• 공업화학
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• 제17권1호
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• pp.12-15
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• 2006

본 연구의 목적은 물유리에 의해 제조된 실리카 미립자의 평균입도와 입도분포에 미치는 반응조건, 용매 및 계면활성제의 영향을 조사하는 것이다. 실리카 미립자는 다양한 종류의 계면활성제와 분산용매를 사용하는 에멀젼법에 의해 제조하였다. 계면활성제로는 비이온성인 Span 20, Span 40, Span 60 및 Span 80을 사용하였으며, 분산용매로는 알킬그룹인 n-Hexane, n-Heptane, iso-Octane 및 n-Decane을 사용하였다. 실험결과에 의하면 유화교반속도에 따른 실리카 미립자의 평균 입경은 교반속도가 증가함에 따라 감소하였으며, 일정한 입경의 에멀젼을 형성하기 위한 최적의 유화교반시간은 약 6 min임을 알 수 있었다. 생성된 실리카 미립자의 평균입경은 사용된 용매의 분자량이 증가함에 따라 감소하며, 사용한 계면활성제의 hydrophobic lipophilic balance(HLB) 값이 감소함에 따라 증가하였다.

• Journal of Pharmaceutical Investigation
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• 제12권2호
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• pp.31-36
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• 1982

The effect of some surfactants, such as tween 40, tween 80, span 80, and triethanolamine, on the absorption of lidocaine was studied using goldfish as a model of absorption kinetics. This model was believed that reciprocal overturn time and death time were the occurrence of biological effect versus drug absorption. The results were as follows; The threshold concentration of lidocaine was significantly reduced by the surfactants. Overturn time and death time of goldfish in the lidocaine solution were reduced by such surfactants as tween 40, tween 80, span 80 and triethanolamine, and more reduced with increasing concentration of surfactants except tween 40 and tween 80. The plots of reciprocal death time versus lidocaine concentration were linear relationship with a positive concentration intercept such as minimum effective concentration (0.2-0.8%). As results it is believed that these surfactants may form complexes with lidocaine or affect the goldfish membrane to make more permeable to lidocaine, which is adsorbed more rapidly.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.1452-1459
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• 2010

Application of long-span bridge, which is affected by parameters such as span length, shoe boundary condition, track property and stiffness of superstructure and substructure etc., can vary. Especially, by CWR aspects of the axial force, that can be less constraints of construction depending on whether the application of rail expansion joint(REJ), which has disadvantaged in terms of maintenance. In this study, it was performed parameter study for multiple variables (shaft length, the upper and lower cross-section characteristics, track characteristics, etc.) in terms of CWR aspects. Structure-rail interaction analysis was applied to the typical simple span PSC Box and 3 span continuous bridge Extradosed Bridge(50m+80m+50m) excluding REJ. If you set the boundary e of variables for long-span railway bridge excluding REJ through the this study, when designing future is expected to be able to useful.

• 대한토목학회논문집
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• 제3권3호
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• pp.39-51
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• 1983

강항(鋼桁)의 내하력부족(耐荷力不足)을 강재(鋼材)를 사용(使用)한 개판(蓋鈑) 또는 부재(部材)로서 보강(補强)하였던 것이 종래(從來)의 공법(工法)이며 이것도 대부분(大部分) 단순항(單純桁)에 한정(限定)되었었다. 본(本) 연구(硏究)에서 단순항(單純桁) 뿐만 아니라 2경간(徑間), 3경간연속(徑間連續)도 고인장강(高引張鋼)(P.C 강선(鋼線))으로 per-stress하여 단부정착(端部碇着)한 보강재(補强材)로 내하력(耐荷力)의 증대(增大)를 현저(顯著)하게 보았다. 장차(將次)의 하중증대(荷重增大)를 고려(考慮)하여 강항제작당시(鋼桁製作當時)에 보강장치(補强裝置)를 미리 설치하여 현장가설(現場架設) 때 pre-stressing하여 정착(碇着)시켜 놓면 목적(目的)은 달성(達成)된다. 이렇게 하면 단순항(單純桁), 2경간(徑間), 3경간연속항(徑間連續桁)이 최소(最小) 80%이상(以上) 내하력증가(耐荷力增加)가 되고 전경간(全徑間) 등분분포하중(等分布荷重)이 만재(滿載)될 때는 2경간연속(徑間連續) 단순항(單純桁)에서 약(約) 100%의 내하력증가(耐荷力增加)가 허용(許容)된다.

• 한국강구조학회 논문집
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• 제14권2호
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• pp.319-327
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• 2002

강재의 고강도화 및 경량화가 실현되고, 해석기법이 발달함에 따라 장경간을 갖는 강아치교의 건설이 가능하게 되었다. 장경간 아치교를 설계하기 위해서 경제적으로는 재료를 최소화시키며 구조적으로는 안전해야 한다. 이에 본 연구의 목적은 최적설계를 위한 형고의 높이를 제시하고 강재량에 영향을 주는 라이즈-경간비에 대해서 우리나라 활하중을 재하하여 검토하였다. 또한 구조적 안전성을 검토하기 위해 지진에 대한 동적거동을 비교 연구하였다. 라이즈-ㄱ경간-형고에 대한 관계식은 60, 70, 80, 90, 100m의 5개 기본경간을 SAP2000 프로그램을 이용하여 값을 산출하고 회귀분석을 통하여 관계식을 얻었다. 그리고 지진에 대한 동적 거동을 파악하기 위해 포트받침과 탄성받침을 사용했을때 교각형태, 교각높이 및 라이즈-경간비등을 변화시켜 교축방향과 교축직각방향에 대한 단면력을 확인하였다.

