• 한국정보과학회논문지:시스템및이론
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• 제33권1_2호
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• pp.1-14
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• 2006

대용량 볼륨 데이타를 가시화하는 효과적인 방법인 후-정열 병렬 렌더링은 부하균형에 의해 성능이 결정된다. 기존의 정적 데이타 분할 방법은 태스크 병렬성만의 관점에서는 자기균형을 쉽게 얻을 수 있었지만, 데이타 내부의 빈 공간을 고려하지 않았기 때문에 데이타 병렬성의 관점에서는 심각한 불균형을 초래할 수 있었다. 본 논문은 태스크 병렬성과 데이타 병렬성이 함께 고려된, 적응적이며 확장적인 부하 균형 기법을 제안한다. 우리는 계층적 자료 구조인 옥트리와 BSP-트리를 효과적으로 결합하여 볼륨 데이타의 실제 영역만을 추출하여 렌더링 노드들로 균등하게 분산시켰으며, 각 렌더링 노드들에서는 3차원 클러스터링 알고리즘을 적용하여 렌더링 순서를 효과적으로 결정하였다. 제안하는 방법은 기존의 정적 데이타 분산 기법에 비해 최대 22배의 병렬성을 높였고 동기화 비용을 낮추어 렌더링 성능을 크게 향상시켰음을 실험을 통해 알 수 있었다.

• Structural Engineering and Mechanics
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• 제70권2호
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• pp.169-178
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• 2019

The replacement of damaged components is an important task for long-span bridges. Conventional strategy for component replacement is to close the bridge to traffic, so that the influence of the surrounding environment is reduced to a minimum extent. However, complete traffic interruption would bring substantial economic losses and negative social influence nowadays. This paper investigates traffic control technologies without interruption for component replacement of long-span bridges. A numerical procedure of traffic control technologies is proposed incorporating traffic microsimulation and site-specific data, which is then implemented through a case study of cable replacement of a long-span cable-stayed bridge. Results indicate traffic load effects on the bridge are lower than the design values under current low daily traffic volume, and therefore cable replacement could be conducted without traffic control. However, considering a possible medium or high level of daily traffic volume, traffic load effects of girder bending moment and cable force nearest to the replaced cable become larger than the design level. This indicates a potential risk of failure, and traffic control should be implemented. Parametric studies show that speed control does not decrease but increase the load effects, and flow control using lane closure is not effectual. However, weight control and gap control are very effective to mitigate traffic load effects, and it is recommended to employ a weight control with gross vehicle weight no more than 65 t or/and a gap control with minimum vehicle gap no less than 40 m for the cable replacement of the case bridge.

• 대한산업공학회지
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• 제32권3호
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• pp.236-241
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• 2006

Monitor height is one of the key factors in the VDT workstation design. Most of the previous studies have focused on traditional VDT workplace where the operators performed data entry or word processing tasks using single monitor. This study aimed to suggest proper monitor height when the main task was monitoring information from different number of information sources. Twelve male students participated in three experiments: single information source (one monitor), two information sources (one monitor and one CCTV), and three information sources (one monitor, one CCTV and a window). Subjects performed monitoring tasks for 10 minutes with 3 different monitor center heights : 89.0 cm (Low), 111.3 cm (Middle), and 124.8 cm (High). Surface EMG signals of five neck muscles, subjective discomfort ratings, preference, and working postures were recorded. Results indicated that the middle height was proper for one monitor condition, but the low monitor height was recommended for more than two information sources.

• 영어어문교육
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• 제16권4호
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• pp.239-265
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• 2010

This study investigates the effects of corpus-based vocabulary tasks on the acquisition of English vocabulary in an attempt to explore the influence of corpus use on EFL pedagogy. For this to be realized, a total of 40 Korean high school students participated in the study over a 4-week period. An experimental group used a set of corpus-based tasks for vocabulary learning, whereas a control group carried out a traditional task (i.e., the L1-L2 translation) for vocabulary learning. To assess learning gains, the students were asked to complete the pre- and post-treatment tests measuring the word form, meaning, and use aspects of target lexical items. Results of the study indicate that in the experimental group the corpus-based vocabulary tasks were beneficial for the learning of word forms and use. In particular, corpus-based benefits were greatest in the low-proficiency EFL learners' collocational aspects of vocabulary use. On the other hand, in the control group, the traditional vocabulary tasks benefited the meaning aspects of target vocabulary items the most. In addition, survey results revealed that most students were positive about the corpus-based learning experience although some expressed reservations about the heavy cognitive load and the time-consuming nature of the analysis of corpus data primarily due to learners' lack of language proficiency.

