High-Performance Magnetorheological Suspensions of Pickering-Emulsion-Polymerized Polystyrene/Fe₃O₄ Particles with Enhanced Stability

Han, Sangsuk,Choi, Junsok,Seo, Youngwook P.,Park, In Jun,Choi, Hyoung Jin,Seo, Yongsok American Chemical Society 2018 Langmuir Vol.34 No.8

<P>The magnetorheological (MR) performance of suspensions based on core–shell-structured foamed polystyrene (PSF)/Fe<SUB>3</SUB>O<SUB>4</SUB> particles was investigated by using a vibrating sample magnetometer and a rotational rheometer. Core–shell-structured polystyrene (PS)/Fe<SUB>3</SUB>O<SUB>4</SUB> was synthesized by using the Pickering-emulsion polymerization method in which Fe<SUB>3</SUB>O<SUB>4</SUB> nanoparticles were added as a solid surfactant. Foaming the PS core in PS/Fe<SUB>3</SUB>O<SUB>4</SUB> particles was carried out by using a supercritical carbon dioxide (scCO<SUB>2</SUB>) fluid. The density was measured by a pycnometer. The densities of PS/Fe<SUB>3</SUB>O<SUB>4</SUB> and PSF/Fe<SUB>3</SUB>O<SUB>4</SUB> particles were significantly lowered from that of the pure Fe<SUB>3</SUB>O<SUB>4</SUB> particle after Pickering-emulsion polymerization and foaming treatment. All tested suspensions displayed similar MR behaviors but different yield strengths. The important parameter that determined the MR performance was not the particle density but rather the surface density of Fe<SUB>3</SUB>O<SUB>4</SUB> on the PS core surface. The morphology was observed by scanning electron microscopy and transmission electron microscopy. Most Fe<SUB>3</SUB>O<SUB>4</SUB> particles stayed on the surface of PS/Fe<SUB>3</SUB>O<SUB>4</SUB> particles, making the surface topology bumpy and rough, which decreased the particle sedimentation velocity. Finally, Turbiscan apparatus was used to examine the sedimentation properties of different particle suspensions. The suspensions of PS/Fe<SUB>3</SUB>O<SUB>4</SUB> and PSF/Fe<SUB>3</SUB>O<SUB>4</SUB> showed remarkably improved stability against sedimentation, much better than the bare Fe<SUB>3</SUB>O<SUB>4</SUB> particle suspension because of the reduced density mismatch between the nanoparticles and the carrier medium as well as the surface topology change.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/langd5/2018/langd5.2018.34.issue-8/acs.langmuir.7b04043/production/images/medium/la-2017-040436_0010.gif'></P>

A research on synthesis of foamed polystyrene / Fe₃O₄ particles

Sangsuk Han,Yongsok Seo 한국고분자학회 2016 한국고분자학회 학술대회 연구논문 초록집 Vol.41 No.2

시가 나오야의 『잿빛 달』 연구

한상숙(Han, SangSuk) 동아시아일본학회 2017 일본문화연구 Vol.0 No.61

시가 나오야는 전후(戰後)에 쓴 『잿빛 달』을 통해 시국에 대한 비판과 전후의 사회적 문제를 공간적 이미지로 전쟁에 대한 자신의 사고를 나타내고 있다. 패전에 대한 상흔과 국민의 허탈감과 무력감을 전차역의 이미지로 표현하고 있었다. 시가 나오야는 지붕 없는 도쿄역이라는 공간으로 도쿄를 상징하며 허탈감을 자아내고 있었고, 전쟁고아가 많이 모이는 우에노역으로 패전의 모습을 보여주고 있었다. 화물과 사람을 실어 나르는 이동 수단인 전차는 물자가 부족한 전시상황에서 더욱 중요한 교통수단이다. 그러므로 전차를 공간적 배경으로 그린 『잿빛 달』은 식량을 구하러 멀리 갈 수밖에 없는 궁핍한 생활을 패전 상황으로 여실히 보여주는 것이라 할 수 있다. 시가는 전차를 타는 사람들의 표정과 옷차림을 통해 패전에 대한 처참함을 나타내었고 이러한 상황을 보고도 책임질 수 없는 사람들의 무력감을 그리고 있었다. 또한 시가는 식량부족이라는 사회적 문제를 제시하며 암울한 패전의 모습을 이미지화하였고 사회를 비판적 시각으로 바라보았다. Shiga Naoya expresses his ideas about war by using a spatial image based on the criticism of the national situation and post-war social problems in his post-war (戰後) novel, Ash Color Moon. He expresses defeatism, national distraction, and feelings of impotence through the image of a tram station, a temporal and spatial image. The author indicates absent-mindedness by portraying Tokyo as the space of the Tokyo station, which has no roof, and showing defeatism as the Ueno station, where many war orphans gathered. Accordingly, Ash Color Moon, which describes a tram as a three-dimensional background, realistically shows the situation of deprivation, when people had to travel far to obtain food. Thus, Shiga held a critical view about society in respect to food problems resulting from the gloomy situation caused by the country’s defeat.

