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소형 지게차의 Idle 진동 저감을 위한 차체 구조 최적 설계
이원태(Wontae Lee),김영현(Younghyun Kim) 한국소음진동공학회 2014 한국소음진동공학회 학술대회논문집 Vol.2014 No.10
A diesel forklift truck under 3-ton class has disadvantages in the vibration transmission path. Because the weight ratio of body structure to powertrain which is source of excitation force is lower th an a midclass forklift. In addition, the torsional and bending vibration mode frequencies of body structure are within the engine excitation frequency range, then high idle vibration generated by resonance. In this paper vehicle body structure design and optimization technique considering idle vibration reduction are presented. Design sensitivity analysis is applied to search the sensitive of design parameters in body structure. The design parameters such as thickness and pillar cross section were optimized to increase the torsional and bending vibration mode frequencies.
화학침전을 이용한 발효액의 젖산 회수 및 유기물 특성분석
이원태(Wontae Lee) 유기성자원학회 2018 유기물자원화 Vol.26 No.1
유기성 폐기물 소화공정의 발효액에서 젖산(lactic acid)을 회수하기 위해 화학침전법을 평가하였다. 젖산(lactic acid)의 회수율을 높이기 위하여 화학침전제 종류와 교반속도 및 침전시간 등 반응조건이 회수율 향상에 미치는 영향을 살펴보았다. 화학침전제의 종류에 관계없이 주입양이 증가할수록 젖산(lactic acid) 회수율 이 증가하는 경향을 보였으며, CaO가 Ca(OH)2와 CaCO3에 비하여 높은 회수율을 나타냈다. CaO를 사용한 반응조건 최적화 실험결과, 교반속도 180 rpm, 침전시간 24 h, ethanol 주입량 25%(v/v)에서 회수율이 48%로 가장 높게 나타났다. 본 연구에서는 발효액 내 젖산(lactic acid)의 농도만 고려하여 주입할 침전제의 양을 계산하였기 때문에 실제 적용을 위해서는 발효액의 유기산 종류 및 농도를 고려하여 침전제의 투입량을 결정해야할 것이다. 유기물의 정성적 분석(FEEM, SEC) 결과로 볼 때 침전공정은 유기산의 특성에 큰 영향을 미치지 않았다. Recovery of lactic acid from fermentation broth using chemical precipitation was investigated with various chemicals. Effects of chemical types, mixing speeds, settling duration, and solvent addition were evaluated to improve the recovery rates of lactic acid. Overall, recovery efficiencies increased as the dosage of chemicals increased. Recovery rate of lactic acid by CaO was higher than those of Ca(OH)2 and CaCO3. Recovery of lactic acid increased by 48% under the optimized reaction conditions which included a mixing speed at 180 rpm, a settling duration of 24 h, and addition of ethanol at 25%(v/v). Practical application needs to consider types and concentrations of other organic acids as well as lactic acid. Based upon the results of fluorescence excitation emission matrix (FEEM), size exclusion chromatography (SEC), characteristics of recovered lactic acid were same as that in the fermentation broth.
이원태(Wontae Lee),민희(Min Hee) 21세기정치학회 2015 21세기 정치학회보 Vol.25 No.1
This study aims at identifying the changes in conflict structure in Korean society caused by the evolution of the digital media platform, analyzing the newly arising social and cultural conflict issues with the spread of social media such as Twitter. This study carried out an analysis on the new aspects and issues of social conflicts caused by the evolution of digital media based on a theoretical and historical review of the conflict structure in Korean society. This paper suggested that online social conflict was defined in consideration of its various aspects and complexity, especially online conflict is basically defined as a 'communication conflict'. In this fast changing digital environment, it is ever more important to analyze new social conflicts from a new perspective. In other words, the social conflict paradigm is shifting from 'industrial-type conflict' centered on data inequality to the 'digital conflict' with complex and multilateral structures covering technology, culture and generations. It is expected that the result of this study will contribute to reaching the positive perception of online social conflicts.
이원태(Wontae Lee) 21세기정치학회 2013 21세기 정치학회보 Vol.23 No.2
This study looks into the mobile divide and political participation divide which get complicated with the introduction and spread of smartphone, beyond the previous studies on the information divide and digital divide in PC-based Internet environment. The mobile divide affects not only the users' access to and use of information and Internet but also the quality of participation, which means that a widening mobile divide might bring inequality in political or social engagement. In this regard, the purpose of this study is to figure out how to lay a foundation for supporting all Koreans to become a 'Digital Citizen' who freely uses smart devices and services by narrowing the mobile political divide. And this study presents a policy direction for narrowing the ‘mobile participation divide’ with theoretical conceptualization. The mobile participation divide is expected to emerge as an important part in the digital divide and how to close the mobile divide will become a critical social issue. Although efforts are being made in Korea to develop the next-generation digital divide indexes and comprehensively evaluate the current digital divide, an independent participation divide index, which reflects the nature of the mobile environment, needs to be developed.
소셜미디어 유력자의 네트워크 특성 : 한국의 트위터 공동체를 중심으로
이원태(Wontae Lee),차미영(Meeyoung Cha),양해륜(Haeryun Yang) 서울대학교 언론정보연구소 2011 언론정보연구 Vol.48 No.2
본 연구는 최근 트위터와 같은 소셜미디어에서 의제설정, 여론형성 등에 큰 영향력을 발휘하고 있는 새로운 유형의 오피니언 리더, 즉 소셜미디어 유력자들(social media influentials)의 네트워크 특성과 역할을 규명하는 것을 목적으로 한다. 연구결과 한국의 트위터 유력자들은 글로벌 네트워크와는 달리 이용자 상호작용(user interaction)의 측면에서 매우 강력한 네트워크 호혜성을 특징적으로 보여주고 있으며, 이들 트위터 유력자의 영향력도 그들이 보유한 팔로어 규모에 의존하기보다는 적극적인 리트윗(RT)을 매개로 하는 수많은 팔로어들과의 개방적 소통방식에 의해 적극 추동된다는 점을 보여주었다. 특히 ‘매개적 유력자(intermediary influentials)’의 역할에서 보듯이, 강력한 유력자 네트워크의 이면에는 네트워크 구성원들의 추천과 평판에 기반한 쌍방향적인 의사소통이 놓여 있음을 알 수 있다 This study aims to shed light on the network property and roles of social media influentials who are emerging as a new type of opinion leaders in setting the agenda and forming public opinions on online social networking sites such as Twitter. The result shows that the Korean Twitter influentials exhibit very strong reciprocity in terms of topology and user interaction. Their impact on other users relies more on open communication with followers via retweeting (RT) than on how many followers they have. In particular, beneath the surface of the powerful influentials network, intermediary influentials engage in interactive communications with the network members based on peer recommendation and reputation.