• Proceedings of the Korean Operations and Management Science Society Conference
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• 1992.04b
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• pp.573-580
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• 1992

인공건물의 평면특성에 대한 시각을 통한 인지를 청각으로 대체했을 경우의 인지능력을 측정하였다. 정상적으로 시각(visual)을 이용하겠으나, 시각 장애자의 경우는 청각(auditory) 또는 촉각(tactile) 또는 두가지 모두를 사용하게 된다. Psychophysical approach를 사용하여 모의평면에 대한 인지능력을 JND단위로 측정하였다. 청각적인 신호를 관찰자에게 제공하기 위해 전자장치(electronic ranging device)가 고안되었다. 이 장치는 목표물까지의 거리를 초음파의 이동시간으로 측정하여 음의세기(sound level)로 발생시켜 준다. 관찰자는 이 음의 세기를 듣고 거리를 추정하고 물표의 방향은 이 장비를 쥔 손의 방향, 즉, proprioceptive cue를 이용하게 된다. 세가지 task에 대한 실험은 평면의 slantness, 두 평면이 교차하는 모서리의 크기, 두 평면사이의 공간(aperture size)등에 대한 인지능력의 측정실험이다. 실험결과를 보면, 관찰자는 시각신호 대신에 청각신호를 사용할 수 있는 능력이 있는 것으로 나타났다. 세가지 task별 JND측정치는 slant angle 6도, 모서리의 concavity 10도, angular aperature size 3-5도로 나타났다. 이 결과는 정상인이 시각을 이용한 인지능력과 큰 차이가 없음을 보여주고 있다.

• Journal of the Korean Operations Research and Management Science Society
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• v.14 no.1
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• pp.31-31
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• 1989

The Generalized Assignment Problem(GAP) determines the minimum assignment of n tasks to m workstations such that each task is assigned to exactly one workstation, subject to the capacity of a workstation. In this paper, we presented a new heuristic search algorithm for GAPs. Then we tested it on 4 different benchmark sample sets of random problems generated according to uniform distribution on a microcomputer.

• Asia-Pacific Journal of Business
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• v.15 no.1
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• pp.113-129
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• 2024

Purpose - This study aims to empirically identify the quantitative effects of work from home (WFH) on employee productivity using field data. Design/methodology/approach - Based on large-scale field data from a South Korean company which introduced the WFH arrangement in 2020, we conducted fixed effect and moderating effect analyses using individual-level panel data over sixty-three weeks. Findings - The empirical analysis generated several findings. It was found that overall, WFH has a positive effect on productivity. However, the productivity impact of WFH was found to vary depending on task characteristics. Specifically, WFH led to over 20% increase in productivity for simple and repetitive tasks. On the other hand, no significant productivity impact was observed for professional and knowledge-based tasks. Research implications or Originality - As the first study based on field data from South Korea, this study offers convincing causal evidence of the moderating impact of task characteristics on the relationship between WFH and productivity. Further, the above findings provide managers with practical insights concerning their work arrangement decisions.

• ETRI Journal
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• v.34 no.3
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• pp.330-340
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• 2012

In many applications of wireless sensor actor networks (WSANs) that often run in harsh environments, the reduction of completion times of tasks is highly desired. We present a new time-aware, energy-aware, and starvation-free algorithm called Scate for assigning tasks to actors while satisfying the scalability and distribution requirements of WSANs with semi-automated architecture. The proposed algorithm allows concurrent executions of any mix of small and large tasks and yet prevents probable starvation of tasks. To achieve this, it estimates the completion times of tasks on each available actor and then takes the remaining energies and the current workloads of these actors into account during task assignment to actors. The results of our experiments with a prototyped implementation of Scate show longer network lifetime, shorter makespan of resulting schedules, and more balanced loads on actors compared to when one of the three well-known task-scheduling algorithms, namely, the max-min, min-min, and opportunistic load balancing algorithms, is used.