기독교의 “권력”과 충돌하는 신체 -시가나오야(志賀直哉)의 『흐려진 머리(濁った頭) 』를 중심으로-

한상숙 ( Sangsuk Han ),박종명 ( Jongmyung Park ) 건국대학교 교육연구소 2014 교사와 교육(구 교육논집) Vol.33 No.-

본 연구는 시가나오야(志賀直哉)의 초기작품 중의 하나인 『흐려진 머리』와 기독교와의 상관관계를 일본의 근대라는 시점에서 고찰하였다. 메이지(明治)정부이래의 서양의 자유주의적 정치이념과 낭만주의의 영향을 받은 일본의 그 당시 청년들은 자유와 평등이라는 개념을 앞세워 기독교의 규정에 따른 억압에 거부감을 느끼고 있었다. 이러한 근대적 개념을 토대로 『흐려진 머리』의 주인공이 겪게 되는 기독교의 간음죄에 대한 규정과 인간의 본성에 따른 욕구와의 충돌에 대해 살펴보았다. 규정에 따른 기독교의 교권에 대항하는 주인공은 마침내 신체의 억압을 느끼며 자유를 갈구하지만 결국은 벗어날 수 없는 권력에 좌절하여 정신병원에 갈 수밖에 없는 상황에 대해서도 알아보았다. 이처럼 서양열강의 중압감이 컸던 일본의 근대를 바라보는 시가나오야의 시각과 신체와 정신과 권력의 상관관계 속에서의 시가나오야가 지향하는 바에 대해 고찰해보았다. This study investigated correlation between “A Muddled Head”, one of the Shiganaoya`s early works, and Christianity, from the viewpoint of Japanese modern times. Japanese youths of the day, affected by Western liberalistic political belief and romanticism since the Meiji government, were resisting suppression coming from the Christian regulations, emphasizing the concept of freedom and equality. Based on these modern conceptions, this paper examined collision between the Christian regulation of adultery and the desire of human nature gone through by the main character in “A Muddled Head”. It reviewed the situation where the main character resisting religious authority of Christianity following regulations finally longs for freedom, feeling repression of his body, but after all, he has nothing to do but to go to the mental hospital, feeling frustrated by the booked power. Like this, this research considered Shiganaoya`s view of Japanese modern era with heavy oppressive feeling given by the Western powers and what he aimed at in the correlation among body, spirit and power.

외국 관광객을 위한 마이크로웹페이지 기반 모바일 정보 시스템 사례

한상숙(Sangsuk Han),소선섭(Sun Sup So),은성배(Seongbae Eun) 한국IT서비스학회 2016 한국IT서비스학회지 Vol.15 No.1

There are continuos tendencies toward that foreign tourists increase. Since 55% of them visit Korea without data communication for saving the communication costs, they can not utilize a variety of O2O services through QR/NFC/ Beacon. There have been some researches to provide a smart map service based on the micro webpage technology even without data communication. But, they do not suggest how the templates are retrieved into their smart-phones. In this paper, we describe a mobile tourist information system for those who have no data communication. We utilize the micro webpage technology to develop a system for market promotion, shopping goods, and tourist maps. What matters in the micro webpage techniques is that the templates should be already downloaded to the users’ smart phones before using it. The preceeded research did not mention the problem. We suggest a scheme that tourists obtain the tremplates in the information offices on the spot through Wi-Fi. We describe the details of the system, and evaluate the data overhead of templates and the time to be downloaded. We show that the overheads are endurable, which means that the system would be working well.

