• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.793-799
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• 2011

A comprehensive analysis of wheel force spectrum is conducted to provide the KTX safety evaluation with structural behaviour of Pre-Stressed Concrete (PSC) box bridge due to various high speeds. The wheel spectrum for KTX locomotive running over road and PSC bridge tracks is compared using irregular track responses with numerical models of 170m approach road track and 40m span length of PSC box bridge The high-speed railway locomotive is used as 38-degree of freedom system. Three displacements (vertical, lateral, and longitudinal) and three rotational components (pitching, rolling, and yawing) for one car-body and two bogies are considered in the 38-degree of freedom model. Three dimensional frame element of finite element method (FEM) is used to model of the simply supported PSC box bridge. The irregulation of rail-way is derived using the experiential spectrum density function under assumption of twelve level tracks conditions based on the normal probability procedure. The dynamic analyses by Runge-Kutta method which are able to analyze the high frequency wheel force spectrum. A dynamic behaviour of KTX due to high speeds until 450km/h developing speed with relative time is analysed and compared the characteristics running over the road and PSC box bridge tracks. Finally, the KTX integrated evaluation method of safety between high speed train and bridge is presented.

• 한국항행학회논문지
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• 제5권1호
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• pp.11-18
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• 2001

본 논문에서는 주파수 선택성 레일리 페이딩 통신로에서 주파수 호핑 패턴의 히트를 고려한 Orthogonal MC/FH-CDMA 통신 방식의 BER 성능을 평가하였고, TCM 기법을 적용하여 성능 개선 정도를 도출하였다. 성능 해석 결과, 캐리어 슬롯 수가 증가하면 심볼 시간에 대해 지연 시간차가 적어지기 때문에 오율 특성이 개선됨을 알 수 있었다. 그리고 호핑 패턴의 히트 때문에 큰 에러가 발생하고, 이 때문에 사용 캐리어 수를 많게 할 수 없어 직교화의 효과가 낮아짐을 알 수 있었다. 한편, TCM 기법을 적용하면 BER 성능이 약 $5{\times}10^{-2}$정도 개선됨을 알 수 있었고, 음성 QoS 조건 (BER = $10^{-3}$)을 만족시키기 위해서는 더욱 더 큰 S/N 비가 요구됨을 알 수 있었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.382-382
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• 2012

Nanostructures have a larger surface/volume ratio as well as unique mechanical, physical, chemical properties compared to existing bulk materials. Materials for biomedical implants require a good biocompatibility to provide a rapid recovery following surgical procedure and a stabilization of the region where the implants have been inserted. The biocompatibility is evaluated by the degree of the interaction between the implant materials and the cells around the implants. Recent researches on this topic focus on utilizing the characteristics of the nanostructures to improve the biocompatibility. Several studies suggest that the degree of the interaction is varied by the relative size of the nanostructures and cells, and the morphology of the surface of the implant [1, 2]. In this paper, we fabricate the nanowires on the Ti substrate for better biocompatible implants and other biomedical applications such as artificial internal organ, tissue engineered biomaterials, or implantable nano-medical devices. Nanowires are fabricated with two methods: first, nanowire arrays are patterned on the surface using e-beam lithography. Then, the nanowires are further defined with deep reactive ion etching (RIE). The other method is self-assembly based on vapor-liquid-solid (VLS) mechanism using Sn as metal-catalyst. Sn nanoparticle solutions are used in various concentrations to fabricate the nanowires with different pitches. Fabricated nanowries are characterized using scanning electron microscopy (SEM), x-ray diffraction (XRD), and high resolution transmission electron microscopy (TEM). Tthe biocompatibility of the nanowires will further be investigated.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2015년도 추계 학술논문 발표대회
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• pp.151-152
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• 2015

Concrete parking slab is often deteriorated severely after winter season because of concrete's freezing and thawing phenomenon. In this study, some methods to improve resistance against freezing-thawing is experimentally tested.: 1) concrete strength, 2) air content in concrete, 3) saw-cut effect and finish material. After experiment, in case of no finishes, 24MPa concrete with 4% air content is tested best result in terms of relative elastics modulus among testes ones. In case of concrete with finishes, all specimens are improved regardless of finishes compared to concrete with no finishes. Improvement degree compared to no finish is as follows : Polyurea > Resin-mortar > hardener and the number of improvement degree is 5, 4, 2% respectively. Further work is required considering construction site condition such as gaining water on surface and remicon in order to reflect site condition.

• 동아시아식생활학회지
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• 제7권4호
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• pp.519-526
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• 1997

Propylene oxide와 반응시켜 치환도가 0-0.2645되는 하이드록시프로필화 감자 전분을 제조하여 이화학적 성질들을 측정하였다. 전분의 하이드록시프로필기 함량은 propylene oxide의 농도에 비례하였다. 하이드록시프로필화 감자 전분의 물결합력은 치환도가 증가할수록 증가하였고 pH는 치환도가 증가할수록 감소하였다. 청가와 요오드 흡착 강도는 치환도가 증가할수록 감소하였다. 시차주사열량계에 의한 호화양상에서는 하이드록시프로필화에 의해 전분의 호화온도가 낮아지는 것으로 나타났다. 하이드록시프로필화에 의해 전분의 상대 결정 화도는 낮아졌고, 전분 입자가 파괴되었음이 X-선 회절도와 주사전자현미경으로 각각 관찰되었다. 이것은 고농도의 하이드록시프로필화가 전분의 무정형 부분뿐만 아니라 결정성 영역에까지 영향을 주었음을 의미하였다.

