• Journal of the Korean Chemical Society
• /
• v.46 no.3
• /
• pp.265-278
• /
• 2002

A concept test was administered to college students and teachers to identify their understanding of chemical equilibrium and equilibrium shift. The subjects were 53 freshmen in the General Chemistry class, 28 juniors in the Physical Chemistry class and 26 seniors from a university and 10 high school teachers in Seoul. Test items include the calculations of partial pressure and concentration of the gas in the mixture, the equilibrium constant cal-culation and the prediction of equilibrium shift when an inert gas is added to the gaseous reaction system, and the equilibrium concentration calculation and the prediction of equilibrium shift when water or common ion is added to the weak acid solution. The test was focused to identify whether the subjects can predict equilibrium shift using the reaction quotient change for the situations in which Le Chatelier principle is difficult to apply. The results showed that the achievements of teachers and juniors were significantly higher than those of freshmen and seniors. Many stu-dents had difficulties in predicting equilibrium shift using the reaction quotient while they could calculate partial pres-sure and concentration for the same situation. It means they are lack of conceptual understanding of chemical equilibrium shift.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1993.10a
• /
• pp.139-144
• /
• 1993

본 연구에서는 액체를 이용한 위험속도 이상에서 불평형의 반대측으로 액체 를 이동시켜, 이것을 평형질량으로서 이용하여 축의 휘돌림 진폭을 감소시키 는 방안으로서 자기보상형 액체평형장치를 제안하고 기지의 정불평형에 대 한 이론과 실험을 통하여 그 유용성을 검증하고 결과를 나타낸다.

• Journal of the Korean Chemical Society
• /
• v.51 no.4
• /
• pp.365-374
• /
• 2007

The purpose of this study is to investigate the students' conceptions about the reaction rate changes during the chemical equilibrium shifts and also whether the questions about basic concepts of the reaction rate are helpful for the students' understanding of reaction rate changes during the chemical equilibrium shifts. The subjects were 100 students in the 12th grade. The questionnaires were composed of A, B, and A' set, which had to be answered sequentially. The A set consisted of questions asking the change of reaction rate when chemical equilibrium was shifted, the B set was to testify the basic concepts of the reaction rate, and the A' set was the same as the A set. The results showed that the students' understanding of the reverse reaction rate change was lower than that of the forward reaction rate change during the equilibrium shift. Also it was found that students' understanding of the reaction rate change caused by adding the reactant was fairly good while their understanding of the reaction rate change caused by temperature increment was very poor. Since the students marked very high scores in the B set questions, their poor understanding for the reaction rate changes during the equilibrium shifts was not seemed to be due to the lacks of the basic knowledge of reaction rate. Instead, it was due to the failure of applying the basic knowledge of reaction rate to the changes of reaction conditions. It was also found that the average scores of A' set were statistically higher than those of A set. It means the B set items were helpful for the students to solve the A' set items. These results evidenced the possibility of set questionnaires could help the students to connect the related concepts in solving the problems.

• Proceedings of the Korea Society for Simulation Conference
• /
• 2003.06a
• /
• pp.85-88
• /
• 2003

본 논문에서는 다중 프로세서 시스템에서 부하를 재분배할 때 소요되는 통신비용을 줄이기 위한 알고리즘을 제안한다. 또한 시뮬레이션을 이용하여 제안된 알고리즘의 성능을 기존의 알고리즘과 비교한다. 제안하는 알고리즘에서는 되도록 많은 수의 링크가 부하 평형에 참여 할 수 있도록 한다. 이를 위하여 부하 이동량 계산시에 각 프로세서는 자신과 연결된 모든 링크를 이용하여 부하 평형을 시도한다. 그리고 한 번의 링크를 통해 이동되는 부하 량을 단위 량으로 제한시키는 대신에 반복적인 방법으로 부하 이동량을 계산한다. 시뮬레이션은 8$\times$8, 10$\times$10, 12$\times$12, 14$\times$14, 16$\times$16개의 프로세서를 갖는 메쉬 구조에서 실시하였다. 시뮬레이션 결과 기존의 알고리즘에 비하여 전체 부하 이동량은 약 30%, 부하 이동 시간은 약 70% 감소함을 보였다.