지각된 과잉자격이 적응성과에 미치는 영향: 혁신행동의 매개효과 및 우호적 선망의 조절효과

오상석(Sangsuk Oh),박오원(Owwon Park),한수진(Su Jin Han) 대한경영학회 2021 大韓經營學會誌 Vol.34 No.10

지각된 과잉자격은 자신의 경험, 지식, 기술 및 능력이 현재 수행하고 있는 직무에서 요구되는 것을 초과한다고 지각할 때 발생한다. 과잉자격으로 인지하는 직원들이 점차적으로 증가하면서 지각된 과잉자격이 직원들의 태도와 행동에 미치는 효과는 매우 중요한 의미를 가진다. 지각된 과잉자격에 대한 기존 연구결과들은 대체적으로 지각된 과잉자격이 직무관련 태도와 행동에 부정적인 영향을 미치는 것으로 보고하고 있다. 그러나 과잉자격으로 인지하는 개인들은 직무수행 능력보다는 동기부여가 결여된 경우가 많기 때문에 자신의 능력을 보여줄 수 있는 행동이나 성과에 대해서는 지각된 과잉자격이 긍정적인 영향을 가질 수 있다고 예상해 볼 수 있다. 이러한 논의에 기반하여 본 연구에서는 지각된 과잉자격이 혁신행동을 통해 적응성과를 높일 수 있음을 분석하였다. 즉, 지각된 과잉자격과 혁신행동간의 관계를 분석하고, 지각된 과잉자격과 적응성과간의 관계에서 혁신행동이 매개효과를 가지는지를 검증하였다. 또한 타인에 대한 우호적 선망이 개인을 동기부여시킬 수 있음을 고려하여 우호적 선망을 과잉자격이 혁신행동을 높이는 상황적 요인으로 제시한 후 우호적 선망의 조절효과를 파악하였다. 공공기관에 근무하는 205명의 공무원을 대상으로 실증 분석한 결과 지각된 과잉자격은 혁신행동과 정(+)의 관계를 보였다. 그리고 혁신행동은 지각된 과잉자격과 적응성과간의 정(+)의 관계를 완전 매개하는 것으로 나타났다. 또한 우호적 선망은 지각된 과잉자격과 혁신행동간의 긍정적 관계를 조절하는 것으로 나타났다. 즉, 우호적 선망이 높을수록 지각된 과잉자격과 혁신행동간의 긍정적 관계는 더욱 강화되는 것을 확인하였다. 특히, 지각된 과잉자격과 혁신행동간의 긍정적 관계는 우호적 선망이 높을 때만 유의하고 낮을 때는 유의하지 않은 것으로 나타났다. 마지막으로 본 연구의 이론적, 실무적 시사점 및 후속 연구방향에 대해서 기술하였다. 특히, 실무적 시사점에서는 조직 내에서 지각된 과잉자격에 대한 긍정적 측면이 강조될 필요가 있고, 이러한 긍정적 효과를 촉진하기 위해서 조직 및 관리자들이 관심을 가지고 노력해야 함을 강조하였다. Perceived overqualification occurs when one perceives that one’s experience, knowledge, skills and abilities exceed those required for the job being performed. As the number of employees who are perceived as overqualified gradually increases, the effect of perceived overqualification on the attitudes and behaviors of employees is significantly important. Previous research on perceived overqualification generally identified that perceived overqualification has a negative effect on job-related attitudes and behaviors. However, considering that individuals perceived as overqualification often lack motivation rather than ability, it can be expected that perceived overqualification can have a positive effect on behaviors or job performance that can demonstrate their job abilities. Based on these arguments, this study analyzed that perceived overqualification can enhance adaptive performance through innovative behavior. More specifically, we examined the relationship between perceived overqualification and innovative behavior, and whether innovative behavior had a mediating effect on the relationship between perceived overqualification and adaptive performance. In addition, considering that benign envy toward others can motivate individuals, benign envy was proposed as a contextual factor on the relationship between perceived overqualification and innovative behavior, and then investigated the moderating effect of benign envy. The figure below presents the research model of our study. 〈그림은 본문 참조〉 As a result of empirical analysis of 205 public officials working in public institutions, perceived overqualification showed a significant positive relationship with innovative behavior. And it was found that innovative behavior fully mediated the positive relationship between perceived overqualification and adaptive performance. Also, benign envy played a moderating role of the positive relationship between perceived overqualification and innovative behavior. In other words, the positive relationship between perceived overqualification and innovative behavior was strengthened when benign envy was high rather than low. In particular, the positive relationship between perceived overqualification and innovative behavior was found to be significant only when benign envy was high and not significant when it was low. Finally, the theoretical and practical implications of this study and the suggestions of future research are discussed. In particular, in the practical implications, this study highlighted that organizations paid attention to the positive aspects of perceived overqualification and emphasized that organizations and managers should pay attention and make efforts to promote the positive effects of perceived overqualification.