• 아동학회지
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• 제9권2호
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• pp.133-156
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• 1988

This study investigated developmental change with reference to continuity theory in the acquisition of concepts of kin relation, task difficulty with reference to cognitive complexity, and interrelationships in the performance of cognitive tasks of kinship concepts with reference to cognitive parallelism. The subjects consisted of 6-, 8-, 10, and 12-year-old randomly selected children attending kindergartens or elementary schools in Seoul. The schools were located in various residental areas regarded as either middle or lower class. The 81 boys and 80 girls participated in 3 experiments on classification, seriation, and grouping. The instrument for the classification, seriation, and grouping tasks was composed of 10 10cm black on white line drawings of the head and upper torso area of persons in kin relationship. The data was analyzed with MANOVA. A significant age effect was found in the 3 quasi- experiments. There were significant effects on task difficulty. The biosocial power distribution indirectly influenced children's acquisition of kin relational concepts; that is, children performed better in male-kin than in female-kin tasks. There was a high correlation in performance between the 3 cognitive tasks. These findings support the continuity theory (except for seriation), a model which arranges kin-names in order of cognitive load, the centric status of men in society, and the theory of cognitive developmental parallelism.

• 산업안전기술지
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• 제3권1호
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• pp.11-17
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• 2003

In recent years, work-related musculoskeletal disorders (WMSDs) are one of major issues in occupational safety and health in Korea, since the number of injured workers has rapidly increased and the related regulation was amended to improve the work conditions. Main risk factors of WMSDs in Korean industries include manual handling of heavy weight loads, awkward postures, repetitive tasks, prolonged static muscle contraction, and so on. in this article, some ergonomics case studies for identifying the risk factors of WMSDs and far their prevention were introduced. They include a biomechanical analysis for the heavy-weight handling task in a machine-repair shop, physiological evaluation of backpack-carrying tasks in a beverage delivery job, and a set of psychophysical studies to evaluate static-postural load. These studies showed that there are several different ergonomic approaches to identifying and evaluating risk factors of WMSDs and to eliminating them or reducing their levels, and that it is important to select proper methods and apply them in improving the work conditions according to the characteristics of the task. In addition, it needs to develop practical and effective ergonomic tools to prevent WMSDs and to provide these tools to the safety managers in the field so that they can improve the tasks by themselves.

• 한국통신학회논문지
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• 제28권1B호
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• pp.27-32
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• 2003

본 논문에서는 고속 네트웍 기반의 분산 병렬 시스템에서 다양한 내재 병렬 형태를 갖는 프로그램의 효과적인 수행을 위한 유전자 알고리즘 기반의 태스크 스케쥴링 방법(Genetic Algorithm based Task Scheduling GATS)을 제안한다. 분산병렬 시스템은 고속 네트웍을 통해 연결되어진 다수의 범용, 병렬, 벡터 컴퓨터들로 구성되어진다. 분산병렬 처리의 목적은 다양한 내재 병렬 형태를 갖는 연산 집약적인 문제들을 다수의 고성능 및 병렬 컴퓨터들의 각기 다른 능력을 최대한 이용하여 해결함에 있다 분산병렬 시스템에서 스케쥴링을 통하여 더 많은 속도향상을 얻기 위해서는 시스템간의 부하 균형보다는 태스크와 병렬 컴퓨터간의 병렬특성의 일치가 주의 깊게 다루어져야 하며 태스크의 이동으로 인한 통신 오버헤드가 최소화되어야 한다 본 논문에서는 유전자 알고리즘의 동작이 병렬 특성을 감안하여 이루어질 수 있도록 초기화 방법과 지식 기반의 mutation 방법을 제안한다.