• The Journal of Korean Physical Therapy
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• v.26 no.6
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• pp.386-390
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• 2014

Purpose: We aimed to investigate whether visuomotor function would be modulated, when healthy subjects performed tracking task after tDCS application over the primary sensorimotor cortex (SM1) in the non-dominant hemisphere. Methods: Thirty four right-handed healthy participants were enrolled, who randomly and evenly divided into two groups, real tDCS group and sham control group. Direct current with intensity of 1 mA was delivered over SM1 for 15 minutes. After tDCS, tracking task was measured, and their performance was calculated by an accuracy index (AI). Results: No significant difference in AI at the baseline between the two groups was observed. The AI of the real tDCS group was significantly increased after electrical stimulation, compared to the sham control group. Two way ANOVA with repeated measurement showed a significant finding in a large main effects of time and group-by-repeated test interaction. Conclusion: This study indicated that application of the anodal tDCS over the SM1 could facilitate higher visuomotor coordination, compared to sham tDCS group. These findings suggest possibility that tDCS can be used as adjuvant brain modulator for improvement of motor accuracy in healthy individuals as well as patients with brain injury.

• Physical Therapy Korea
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• v.23 no.2
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• pp.1-10
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• 2016

Background: Many studies regarding task-oriented training have recently demonstrated functional improvement in patients with post-stroke hemiparesis. The task-oriented approach is very diverse, and chronic stroke patients must have access to a sustained systematic treatment program to enhance their walking ability. Objectives: This study aimed to compare the effects of the task-oriented circuit training and treadmill training on walking function and quality of life in patients with chronic stroke. Methods: Fourteen patients with chronic stroke volunteered for this study. The subjects were randomly divided into a task-oriented circuit training group and a treadmill training group with 7 patients in each. Each training regimen was performed for 30 min a day and 3 days a week for 4 weeks. Assessment tools included the Timed Up-and-Go Test (TUGT), 10-m Walk Test, 6-min Walk Test (6MWT), and the Stroke Impact Scale (SIS). Results: The change in results of the TUGT, 6MWT, and SIS measured prior to and following the training regimens appeared to be significantly different between the two groups (p<.05). In addition, after the intervention, significant differences were found for all parameters in the task-oriented circuit training group and for the TUGT, 6MWT, and SIS in the treadmill training group (p<.05). Conclusion: The findings suggest that task-related circuit training and treadmill training may be helpful to improve walking function and quality of life of patients with post-stroke hemiparesis. Additionally, a task-related circuit training program may achieve more favorable outcomes than a treadmill program.

• Physical Therapy Korea
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• v.21 no.4
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• pp.34-39
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• 2014

The purpose of this study was to examine the effect of three cognitive tasks on gait at a preferred walking speed, and at a fast speed, using dual-task methodology. A total of 29 stroke patients participated in the study. All 29 subjects performed 2 motor tasks (10-meter walk task and timed up and go task each at a preferred and a fast speed) and three cognitive tasks [Stroop, word list generation (WLG), serial subtraction (SS)] under dual-task conditions [cognitive-motor interference (CMI)] in a randomized order. Gait speeds were measured in six different conditions. A repeated-measure analysis of variance was employed to compare the results of the Stroop training, WLG, and SS tasks during preferred and fast walking. A Bonferroni adjustment use for post hoc analysis. The level of statistical significance was set at ${\alpha}=.05$. A CMI effect occurred for performance of a 10-meter walking task at two different speed and a cognitive task (p<.05). Stroop had a significantly greater effect than SS and WLG (p<.05). The timed up and go task was affected when performed with fast walking speed during Stroop cognitive task (p<.05), but was not affected if performed with preferred walking speed during a cognitive task (p>.05). This study showed that CMI of Stroop can be used as a rehabilitation program for stroke patients.

