• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.172-175
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• 2002

High speed machining is one of the most effective technologies to improve productivity. It can give great advantage for manufacture of die and Moulds. However, when machining of micro groove in high speed machining a severely thermal damage was generated on workpiece and cutting tool. Generally, the cutting fluid is used to improve penetration. lubrication. and cooling effect. In order to rise the performance of lubrication. it contains extreme pressure agents (Cl, S, P). But the environment of work room go bad by those additive. Therefore, the compressed chilly air with oil mist system was developed to replace the conventional cutting fluid system. This paper carried out the tests to evaluate the machinability by the cutting environment in high speed micro groove machining of NAK80 (HrC40). Compressed chilly air with oil mist was ejected on the contact area between cutting edge and workpiece. The effect of this developed compressed chilly air with oil mist system was evaluated in terms of tool life. The results showed that the tool lift of carbide tool coated TiAlN with compressed chilly air mist cooling was much longer than that of the dry and flood coolant when cutting the material.

• 디지털융복합연구
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• 제11권1호
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• pp.283-288
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• 2013

본 논문에서는 실내 환경에서 전파특성 분석에 유용한 마이크로 셀용 3D 시뮬레이터를 제시하였다. 지금까지 소개된 대부분의 전파특성 분석 결과들은 2차원 평면에서 거리에 따른 신호의 손실(Path Loss) 위주로 연구가 진행 되었다. 본 연구에서는 실내에서 전파특성을 분석하기 위해 다양한 ITU 모델을 사용하여 입체구조의 실내 환경에서 전파의 수신신호의 세기에 대한 분석을 수행하였다. 시뮬레이션에서 나타난 결과를 분석해보면 저 주파수(150MHz-400MHz) 대역과 고주파수 대역(2GHz-6GHz) 에서 전파특성이 많은 차이를 나타내고 있다. 그리고 각 수신기의 위치에서 수신 신호는 전파경로상의 벽면에서 손실되는 전력에 따라 차이가 생기기 때문에 송신기의 출력도 중요한 요인으로 분석되었다.

• 가정과삶의질연구
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• 제22권5호
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• pp.59-73
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• 2004

Since 1980s' Korea had a great change on the housing culture by the supply of multi-family housing stock both on the macro-social and micro-social aspects. The purpose of this study was to examine the changes and the characteristics of housing environments which were estimated its modernization, and to examine the personal life under the change of housing environments. So I would like to revaluation the characteristics of modernization between the 1980s' and 1990s'. Therefore references were made to various papers, reports, the statistical data, newspaper reports, advertisements and magazines during that period. As a result, this paper came to the remarks as follows: 1. The success of modernization on the housing environments since 1980s' was the Quantitative growth of housing supply by multi-family housing. In spite of this, the Quantitative growth of housing supply and the improvement in Quality like housing space per person had the characters which was 'out of valence on the division'. 2. The Qualitative improvement of modem housing life by the development of housing industries could be said the improvement owing to develop of facilities and equipments. The introduction of up-to-date facilities and equipments realized the convenience and the rationality of living in the house. Although the improvement on the physical things deteriorated the modernized spaces to uniform things by commercial strategies. 3. The life in the multi-family housing which gives protection to personal privacy was settle down on the extremely individualized life without common things within the neighbors. Multi-family housing which was a production of process of modernization came true the growth in an appearance and the variety in the inside, but for the aspect of residents' everyday life in the multi-family housing, the Korean traditional relationship was collapsed and a sense of incompatibility within the residents was created.

• Structural Engineering and Mechanics
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• 제65권2호
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• pp.191-201
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• 2018

The corrosion environments in a steel structure are significantly different depending on the individual parts of the members. To ensure the safety of weathering steel structures, it is important to evaluate the time-dependent corrosion behavior. Thus, the progress and effect of corrosion damage on weathering steel members should be evaluated; however, the predicted corrosion depth, which is affected by the corrosion environment, has not been sufficiently considered until now. In this study, the time-dependent thicknesses of the corrosion product layer were examined to quantifiably investigate and determine the corrosion depth of the corroded surface according to the exposure periods and corrosion environments. Thus, their atmospheric exposure tests were carried out for 4 years under different corrosion environments. The relationship between the thickness of the corrosion product layers and mean corrosion depth was examined based on the corrosion environment. Thus, the micro corrosion environments on the skyward and groundward surfaces of the specimens were monitored using atmospheric corrosion monitor sensors. In addition, the evaluated mean corrosion depth was calculated based on the thickness of the corrosion product layer in an atmospheric corrosion environment, and was verified through a comparison with the measured mean corrosion depth.

• 한국식품과학회지
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• 제49권1호
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• pp.110-116
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• 2017