• The KIPS Transactions:PartA
• /
• v.11A no.7 s.91
• /
• pp.499-510
• /
• 2004

This paper proposes a heuristic load balancing algorithm for multiprocessor systems. The algorithm minimizes the number of idle links to distribute load traffic and reduces its communication cost. Each processor iteratively tries to transfer unit load to/from every neighbor processors. However, real load transfer is collectively done after complete load traffic calculation to minimize useless traffic. The proposed algorithm can be employed in various interconnection topologies with slight modifications. In this paper, it is applied to both hypercube and mesh environments. For performance evaluation, simulation studies are performed. The performance of proposed algorithm is compared to those of two well-known algorithms. The results show that the proposed algorithm always balances the loads perfectly. Furthermore, it reduces the communication costs by $70{\%}{\~}90{\%}$ in the hypercube ; and it reduces the cost by $\75{\%}$ in the mesh, compared to existing algorithms.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2000.04a
• /
• pp.453-456
• /
• 2000

고정금리 상품의 투자에서 이자율 변동 위험을 피할 수 있는 방법으로 많이 쓰이는 것은 듀레이션을 이용한 면역 모델(Bond Portfolio Immunization Model)로, 이것은 이자율 변동에 대해 포트폴리오의 가격 민감도인 듀레이션을 이용하여 자산과 부채의 변화를 일치시키는 방법이다. 그러나 이 전략은 수익률 곡선이 평형하게 이동한다는 가정(Parallel Shift Term-Structure)을 단점으로 가지고 있어 현실에 적용될 경우 오차가 발생하게 된다. 본 연구에서는 선험적(empirical) 방법으로 평형하지 않은 움직임을 가진 기간구조의 함수(Term-Structure Function)를 정의하고 면역 모델을 부채의 현금흐름에 대해 개별적으로 적용하는 새로운 면역 전략 모델을 구성하고 실험한다

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2015.07a
• /
• pp.90-92
• /
• 2015

국제해사기구는 선박평형수를 통한 수중생물의 이동을 막기 위해, 2004년 선박평형수와 침전물 통제 및 관리를 위한 국제협약을 채택하였으며 2015년 5월12일 현재 73개의 처리장치가 최종승인을 받았거나 진행중이다. 선박평형수 처리기술은 전기분해, 오존식, 자외선식 등 여러 기술이 개발되었으나 비용 및 효율면에서 전기분해방식이 타 방식에 비하여 좋고 간접식과 직접식으로 나누어지며 직접식이 간접식에 비해 우수하다. 본 논문에서는 직접식 전기분해 장치를 이용한 선박평형수 처리시스템 개발에 관해 연구하였다.

• Applied Chemistry for Engineering
• /
• v.10 no.5
• /
• pp.672-676
• /
• 1999

Adsorption isotherm is the most fundamental information in adsorption separation-process. Directly from the elution profile of a peak, the elution-curve method and frontal analysis(FA) were utilized to measure the adsorption isotherm in this work. Using RP-HPLC, sample and the buffer added in mobile phase were 5'-GMP and sodium phosphate, respectively. In this experimental condition, the retention time was decreased with increase in the injected mass of sample. And the front part of a peak was very stiff, so Langmuir adsorption isotherm might be applied. By the elution-curve method, the parameters used in the isotherm were obtained by optimization method, while by the FA, the concentrations of stationary phase were measured from the elution curve and the isotherm was determined by regression analysis. Compared to FA, the consumption of sample was less, and only one or two injections were needed by the elution-curve method. Finally, the effect of concentration of sodium phosphate in mobile phase on the parameters of the isotherm was investigated.

• Applied Chemistry for Engineering
• /
• v.8 no.3
• /
• pp.403-409
• /
• 1997

The equilibrium constants of five deoxyribonucleosides (dDyd, dUrd, dGuo, dThd, dAdo) were estimated by the plate theory and the moment method under isocratic conditions of the Reversed-Phase High Performance Liquid Chromatography (RP-HPLC). The mobile phase in this system was composed of water and organic modifiers(acetonitrile and methanol) The plate theory of linear adsorption isotherm was treated on the basis of continuous flow of eluent through the plates of the column. The moment method was utilized to find the equilibrium constant from the first absolute moment of experimental data. The equilibrium constants of five deoxyribonucleosides in the two methods were very close, and also the equilibrium constants calculated by capacity factor were similar to those by both the plate theory and the moment method. The equilibrium constant was expressed as a semi-log function of the quantity of organic modifier. Excellent agreements between the calculated elusion profile by the plate theory and the experimental data were observed.

• Proceedings of the Korea Air Pollution Research Association Conference
• /
• 2000.11a
• /
• pp.215-216
• /
• 2000

대기 중에 존재하는 입자의 생성 및 변화를 모델링 하는데 있어서 가장 중요한 요소는 응축/휘발 (condensation/evaporation)과 같은 기체/입자간의 상호 과정을 어떻게 모사 하느냐 하는 것이다. 일반적으로 지금까지의 연구는 입자와 가스상의 농도가 순간적으로 평형을 이룬다고 가정해 왔으나 실제 대기상의 입자는 비 평형(non-equilibrium)상태의 응축/휘발 과정을 따르는 것으로 알려져 왔다. (중략)