• 한국산업보건학회지
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• 제18권3호
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• pp.239-247
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• 2008

Low back disorders (LBDs) have been the most common musculoskeletal problem in Korean workplaces. It affects many workers, and is associated with high costs to many companies as well as the individual, which can negatively influence even the quality of life of workers. The _evaluation of low back disorder risk associated with manual materials handling tasks can be performed using variety of ergonomic assessment tools such as National Institute for Occupational Safety and Health (NIOSH) Revised Lifting Equation (NLE), the Washington Administrative Code 296-62-0517 (WAC), the Snook Tables etc. But most of these tools provide limited information for choosing the most appropriate assessment method for a particular job and in finding out advantage and disadvantage of the methods, and few have been assessed for their predictive ability. The focus of this study was to _evaluate spinal loads in real time with lifting and pulling heavy cow leathers in variety of postures. Data for estimating mean trunk motions were collected as employees did their work at the job site, using the Lumbar Motion Monitor. Eight employees (2 males, 6 females) were selected in this study, in which the load weight and the vertical start and destination heights of the activity remained constant throughout the task. Variance components (three dimensional spaces) of mean trunk kinematic measures were estimated in a hierarchical design. They were used to compute velocity and acceleration of multiple employees performing the same task and to repetitive movements within a task. Therefore, a results of this study could be used as a quantitative, objective measure to design the workplace so that the risk of occupationally related low back disorder should be minimized.

• 대한산업공학회지
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• 제26권1호
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• pp.54-65
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• 2000

The objective of this study is to evaluate the operator performance relating to hand switches with two or three buttons in the main control rooms of nuclear power plants. Based on the comparative analysis of the nuclear power plants, two different subjective workload-rating scales were used to evaluate the performance of 48 operators: the Overall Workload(OW) and National Aeronautics and Space Administration Task Load Index (NASA TLX). The survey questions consisting of the eight-items were asked to evaluate the operating experiences for the two different switch types. The OW scales ratings were applied to measure the workload of the switch-related tasks. The ratings revealed that signal detection tasks caused less workload in the three-buttoned-switch operators than the other switch group. However, in the switch operation tasks, the switch types did not show statistically significant effects on workload level. The NASA TLX scale ratings were performed based on detailed task scenarios that assumed the accident of small break loss of coolant, what we call, the small LOCH. The NASA TLX was administered to three different task groups: the reactor, the turbine, and the electric operator groups. Based on the NASA TLX, the two-buttoned switch groups showed higher workload than those with the three-buttoned switches. However, a statistically significant difference was found only in the reactor operator groups. When the current switch type was assumed to be changed for the other type, all of the three-buttoned switch groups were predicted to have higher workload than the other switch groups, respectively. The implications of these findings were discussed.

• 한국통신학회논문지
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• 제23권6호
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• pp.1409-1418
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• 1998

최근의 오디오 압축 알고리듬은 다양한 코딩 기법을 조합하여 사용하고 있다. 이들은 DSP 작업(DSP task), 제어 작업(controller task), 그리고 혼합 작업(mixed task)으로 나눌 수 있다. 기존의 DSP 프로세서들은 이들 중 DSP 작업만을 효율적으로 설계되어 있어 제어작업이나 혼합작업에 대해서는 자원을 효율적으로 활용하지 못하는 단점이 있다. 본 논문에서는 기존의 DSP 프로세서가 가지는 DSP 작업에 대하여 고성능을 그대로 유지하면서 제어작업과 혼합작업에서도 좋은 성능을 가지는 새로운 구조를 제안하고 구현하였다. 제안된 프로세서 YSP-3는 4개의 실행 유닛 (곱셈기, 2개의 ALU, 메모리 접근 유닛)을 병렬로 배치한 후 4-way 수퍼스칼라명령어 구조를 사용하여 각 우ㅠ닛을 독립적으로 사용할 수 있도록 하였다. 제안된 구조는 일반적인 DSP 알고리듬과 AC-3 디코딩 알고리듬을 실행하여 성능을 평가하였다. 마지막으로 VHDL을 통해 $0.6\$\mu$textrm{m}$-3ML 표준셀 기술로 합성한 후 Compass상에서 모의실험으로 통해 33MHz의 시스템 클럭에 대해 최대 지연시간 상황에서 실시간 동작을 확인하였다.