Next Generation Manufacturing Environment : Ubiquitous Factory

Sangjin Han,Hyunwoong Park,Min Hong,Euijae Kim,Taeho Yang,Sangsuk Lee,Sungjae Lee,Seyol Yang 한국IT서비스학회 2010 한국IT서비스학회 학술대회 논문집 Vol.2010 No.9

Over the past few decades, manufacturing factories have undertaken massive improvements. Early attempts at introducing information technology in manufacturing factories were mainly based on improvements of processes and systems with the purpose of enhancing productivity, quality, and cost reduction. A survey was carried out at a manufacturing company for a purpose of establishing direction of development for technology and services through deduction of current problems and required improvements. As a result, a total of 173 problems were deduced and fundamental causes of the problems were revealed. Ubiquitous factory is a concept of future manufacturing factory in which human's endeavors and technologies are harmoniously interwoven. In this paper, we proposed three element of ubiquitous factory concept; intelligent support, instinctive interaction and ability-sharing.

Allergenic potential and enzymatic resistance of buckwheat

Sujin Lee,Youngshin Han,Jeong-Ryong Do,Sangsuk Oh 한국영양학회 2013 Nutrition Research and Practice Vol.7 No.1

Buckwheat is known as a health food but is one of the major food allergens triggering potentially fatal anaphylaxis in Asia, especially in Japan and Korea. This study was conducted to investigate the characteristic of enzymatic resistance of buckwheat protein and allergenic potential. Enzymatic resistance of buckwheat protein was performed with in vitro digestibility test in simulated gastric fluid (SGF), pH 1.2, using pepsin and simulated intestinal fluid (SIF) using chymotrypsin. Reactivity of buckwheat proteins to human IgE was performed using six allergic patients sensitized to buckwheat. Buckwheat’s IgE levels were measured using the Phadia UniCAP-system. Buckwheat protein, 16 kDa, still remained after 30 min treatment of pepsin on SDS-PAGE. Even though 16 kDa almost disappeared after 60 min treatment, two out of the six buckwheat patients’ sera showed reactivity to hydrolysate after 60 min treatment, indicating that allergenicity still remained. In simulated intestinal fluid (SIF) using chymotrypsin, buckwheat protein, 24 kDa, showed resistance to hydrolysis with chymotrypsin on SDS-PAGE, and still had allergenicity based on the result of ELISA. Our results suggest that buckwheat proteins have strong resistance to enzyme degradation. This may be attributed in part to the allergenic potential of buckwheat. Further study should be continued regarding buckwheat allergy.

지지조건에 따른 반도체 센서 배선의 강도 평가

심재준,이성욱,한동섭,김태형,이상석,한근조 東亞大學校 大學院 2005 大學院論文集 Vol.30 No.-

MEMS structures generally have been fabricated using surface-machining method, but the interface failure between silicon substrate and evaporated thin film frequently was taken place due to the residual stress induced by the fluctuated thermal loads. Therefore this paper studied the residual stress caused the thermal loads in the thin film and introduce the simple method to measure the trend of the residual stress by the indentation. Specimens were made from varialde materials such as Al, Au and Cu and thermal load was applied repeatedly. The residual stress was measured by Finite Element Analysis and the existence of the residual stress due to thermal load was verified by the experimental results. The indentation length of the thermal loaded specimens increased maximum 15% comparing with the virgin thin film caused by tensile residual stress. The finite element analysis results are similar to indentation test.

저손실 자성체에서 정자표면파 전파특성

김명수(Kim Meyngsoo),한기평(Han Geepyeong),김약연(Kim Yarkyeon),이창화(Lee Changhwa),전동석(Dongsuk Jun),이상석(Lee Sangsuk) 대한전자공학회 1998 대한전자공학회 학술대회 Vol.1998 No.11