서 열처리한 1-TNATA 박막으로 제조된 다층유기발광소자의 전원 효율과 발광효율이 향상되었다. 열처리한 박막이 전자기장으로 처리한 박막에 비해 높은 효율을 나타내었다.

• 대한한의학회지
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• 제19권2호
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• pp.211-227
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• 1998

Benign Prostatic Hyperplasia(BPH) is the most common benign tumor seen in the western male, and it is found in 50% of men over 50 years of age. It is characterized by the formation of large discrete lesions in the periurethral region. As they enlarge, these nodules tend to compress the urethra and cause partial or almost complete obstruction of .urine flow. The etiology of BPH is uncertain, but the increasing incidence with advancing age suggests the possibility of an imbalance between male and female sex hormones. In the past, most patients have had multiple indications to support the decision to initiate therapy. But both the urologic surgeon and the patient must be clearly aware of the results that can be expected and the risks involved in achieving them. The aims of this study are to investigate and summarize the current trends of treatment for BPH so as to suggest the effective and available way to treat the disease. In Oriental medicine, the BPH is recognized as uroschesis and ischuria, and the etiology is mainly in stagnated blood and insufficiency of the kidneys. The point of treatment of BPH is recovery of urination, and the treatment can be approached in two ways through herb drugs and acupuncture. Some of the herb drugs have substances which reduce BPB. Acupuncture therapy stimulates the pelvic plexus and is reported to be effective for voiding. Suppository, massotherapy, rectal injection, locus injection and attachment of herb drugs to the navel or the acupoint are announced as the effective treatments. So, this study of the approach and application of these treatments on BPH would be necessary.