• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.465-465
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• 2009

Wind power is one of the most reliable renewable energy sources and the installed wind turbine capacities are increasing radically every year. Although wind power has been favored by the public in general, the problem with the impact of wind turbine noise on people living in the vicinity of the turbines has been increased. Low noise wind turbine design is becoming more important as noise is spreading more adverse effect of wind turbine to public. This paper demonstrates the design of 10 kW class wind turbines, each of three blades, a rotor diameter 6.4m, a rated rotating speed 200 rpm and a rated wind speed 10 m/s. The optimized airfoil is dedicated for the 75% spanwise position because the dominant source of a wind turbine blade has been known as trailing edge noise from the outer 25% of the blade. Numerical computations are performed for incompressible flow and for Mach number at 0.145 and for Reynolds numbers at $1.02{\times}10^6$ with a lift performance, which is resistant to surface contamination and turbulence intensity. The objective in the low design process is to reduce noise emission, while sustaining high aerodynamic efficiency. Dominant broadband noise sources are predicted by semi-empirical formulas composed of the groundwork by Brooks et al. and Lowson associated with typical wind turbine operation conditions. During the airfoil redesign process, the aerodynamic performance is analyzed to minimize the wind turbine power loss. The results obtained from the design process show that the design method is capable of designing airfoils with reduced noise using a commercial 10 kW class wind turbine blade airfoil as a basis. The new optimized airfoil clearly indicates reduction of total SPL about 3 dB and higher aerodynamic performance.

• 한국식품위생안전성학회지
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• 제28권2호
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• pp.95-98
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• 2013

Streptococcus suis (S. suis) is a major swine pathogen and an emerging zoonotic agent and is an increasing public health problem across Asia. The present study was undertaken to estimate the antibacterial effect of GR extract and therapeutic effect of GR extract against S. suis infection in mice. At the concentration of GR extract 2.5 mg/ml, the antibacterial effect was not shown on S. suis. However, the antibacterial effect against S. suis was observed at the concentration of GR extract 5.0 mg/ml. Oral administration of GR extract at the dose of 10 mg/kg showed a therapeutic effect for S. suis infected BALB/c mice. The mortality of GR extract-treated mice at the concentration of 5, 10 and 20 mg/kg was 80%, 70%, and 50% at 12 days, respectively, while that of untreated mice was 100% at 8 days after a lethal dose of S. suis infection. The results of our study strongly indicate that GR extract has potential as an effective for S. suis infection in mice.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.376-379
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• 2006

Reaction Wheel Assembly (RWA) is one of the major disturbance sources that have influence upon the Line of Sight (LOS) of payload. A micro-vibration induced by RWA is propagated through the satellite structure and decrease the LOS stability performance of payload. This effect shall be analyzed through the jitter analysis. If a requirement or specification of payload jitter level is found to be not satisfied according to the jitter analysis campaign, some modification or redesign should be done on the satellite structure or a couple of isolator should be attached on the RWA interface in order to reduce the transmitted vibration level of RWA. The purpose of ???RWA isolator test? is to roughly evaluate the performance of vibration suppression level with a passive RWA isolator made of rubber. For this test, actual RWA is used as a vibration source and a couple of cube-shaped rubber mount designed for satellite is used as a passive isolator. There may be several considerations in order to accommodate RWA isolator to spacecraft such as not only vibration reduction performance but also thermal conduction problem, mechanical size, RWA alignment problem, etc. But in this report the feasibility of RWA isolator is analyzed only in a vibration suppression point of view. As a result, high frequency vibration of RWA above 50Hz is perfectly attenuated with isolators, however, first harmonic components below 50Hz became larger due to the additional low frequency resonance modes of roll, pitch, yaw rigid body motion of RWA+bracket.

• 한국의류학회지
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• 제28권1호
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• pp.45-53
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• 2004