• 공업화학
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• 제8권4호
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• pp.551-559
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• 1997

유화형 액막을 이용하여 $D_2EHPA-Kerosene-Span$ $80-H_2SO_4$계에서 Zn 성분의 추출시 액막의 안정성에 영향을 미치는 에멀젼의 파괴, swelling 현상 및 에멀젼의 morphology를 조사하였다. Zn 성분의 추출시 액막의 안정성에 대한 최적 조건은 계면활성제 Span 80의 농도 2~3 vol.%, 추출담제 $D_2EHPA$의 농도 5~7 vol.%, 막강화제 paraffin oil의 농도 10 vol.% 였으며, 외부수용액에 대한 에멀젼의 비 0.1, 유기상에 대한 내부수용액의 비는 1.0이 적절하였다.

• 대한인간공학회지
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• 제33권6호
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• pp.553-563
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• 2014

Objective: The purpose of this study was to evaluate the effect of gender (male, female) and grip spans (45, 50, 60, 70, 80mm) on total grip strength, resultant force, finger force and subjective discomfort rating. Background: In order to prevent musculoskeletal disorders, studies of hand tools need to be preceded based on grip strength, finger force, and subjective discomfort rating. However, experimental apparatus using tools such as pliers that reflect the actual work place was almost non-existent. Method: Fifty-Two (26 males and 26 females) participants were recruited from the student population. In this study, a pair of revised pliers, which can change grip span from 45 to 80mm was applied to estimate total grip strength, resultant force and individual finger forces. All participants were asked to exert a maximum grip force with three repetitions, and to report the subjective discomfort rating for five grip spans of pliers (45, 50, 60, 70, 80mm). Results: There were significant differences of total grip strength, resultant force, individual finger forces and subjective discomfort rating according to grip span. The lowest total grip strength was obtained from the grip span of 80mm for both genders. For resultant force, the highest resultant force was exerted at grip spans of 50, 60 and 70mm for females and 50 and 60mm for males. The lowest subjective discomfort rating was observed in the 50mm for both genders. Conclusion: Based on the result, 50mm and 60mm grip spans which provide the highest force and lowest discomfort rating might be recommendable for the male and female pliers users. Application: The findings of this study can provide guidelines on designing a hand tool to help to reduce hand-related musculoskeletal disorders and obtain better performance.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.1691-1696
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• 2010

Jeong-Ji overbridge is designed to be 9.3km long, the longest for a high speed railway bridge ever constructed in Korea. This bridge is constituted of three types of structure. Standard type bridge is 35m PSC Box bridge which will be constructed by Precast Span Method. To cross the Cheonan Nonsan Expressway, 80m three-span steel arch bridge is designed to avoid rail expansion joint. Finally, Extradosed bridge is planned for high speed railway bridge for the first time in Korea based on originative and advanced design techniques. It is expected that this will contribute to the development of national technology for long-span high speed railway bridges.

• 한국가축번식학회지
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• 제22권1호
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• pp.89-94
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• 1998

A study was made to investigate the effects of concerning factors with IGF-I recovery on the final IGF-I concentration in the effluent and to establish recovery conditions of IGF-I using liquid emulsion membranes(LEM). D2EHPA was best carrier among Amberlite LA2, Aliquit 336 and D2EHPA for recovery rate of IGF-I. Recovery rate of IGF-I by D2EHPA volume in the oil phase was increased as increasing D2EHPA volume, and optimal volume of D2EHPA was 5% in this experiment. The recovery rate of IGF-I by D2EHPA was increased by the decreasing from pH 7 to pH 4 of external phase. Therefore, optimal pH value was 4.0. Optimal concentrations of sulfuric acid in internal phase, paraffin oil in oil phase and Span 80 for recovery rate of IGF-I were 0.1M, 2.0% and 5%, respectively, and optimal W/O rate was 2. These results suggested that optimal conditions for recovery of IGF-I were D2EHPA(5%) as carrier, pH 4.0, 0.1M sulfuric acid, 2% paraffin oil, 2.0 W/O rate and 5.0% Span 80.

• 대한인간공학회지
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• 제32권6호
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• pp.511-516
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• 2013

Objective: The objective of this study is designing an optimal hand tool through maximum grip force study accordance to the hand grip span. Background: In order to prevent musculoskeletal diseases, studies on hand tool design are proceeding based on grip strength, finger force, and contribution of individual finger force on total grip strength. However, experimental apparatus using a tool that is actually used in work place was almost non-existent. Method: 19 males were participated in an experiment. Using the load cell inserted real plier, finger force, grip strength, and subjective discomfort rate of both hands (dominant and non-dominant) were measured in 5 different hand grip span(45mm, 50mm, 60mm, 70mm, and 80mm). Results: There was significant difference(p<0.001) of total grip strength, individual finger force and subjective discomfort rating according to various hand grip span(45, 50, 60, 70, and 80mm). Also, statistically significant different(p<0.001) was shown between the dominant hand and non-dominant hand. In addition, individual finger force in maximum grip was in order of middle finger, ring finger, index finger, and little finger. Conclusion: Optimal grip span of pliers that exerting maximum grip strength is 50~60mm. Application: This finding is expected to be used for designing proper pliers.