Effect of solution pH on the microstructural and rheological properties in boehmite suspensions

이기욱,Kim Seong Hwan,이다영,Lee Kwan-Young,Byoungjin Chun,정현욱 한국유변학회 2023 Korea-Australia rheology journal Vol.35 No.1

The relationship between microstructure changes and rheological properties in suspensions containing boehmite particles, which are well applied in various industrial wash-coating processes, was investigated by changing pH condition. The boehmite particles in suspensions were either well dispersed or aggregated depending on the pH, owing to the relative contributions of repulsive interaction between particles as well as hydrolysis and condensation reactions. Four groups of boehmite suspensions were classifi ed as very low, intermediate, almost zero charge, and high pH regimes based on their colloidal behaviors, and their microstructural diff erences were investigated using transmission electron microscopy (TEM) and multi-speckle diff using wave spectroscopy (MSDWS). For gel-like suspensions of three groups, various rheological properties such as shear viscosity, viscoelastic modulus, yield stress, and recovery behavior were extensively compared, and the results clearly demonstrated that a suspension with high yield stress was not fully recovered into the original state when disturbed at high shear rates.

전자주권제도의 도입에 관한 연구

이기욱,Lee, Ki-Wook 한국디지털정책학회 2009 디지털융복합연구 Vol.7 No.4

Electronic methods are already used in money transfer and credit cards transactions and electronic money and checks, which can substitute cash and coins, are being discussed. Recently, the Acts of Electronic Draft have been enacted, in order to make the money in the market flow efficiently. Also electronic bill of lading has been adopted for the practical use of international shipments. However, despite of the effort from the academia and practice, investments to stocks, especially in the stock exchange, is not quite perfectly electronic. Japan enacted a relevant act in 2004 which make its stock market totally dematerialized. This writing summarizes some issues in interpretation that arise in the course of operation of the Stock Electronic Registration System at the present time of 6 months after it came into effect and its purpose, by doing so, is to prevent in advance the kind of problems in introducing the similar system to Korea.

조건 술어 분석을 이용한 능동규칙의 조건부 처리 시스템

이기욱,김태식,Lee, Gi-Uk,Kim, Tae-Sik 한국정보처리학회 2002 정보처리학회논문지D Vol.9 No.1

능동 데이터베이스 시스템은 특정한 상태를 탐지하는 능동규칙을 도입한다. 조건부 평가는 사건이 발생할 때마다 수행되기 때문에 조건부를 처리하는 방법에 따라 시스템의 성능에 중요한 영향을 미친다. 본 논문에서는 차이트리 구조, 분류트리, 그리고 집계함수 테이블을 생성하는 전처리 기능을 갖는 조건부 처리 시스템을 제안한다. 전처리는 능동규칙을 미리 파악할 수 있는 능동 데이터베이스의 특징 때문에 도입될 수 있다. 본 논문에서는 선택연산, 조인연산, 그리고 집계함수를 효율적으로 처리할 수 있는 차이트리를 제안하고 조건부의 처리 성능을 높인다. 그리고 조인연산을 효과적으로 처리하는 분류트리와 높은 처리비용을 요구하는 집계함수를 처리하는 집계함수 테이블을 제안한다. 본 논문의 조건부 처리 시스템은 전처리 기능에서 만들어진 조건부 처리 구조 때문에 조건 비교의 횟수를 감소시켜 능동규칙에서 조건부 처리의 성능 향상을 기대할 수 있다. The active database system introduces the active rules detecting specified state. As the condition evaluation of the active rules is performed every time an event occurs, the performance of the system has a great influence, depending on the conditions processing method. In this paper, we propose the conditions processing system with the preprocessor which determines the delta tree structure, constructs the classification tree, and generates the aggregate function table. Due to the characteristics of the active database through which the active rules can be comprehended beforehand, the preprocessor can be introduced. In this paper, the delta tree which can effectively process the join, selection operations, and the aggregate function is suggested, and it can enhance the condition evaluation performance. And we propose the classification tree which effectively processes the join operation and the aggregate function table processing the aggregate function which demands high cost. In this paper, the conditions processing system can be expected to enhance the performance of conditions processing in the active rules as the number of conditions comparison decreases because of the structure which is made in the preprocessor.

군사법 제도개혁의 핵심과제

이기욱?(Lee, ki-Wook) 한양법학회 2004 漢陽法學 Vol.15 No.-

SNS 기반 재무관리 앱

이기욱 ( Ki-wuk Lee ),이다희 ( Da-hee Lee ),임진수 ( Jin-su Lim ),정세희 ( Se-hui Jeong ),이성철 ( Sungchul Lee ) 한국정보처리학회 2022 한국정보처리학회 학술대회논문집 Vol.29 No.2

본 앱은 SNS 기능이 탑재된 재무관리 앱으로, 가계부에 전에 없던 SNS 기능을 추가시켜 가계부와 SNS를 동시에 즐길 수 있으며 가계부에 작성한 내용을 공유하여 여러 유저들에게 지식과 정보를 공유할 수 있다.