This study was conducted to redesign hotel robes based on Korean images. Hotel robes are furnished at many Korean hotels to increase the level of their guests' satisfaction toward their hotel services. The current hotel robe has several flaws in utility and design. Also, the robes register a low level on guests' satisfaction while generating high cleaning cost. Consequently, improvements in the hotel robes' material, motifs, style, and color were needed. The current one-piece, cotton towel weave robes used in hotels are white and pale. Half of the hotel guests never wear the hotel robes during their stay, because they are unattractive and most Korean hotels provide a robe similar in design. Furthermore, these robes are undistinguishable from those found at other countries. Nevertheless, Korean hotel managers feel that the hotel robe is an important tool to express its hotel image and to increase guests' satisfaction of their services. Most hotel managers and consumers agreed that it is necessary to design hotel robes based on Korean images. They believe that redesigning the hotel robes based on Korean images would induce hotel guests to wear them and at the same time feel part of the Korean traditional culture. The Korean traditional motifs of Taegug, Un (cloud), JuJag (phoenix), and Kumkwan (gold crown) were used in the new design of the hotel robes. The style of new hotel robes is the Korean traditional Pho of the Three Kingdoms. The colors of new hotel robes are white and pink. Forty-three examiners evaluated the newly designed robes for their aesthetic, symbolic and distinctional values. They concurred that the new robes were much better than the current ones.

• 공학교육연구
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• 제11권3호
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• pp.24-32
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• 2008

한국의 공과대학의 교육 목표는 1) 전공교육의 강화, 2) 팀워크능력, 커뮤니케이션 스킬, 비판적 사고력 등을 포함하는 공과대학 소양의 함양 두 가지로 요약될 수 있다. 이 두 가지 교육 목표를 달성하기 위한 시도로 제안된 것이 공학소양교육이다. 현재 공과대학의 교양교육 개선안에는 전공에 구애받지 않는 보편적 교양교육을 강조하고 있는 미국형과 일반 교양교육과 구분되는 공학소양교육의 필요성을 강조하는 한국공학교육인증원형으로 구분된다. 본 연구는 한국공학교육인증원의 공학소양교육과정을 교육과정 개편에 적용한 서울대학교 공과대학의 교양 교육과정 개편 내용과 그 의미를 탐색하였다. 이 논문에 제시된 서울대학교 공과대학 교양교육 개선안은 교양교육의 학점 중 학생들의 자유선택 과목의 비중을 줄이고, 공학소양교육으로 이수하게 하는 방안을 포함하고 있다. 이 방안은 전공에 구애받지 않는 공통적 교양교육의 틀을 지키면서 전공과 단과대학의 특성을 반영하는 전공소양형 교양교육을 강조하는 현실적 방안으로 평가될 수 있다.

• 센서학회지
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• 제8권2호
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• pp.139-147
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• 1999

본 논문에서는 관성 항법 장치 및 동작 제어 장치 능에서 회전 각속도를 검출하기 위하여 널리 사용되는 동조 자이로스코프의 새로운 각속도 검출방법을 제시하였다. 제안된 방법은 자이로스코프의 모델을 사용하여 재평형 루프의 설계를 수행함으로써 기존의 PI제어 방법만을 사용하였을 경우보다 외부 입력에 대하여 속도 검출을 위한 픽업단의 회전각도가 과도 및 정상 상태에서 작은 검출각을 유지시킨 상태에서 입력 각속도를 검출할 수 있으며 이에 따라 자유 자이로스코프의 기계적인 변경 없이도 시스템의 동작 범위를 매우 넓히는 것이 가능함을 보였다. 제안된 방법을 사용한 동조자이로스코프 시스템의 모델 및 전달 특성을 제시하였으며 최종적으로 컴퓨터 모의실험 모델 및 그 결과를 제시하여 그 타당성을 확인하였다.

• 한국식품위생안전성학회지
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• 제27권3호
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• pp.290-294
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• 2012

Vibrio spp. and Streptococcus spp. have caused a considerable disease of farmed fish and economic loss in fish farming and seafood industry. In this study, the efficacy of an aquatic disinfectant tablet composed to calcium hypochlorite was evaluated against V. anguillarum and S. iniae. A bactericidal efficacy test by broth dilution method was used to determine the lowest effective dilution of the disinfectant following exposure to test bacteria for 30 min at $4^{\circ}C$. An aquatic disinfectant tablet and test bacteria were diluted with distilled water (DW), hard water (HW) or organic matter suspension (OM) according to treatment condition. V. anguillarum on the DW, HW and OM condition was completely inactivated with 16,000 15,000 and 13,000 fold dilutions of the disinfectant, respectively. On the DW, HW and OM condition, S. iniae was absolutely inactivated with 17,000 16,000 and 14,000 fold dilutions of the disinfectant, respectively. As an aquatic disinfectant tablet possesses bactericidal efficacy against fish pathogenic bacteria such as V. anguillarum and S. iniae this disinfectant solution can be used to control the spread of fish infective bacterial diseases.