• 한국의류학회지
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• 제22권1호
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• pp.116-126
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• 1998

This study was conducted to examine the effect of difference in materials of aerobic wear on both human body's physiological reactions and subjective wearing sensation by comparing and analysing not only cotton sparidex A, B and C but nylon spandex D, E and F used as actually wearing materials. The rectal temperature of type A and I remained at high degree, the type C was higher from after high-speed running but dropped sharply when taking a break finally. Both skin temperature and mean skin temperature dropped sharply due to sweat occurred during physical exercise, and then rose slowly when taking a break. Type A -D and B-I showed that the mean skin temperature remained at high degree when wearing a cotton spandex. Type C's temperature within its aerobic wear was lower than type F while its relative humidity was higher than type F. Wearing sensation showed a change similar to wearing, particularly, which was remarkable in type B-E. Also, it was shown that humidity sensation, tactile sensation and comfort sensation were good when wearing the cotton spandex.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.599-602
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• 2005

This paper describes a experimental study determining the effects of the type and loudness of introducing sounds on the amenity and the masking degree of background noise. 132 relative test sounds with 11 types of introducing sounds and 3 steps of road traffic noise were presented to 29 subjects through headphone in the laboratory experiment. Seven scale of polar adjective such as 'Strong Weak', 'Pleasant Unpleasant', 'Clear Unclear', 'Suitable Unsuitable', 'Comfortable-Discomfortable' was employed for the evaluation of amenity. And Seven scale of mono polar adjective such as 'Very-Not at all' was employed for the evaluation of masking degree against road traffic noise. The results are as follows; Green music was evaluated the highest amenity among test sounds and murmurs of a stream, signal music, song of a bird, crying of insect was showed the amenity rank of order. The softer and weaker introducing sound was evaluated more suitable and comfortable under the road traffic noise. So adequate level of introducing sounds was considered for the desirable urban soundscape. Also the louder sounds compared to background noises had greater masking effects. But similar levels of introducing sounds were recommended considering both good amenity and masking effects.

• 품질경영학회지
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• 제46권3호
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• pp.717-738
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• 2018

Purpose: This study aims to analyze why surveys of a single set of customer requirement result in different Kano analyses depending on the survey questionnaire designs. Methods: This study singled out 14 common features from four different questionnaires of two studies of Smart Car features and analyzed them using the Kano model. Several methods and devices were used: Group Comparison and Timko Index were applied; Kano Distribution Index, Timko Dispersion and Kano Conformity were newly introduced for the quantitative analysis; Correlations between Timko indices from different Kano questionnaires were conducted; Heuristic Splitting technic for reinforcing attribute categorization is introduced. Results: Correlation Coefficient proved strong positive relations among the three questionnaires, whose agreement degree of the resulting Kano attributes showed less than 10% when Indifferent was ignored. Heuristic Splitting on Timko charts enhanced the degree of the resulting Kano attributes up to 80%. Conclusion: Among the questionnaires the representation of customer requirements tends to move by parallel shifts on the Timko chart maintaining their relative locations. Heuristic Splitting suggests a rational solution to the interpretation of those inexplicable attribute categories resulting from traditional Kano methods.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.97-102
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• 2007

As environmental vibration requirements on precision equipments get more stringent, use of pneumatic vibration isolators becomes more crucial and, hence, their dynamic performance needs to be further improved. Dynamic behavior of those pneumatic vibration isolation tables is very important to both manufacturer and customer as performance specifications. Together with conventional transmissibility, transient response characteristics are another critical performance index especially when movements of components, e.g., x-y tables, of the precision equipments are very dynamic. In this paper, analysis on transient response of a pneumatic vibration isolation table loaded by a mass moving on it is presented. This is a conventional dynamics problem on a rigid body with 6 degree of freedom and a mass with another degree of freedom. How to obtain transient responses of the isolation table is described when the movements of the mass are prescribed relative to the table.

• International Journal of Industrial Entomology and Biomaterials
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• 제31권2호
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• pp.35-39
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• 2015

The developmental responses of insects to temperature are important considerations in gaining a better understanding of their ecology and life histories. Temperature-dependent phenology models permit examination of the effects of temperature on the geographical distributions, population dynamics, and management of insects. Measurements of insect developmental and survival responses to temperature pose practical challenges that depend on the chosen modality, variability among individuals, and high mortality rates near the lower and upper threshold temperatures. Different temperature levels can significantly affect larval development of Eurema hecabe. The development of E. hecabe reared on leaves of Lespedeza cuneata was investigated at three temperature regimes (20, 25, and 30℃), a relative humidity of 60%, and a light:dark photoperiod of 14:10 h. The developmental time from larva to adult was 34.3, 20.6, and 17.9 d at temperatures of 20, 25, and 30℃, respectively. Pupal rate was 47.6%, 47.6%, and 61.9% at temperatures of 20, 25, and 30℃, respectively. The developmental threshold temperature estimated from larva to pupae was 8.1℃ with 381.7 degree-days. There is an increasing need for a standardized manual for rearing this butterfly species based on adequate knowledge of its ecology.