고출력 환경에 적용 가능한 광대역 다층 구조 레이돔

이기욱(Ki Wook Lee),이경원(Kyung Won Lee),문병귀(Bang Kwi Moon),최삼열(Samyeul Choi),이왕용(Wangyong Lee),윤영중(Young Joong Yoon) 한국전자파학회 2018 한국전자파학회논문지 Vol.29 No.1

고출력 응용환경에 적용 가능한 광대역 다층 구조 레이돔을 개발하였다. 이를 위해 다층 레이돔의 전파전파특성을 ABCD 행렬로 표현하였고, Particle swarm 최적화 알고리즘을 상용 수치 모델링 툴로 구현하여 레이돔의 최적화된 층별 두께와 물질상수를 구하였다. 바람, 눈, 얼음 등 외부 기상 환경을 고려한 기계적 특성을 감안하여 레이돔을 재설계하였다. 대형구조물의 제작 제한조건을 고려한 두께를 재산출하여 전력 전달특성을 재분석하였다. 대기 정전파괴 때보다 10 ㏈ 높은 첨두 전기장의 세기 조건에서 상용 해석 툴을 이용하여, 설계된 레이돔의 RF에 대한 대기 정전파괴 특성을 분석하였다. 설계된 다층 레이돔을 제작하여 소신호 및 대신호 시험을 수행하였고, 상용 도구들을 사용한 계산값과 비교하여 목표 성능을 획득하였다. In this paper, we developed a broadband multi-layered radome applicable for high-power applications. In this regard, we presented the wave propagation characteristics of the broadband multi-layered radome with the ABCD matrix and obtained the optimal thickness and the material constant for each layer by an optimization algorithm called “particle swarm optimization,” implemented by a commercial numerical modeling tool. Further, we redesigned it in view of mechanical properties to reflect environmental conditions such as wind, snow, and ice. The power transmission property was reanalyzed based on the recalculated data of each layer’s thickness to consider the limitations of the fabrication of a large structure. Under the condition of a peak electric field strength that is 10 ㏈ above the critical electric field strength in air breakdown, we analyzed the air breakdown by radio frequency(RF) in the designed radome using the commercial full-wave electromagnetic tool. The radome was manufactured and tested by continuous wave(CW) RF small signal and large signal in an anechoic chamber. The test results showed good agreement with those attained by simulation.

신규변이 탐지 소프트웨어 도구의 비교 분석

이기욱(Ki-Wook Lee),김재원(Jae-Won Kim),황규백(Kyu-Baek Hwang) 한국정보과학회 2015 한국정보과학회 학술발표논문집 Vol.2015 No.6

진공단열체 지지대의 모델링 및 형상 최적화

이기욱(K. W. Lee),조성욱(S. W. Cho),김종민(J.M. Kim),김승욱(S.W. Kim),송태호(T.H. Song) 한국정밀공학회 2011 한국정밀공학회 학술발표대회 논문집 Vol.2011 No.6월

이사의 의무와 성실성

이기욱(Lee, Ki-Wook) 한양법학회 2015 漢陽法學 Vol.26 No.1

Later in 2006, sudden doubts arose not only about the importance of new fiduciary duty, but about whether the duty even existed. In Stone v. Ritter, the Delaware Supreme Court again examined the contours of the fiduciary duty of good faith and announced that it was not a separate duty, but rather part of the traditional duty of loyalty, and that its breach did not alone state a cause of action. Two years later, in Lyondell Chemical Co. v. Ryan, the Delaware Supreme Court seemed to reduce the duty even further. The current absence of agreement among scholars about the scope and relative importance of the doctrine of good faith makes the topic ripe for discussion from varied perspectives, and that is the reason for this symposium. One group of judges and scholars suggested that the importance of focusing on the duty of good faith may be greatly exaggerated. Other scholars, and indeed some of the same scholars when in a different mood, are more optimistic that the doctrine of good faith may still contain substance, and could be important in explaining what senior corporate managers must do: most importantly, that directors’ motives in approving transactions can be scrutinized and that directors must obey positive law, regardless of the possibility of opportunistically making profits. Proponents of managerial accountability in corporate governance look for meaning in the doctrine of good faith because the traditional fiduciary duties of care and loyalty in reality do little to discipline boards. Prior to 1985, corporate directors were virtually never found liable for violating the duty of care unless accompanied by allegations of self-dealing (i.e., duty of loyalty violations). After the stunning decision in Smith v. Van Gorkom in 1985, which held directors liable for monetary damages because they had been grossly negligent in violation of their duty of care, the Delaware legislature promptly overruled the judiciary. Delaware adopted a provision that would allow corporations to adopt charter provisions to exculpate directors for duty of care violations. Most corporations adopted these amendments, and most other state legislatures followed Delaware. Just as exculpation for gross negligence made the duty of care protections trivial, Delaware courts also tended to define self-dealing so narrowly that the duty of loyalty provided minimal protection to corporations and their constituents. Even with self-dealing, it was generally easy to have non-interested directors sanitize otherwise tainted transactions, leaving corporate directors with little meaningful accountability. Given the weakness of traditional remedies, the duty of good faith, whether as one of a triad of fiduciary duties or as part of a more robust duty of loyalty, can be of great importance. As Disney made clear, the duty of good faith cannot be satisfied if directors: act in subjective bad faith; consciously disregard their duties; are motivated by an actual intent to harm the corporation; or cause the corporation to violate positive law. I think this new focus on the motives of directors and the express fiduciary duty to avoid knowing violations of law could be crucial for corporate governance because neither violation is subject to the protections of the business judgment rule or charter exculpation provisions.

영구자석 스탭스큐가 적용된 외전형 IPMSM의 스탭수에 따른 특성 연구

이기욱(Ki Wook Lee),박관수(Gwan Soo Park) 대한전기학회 2014 대한전기학회 학술대회 논문집 Vol.2014 No.7