감마오리자놀의 산화안정성을 증진시키기 위해 천연 다당류인 펙틴과 칼슘이온의 이온결합을 이용한 펙틴 겔 미세캡슐과 나노캡슐을 제조하였다. 캡슐의 입자특성은 펙틴, 염화칼슘, 감마오리자놀 농도와 경화시간 변화에 영향을 받았으며, 포집 효율과 방출 조절 측면에서 가장 효과적이었던 펙틴 2%, 염화칼슘 4%, 경화시간 60분에서 제조한 미세캡슐과 펙틴 0.05%, 염화칼슘 4%, 감마오리자놀 5%에서 제조한 나노캡슐을 선정하였다. 입자 크기에 따른 두 캡슐 제형에 대한 비교분석 결과, 감마오리자놀 포집 효율은 입자 크기 증가로 인한 내부 포집공간 증가로 미세캡슐에서 더 높게 나타났으며, 이는 유효량 섭취의 효율측면에서 경구투여에 적합한 것으로 판단되었다. 감마오리자놀 함유 펙틴 캡슐 모두가 산성에서 방출이 억제되고 중성으로 갈수록 방출이 촉진되어 체내 소화환경에서 효과적인 전달체의 특성을 보였으며, 미세캡슐에 비해 나노캡슐의 방출 조절이 더 효과적으로 나타나 감마오리자놀의 장기 저장과 활성유지에 더 적합한 것으로 판단되었다. FTC법을 통한 지질산화 저해능 평가에서는 저장 5일 이후 유리 감마오리자놀의 산화방지 활성이 감소한 데 반해 감마오리자놀 함유 미세와 나노캡슐은 지속적인 지방산화 억제활성을 지속적으로 유지하였다. 본 연구를 통해 미세와 나노캡슐화는 감마오리자놀의 안정성 및 지질산화 활성 증대에 효과적이며, 제형 특성에 따라 다양한 용도로 활용 될 수 있을 것으로 판단된다.

• Computers and Concrete
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• 제19권5호
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• pp.443-449
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• 2017

Taking high geothermal tunnels as background, the deformation of concrete for shotcrete use was studied by simulating hot-humid and hot-dry environments in a laboratory. The research is made up by two parts, one is the influence of two kinds of high geothermal environments on the deformation of shotcrete, and the other is the shrinkage inhibited effect of fiber materials (steel fibers, polypropylene fibers, and the mixture of both) on the concrete in hot-dry environments. The research results show that: (1) in hot and humid environments, wet expansion and thermal expansion happened on concrete, but the deformation is smooth throughout the whole curing age. (2) In hot and dry environments, the concrete suffers from shrinkage. The deformation obeys linear relationship with the natural logarithm of curing age in the first 28 days, and it becomes stable after the $28^{th}$ day. (3) The shrinkage of concrete in a hot and dry environment can be inhibited by adding fiber materials especially steel fibers, and it also obeys linear relationship with the natural logarithm of curing age before it becomes stable. However, compared with no-fiber condition, it takes 14 days, half of 28 days, to make the shrinkage become stable, and the shrinkage ratio of concrete at 180-day age decreases by 63.2% as well. (4) According to submicroscopic and microscopic analysis, there is great bond strength at the interface between steel fiber and concrete. The fiber meshes are formed in concrete by disorderly distributed fibers, which not only can effectively restrain the shrinkage, but also prevent the micro and macro cracks from extending.

• International Journal of Aeronautical and Space Sciences
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• 제14권1호
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• pp.11-18
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• 2013

Human spaceflight experience in extra-vehicular activity (EVA) is limited to two regimes: the micro-gravity environment of Earth orbit, and the lunar surface environment at one-sixth of Earth's gravity. Future human missions to low-gravity bodies, including asteroids, comets, and the moons of Mars, will require EVA techniques that are beyond the current experience base. In order to develop robust approaches for exploring these small bodies, the dynamics associated with human exploration on low-gravity surface must be characterized. This paper examines the translational and rotational motion of an astronaut on the surface of a small body, and it is shown that the low-gravity environment will pose challenges to the surface mobility of an astronaut, unless new tools and EVA techniques are developed. Possibilities for addressing these challenges are explored, and utilization of the International Space Station to test operational concepts and hardware in preparation for a low-gravity surface EVA is discussed.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 추계학술대회 논문집
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• pp.286-290
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• 2001

This paper presents a full-digital low-level controller for a robotic material transfer system which has been developed for a computer-integrated manufacturing model plant. Compared to conventional analog or hybrid type controllers in current industrial environments, this controller system has some advantages such as strong noise-immunity, easy control algorithm implementation, etc The servo-controller consists of two modules, a position controller and a DC servo motor driver. The position controller operates position feedback routines by receiving position encoder data and sending control outputs to the driver. The position controller is implemented in a full-digital way using a recently introduced microcontroller. The DC servomotor driver controls speeds and torques. The driver consists of a micro-controller and insulated-gate-bipolar-transistors (IGBT). The micro-controller provides control signals, and the IGBT's amplifies the control signals and sends them to the motor.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1401-1403
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• 2008

Considering that human body is continuously experiencing mechanical stimuli due to daily activities, the micro-physical environments of cells/tissues should be considered for the successful outcomes in tissue engineering and/or related researches. Obviously, there are many factors involved in cell-based researches. In this presentation, the current trends and some of outcomes are introduced. Through this studies, the roles of mechanical engineering in relation to medical/biological researches are to be emphasized.

• 농업과학연구
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• 제17권1호
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• pp.18-25
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• 1990

The above results indicate that vegetable crop production using vinyl houses continously increases. However, technical support and facility improvement are still insufficent to establish a full production system. In order to improve the cultural environment in facilities for better vegetable culture, several facters should be considered. 1. Facility design and arrangement should be made to improve micro-environments for crop growth and development because direction of facility and covering materials can affect the amount of light trasmitted into vinyl houses. 2. Cultivation of several leading varieties in each crop may not provide stable production and profit especially under undesirable environmental conditions. Thus, it is required to grow not only leading varieties but also other cultivars to decrease the economic losses. 3. Crops should be carefully managed when planted in early season not to experience low temperatures which induce growth retards. Early season cultivation requires proper selection of cultivars which are resistant to low temperture. 4. Active control of micro-environment in facilities should be made via improving the ventilation and irrigation systems.