• Journal of the Korean Operations Research and Management Science Society
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• v.33 no.3
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• pp.1-16
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• 2008

This paper considers a scheduling problem to minimize the total tardiness in the two-stage assembly-type flowshop. The system is composed of multiple fabrication machines in the first stage and a final-assembly machine in the second stage. Each job consists of multiple tasks, each task is performed on the fabrication machine specified in advance. After all the tasks of a job are finished, the assembly task can be started on the final-assembly machine. The completion time of a job is the time that the assembly task for the job is completed. The objective of this paper is to find the optimal schedule minimizing the total tardiness of a group of jobs. In the problem analysis, we first derive three solution properties to determine the sequence between two consecutive jobs. Moreover, two lower objective bounds are derived and tested along with the derived properties within a branch-and-bound scheme. Two efficient heuristic algorithms are also developed. The overall performances of the proposed properties, branch-and-bound and heuristic algorithms are evaluated through numerical experiments.

• Journal of Korean Academy of Nursing
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• v.38 no.6
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• pp.853-865
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• 2008

Purpose: The aim of this study was to develop and to analyze the task of gerontological nurse practitioners (GNPs) in Korea. Methods: The definition of GNP and job description was developed based on developing a curriculum (DACUM) by 7 panels who have experienced in DACUM analysis and gerontological nursing. One hundred sixty nurses who were working at long term care facilities were participated. The questionnaire included frequency, importance, and difficulty of duties, tasks, and task elements. The data were collected in November 2006, analyzed by descriptive statistics. Results: The job description of GNPs in Korea revealed 5 duties, 23 tasks, and 86 task elements. On the all five duties, the highest duty in frequency and in importance was professional nursing care ($3.25{\pm}0.35$, $3.49{\pm}0.29$). But the highest duty in difficulty was research ($3.24{\pm}0.46$). 'Prevent health problem ($3.42{\pm}0.43$, $3.56{\pm}0.33$)', 'Teach other staffs ($2.83{\pm}0.77$, $3.39{\pm}0.43$)', 'Develop the evidence-based standards ($2.43{\pm}0.76$, $3.22{\pm}0.43$)', 'Develop the self ($2.81{\pm}0.65$, $3.26{\pm}0.42$)', and 'Participate the team activities' were the highest score in frequency and in criticality of tasks. 'Provide emotional support to older adults and families ($3.16{\pm}0.41$)', 'Counsel older adults and their families ($3.14{\pm}0.49$)', 'Do clinical research ($3.32{\pm}0.49$)', 'Quality insurance ($3.25{\pm}0.49$)', and 'Build collaborative system ($3.18{\pm}0.47$)' were perceived the most difficult tasks. Conclusion: The political efforts for the legislation of role and task of GNPs were needed.

• Wind and Structures
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• v.14 no.6
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• pp.517-536
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• 2011

The assessment of wind-induced motion plays an important role in the development and design of the majority of today's structures that push the limits of engineering knowledge. A vital part of the design is the prediction of wind-induced tall building motion and the assessment of its effects on occupant comfort. Little of the research that has led to the development of the various international standards for occupant comfort criteria have considered the effects of the low-frequency motion on task performance and interference with building occupants' daily activities. It has only recently become more widely recognized that it is no longer reasonable to assume that the level of motion that a tall building undergoes in a windstorm will fall below an occupants' level of perception and little is known about how this motion perception could also impact on task performance. Experimental research was conducted to evaluate the performance of individuals engaged in a manual tracking task while subjected to low level vibration in the frequency range of 0.125 Hz-0.50 Hz. The investigations were carried out under narrow-band random vibration with accelerations ranging from 2 milli-g to 30 milli-g (where 1 milli-g = 0.0098 $m/s^2$) and included a control condition. The frequencies and accelerations simulated are representative of the level of motion expected to occur in a tall building (heights in the range of 100 m -350 m) once every few months to once every few years. Performance of the test subjects with and without vibration was determined for 15 separate test conditions and evaluated in terms of time taken to complete a task and accuracy per trial. Overall, the performance under the vibration conditions did not vary significantly from that of the control condition, nor was there a statistically significant degradation or improvement trend in performance ability as a function of increasing frequency or acceleration.