• 한국콘텐츠학회논문지
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• 제12권2호
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• pp.322-330
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• 2012

본 연구는 Hackman and Oldham의 직무특성이론에 근거하여 대학생을 대상으로 자원봉사활동 직무특성이 활동만족도와 지속의지에 미치는 효과를 분석하였다. 이를 위해 강원도내 6개 대학의 대학생 261명을 대상으로 설문조사를 실시하여 자료를 분석하였다. 연구 결과 대학생의 자원봉사참가율은 평균 71.6%로 나타났으며, 자원봉사활동의 직무특성과 활동만족도, 지속의지는 중간값 보다 낮은 수준으로 나타났다. 자원봉사 활동만족도에 미치는 직무특성의 효과에서는 기술다양성과 과업정체성, 피드백이 유의한 수준에서 영향을 미치는 것으로 나타났고, 지속의지에 대해서는 자율성을 제외한 기술다양성, 과업정체성, 과업중요성, 피드백 모두가 영향을 미치는 것으로 나타났다. 또한 상관분석을 통해 자원봉사 활동만족도가 높으면 지속의지 역시 높아지는 것을 알 수 있다. 따라서 자원봉사관리자는 자원봉사활동의 직무를 직무특성이론에 기초하여 설계(design)함으로써 의미충만감이나 책임감, 결과의식을 높여서 최종적으로는 자원봉사를 통한 동기부여와 성과 향상으로 이어져야 할 것이다.

• 산업경영시스템학회지
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• 제40권2호
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• pp.145-149
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• 2017

One of the challenges facing precision manufacturers is the increasing feature complexity of tight tolerance parts. All engineering drawings must account for the size, form, orientation, and location of all features to ensure manufacturability, measurability, and design intent. Geometric controls per ASME Y14.5 are typically applied to specify dimensional tolerances on engineering drawings and define size, form, orientation, and location of features. Many engineering drawings lack the necessary geometric dimensioning and tolerancing to allow for timely and accurate inspection and verification. Plus-minus tolerancing is typically ambiguous and requires extra time by engineering, programming, machining, and inspection functions to debate and agree on a single conclusion. Complex geometry can result in long inspection and verification times and put even the most sophisticated measurement equipment and processes to the test. In addition, design, manufacturing and quality engineers are often frustrated by communication errors over these features. However, an approach called profile tolerancing offers optimal definition of design intent by explicitly defining uniform boundaries around the physical geometry. It is an efficient and effective method for measurement and quality control. There are several advantages for product designers who use position and profile tolerancing instead of linear dimensioning. When design intent is conveyed unambiguously, manufacturers don't have to field multiple question from suppliers as they design and build a process for manufacturing and inspection. Profile tolerancing, when it is applied correctly, provides manufacturing and inspection functions with unambiguously defined tolerancing. Those data are manufacturable and measurable. Customers can see cost and lead time reductions with parts that consistently meet the design intent. Components can function properly-eliminating costly rework, redesign, and missed market opportunities. However a supplier that is poised to embrace profile tolerancing will no doubt run into resistance from those who would prefer the way things have always been done. It is not just internal naysayers, but also suppliers that might fight the change. In addition, the investment for suppliers can be steep in terms of training, equipment, and software.

• 설비공학논문집
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• 제7권3호
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• pp.406-420
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• 1995

As concerns increase over the dangers of environmental destruction on a global scale, CFC regulations have finally been carried out and some CFC's are expected to be phased out by the end of 1995. The research for alternative refrigerants is very demanding. The major activities related to alternative refrigerants are focused on two different areas; one is the development of mixed refrigerants by using the existing refrigerants, and the other is the development of new HFC refrigerants. One of the most promising alternative refrigerant for CFC-12 is HFC-134a. HFC-134a has often been used as a replacement of CFC-12 for automotive air-conditioners. However, due to different thermodynamic properties of HFC-134a, performances of the replaced system are degraded compared with those of the CFC-12 system. Sometimes, the complete redesign of the system is required. In order to analyse and design the new system effectively, the developement of a system simulation program, in which HFC-134a can be selected as a refrigerant, is recommended. Therefore, the summary of this research is as follows : (1) The various thermodynamic properties of HFC-134a are ana lysed and programmed. (2) The model for serpentine heat exchanger is developed and programmed. (3) These subroutines are integrated to develop to develop an automotive air conditioning system simulation program which is verified by the test results. (4) The verified program is used to analyse the performance of a selected automotive air conditioning system.