• Journal of Korea Society of Industrial Information Systems
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• v.21 no.3
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• pp.13-19
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• 2016

Spark, an in-memory big-data processing framework is popular to use for real-time processing workload. Spark can store all intermediate data in the cluster memory so that Spark can minimize I/O access. However, when the resident memory of workload is larger that the physical memory amount of the cluster, the total performance can drop dramatically. In this paper, we analyse the factors of bottleneck on PageRank Application that needs many memory through experiment, and cluster the Spark with Tachyon File System for using memory to solve the factor of bottleneck and then we improve the performance about 18%.

• Korean Journal of Computational Design and Engineering
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• v.19 no.3
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• pp.272-280
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• 2014

Most of the car navigation systems pzrovide 2D or 3D virtual map-based driving guidance. One of the important issues is how to reduce cognitive burden to the driver who should interpret the abstracted information to real world driving information. Recently, an augmented reality (AR)-based navigation is considered as a new way to reduce cognitive workload by superimposing guidance information into the real world scene captured by the camera. In particular, head-up display (HUD) is popular to implement AR navigation. However, HUD is too expensive to be set up in most cars so that the HUD-based AR navigation is currently unrealistic for navigational assistance. Meanwhile, smartphones with advanced computing capability and various sensors are popularized and also provide navigational assistance. This paper presents a research on cognitive effect and responsiveness of an AR navigation by a comparative study with a conventional virtual map-based navigation on the same smartphone. This paper experimented both quantitative and qualitative studies to compare cognitive workload and responsiveness, respectively. The number of eye gazing at the navigation system is used to measure the cognitive effect. In addition, questionnaires are used for qualitative analysis of the responsiveness.

• Journal of the Korea Society for Simulation
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• v.12 no.3
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• pp.69-81
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• 2003

To manage a cluster of distributed server systems, a number of management aspects should be considered in terms of configuration management, fault management, performance management, and user management. System performance monitoring and reporting take an important role for performance and fault management. In this paper, we present distributed system architecture modeling of a performance monitoring and reporting tool. Modeling architecture of four subsystems are introduced: node agent, data collection, performance management & report, and DB schema. The performance-related information collected from distributed servers are categorized into performance counters, event data for system status changes, service quality, and system configuration data. In order to analyze those performance information, we use a number of ways to evaluate data corelation. By using some results from a real site of a company and from simulation of artificial workload, we show the example of performance collection and analysis. Since our report tool detects system fault or node component failure and analyzes performances through resource usage and service quality, we are able to provide information for server load balancing, in short term view, and the cause of system faults and decision for system scale-out and scale-up, in long term view.

• Physical Therapy Korea
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• v.14 no.3
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• pp.9-15
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• 2007

The purpose of this study was to investigate electromyographic activities of the flexor digitorum superficialis (FDS) and the flexor carpi ulnaris (FCU) by the shape of the ultrasound head. Twelve healthy subjects participated and performed ultrasound therapy with a round head and a long handled head during each 5-minute application. Electromyographic activities of the FDS and FCU were recorded by surface electrodes and normalized by maximal voluntary isometric contraction (MVIC) values. There was no difference in the muscular fatigue of FDS and FCU as determined by the shape of the ultrasound head (p>.05). Without the shape of head, the mean power frequency decreased with the time. There also was no difference in %MVIC of the FDS and FCU as determined by the shape of the ultrasound head (p>.05), but the force exerted exceeded 20%MVIC. There was however a significant difference in the amount of cumulative workload of the FDS and FCU as determined by the shape of ultrasound head (p<.05). The workload was however not affected by the shape of the ultrasound head. Constant static grasp of ultrasound transducer head during ultrasound therapy is considered a high risk factor of work-related musculoskeletal disease.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.6
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• pp.1305-1317
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• 2019

Although encryption for data protection is essential in the big data platform environment of public institutions and corporations, much performance verification studies on encryption algorithms considering actual big data workloads have not been conducted. In this paper, we analyzed the performance change of AES, ARIA, and 3DES for each of six workloads of big data by adding data and nodes in MongoDB environment. This enables us to identify the optimal block-based cryptographic algorithm for each workload in the big data platform environment, and test the performance of MongoDB by testing various workloads in data and node configurations using the NoSQL Database Benchmark (YCSB). We propose an optimized architecture that takes into account.

• Nuclear Engineering and Technology
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• v.54 no.2
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• pp.449-455
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• 2022

The rapid rise in the application of novel treatment techniques, such as intensity-modulated radiotherapy (IMRT), motivated us to survey the status of Korea's radiation safety management and the shielding designs of facilities employing medical linear accelerators (LINACs). To this end, a questionnaire was used to collect information on LINAC facilities and treatments, workload, shielding design, shielding management, and path of obtaining shielding information. Out of 100 domestic institutions, 52 responded to the survey. Approximately 70% of the institutions utilized IMRT for more than 60% of their cases, and an IMRT factor of 5 was adopted by 75% of these institutions. Over 80% of the institutions accounted for the applied time-averaged dose rate per week and instantaneous dose equivalent rates in their shielding designs. Approximately 45% of the institutions obtained important shielding information via a radiation shielding design company and the NCRP-151 report. Overall, most facilities were shown to follow the standards recommended by the relevant international agencies. However, the requirement to establish standardized shielding design information and clarify ambiguous paths for information acquisition was also highlighted. Therefore, the study's results can be used as a foundation for establishing a safety control system and for creating adequate shielding designs.

• Korean journal of aerospace and environmental medicine
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• v.31 no.2
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• pp.38-44
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• 2021

Purpose: This study aimed to identify the prevalence of fatigue and its associated factors leading to the fatigue among Korean commercial airline pilots. Methods: An anonymous, web-based questionnaire collecting data on sleep related characteristics was completed by airline pilots. The final 1,029 samples of completed questionnaires were analyzed. The association of the risk factors with fatigue was determined using logistic regression analysis. Results: The prevalence of fatigue was 60% (Fatigue Severity Scale index≥3.2), disturbed sleep 28% (Pittsburgh Sleep Quality Index≥9), daytime sleepiness 17% (Epworth Sleepiness Scale≥10), and sleep apnea (Berlin Questionnaire≥2) 11%. The fully adjusted logistic regression showed that quality of life (odds ratio [OR]=0.16, confidence interval [CI]=0.11-0.24), daytime sleepiness (OR=1.26, CI=1.18-1.34), sleep quality (OR=1.44, CI=1.29-1.61), mental workload (OR=1.10, CI=1.05-1.14), vigorous physical activity (OR=0.82, CI=0.72-0.92), late starts (OR=1.25, CI=1.06-1.46) and average weekly flying hours (OR=1.02, CI=1.00-1.03) were associated with higher levels of fatigue. Conclusion: Lower quality of life, disturbed sleep, more subjective sleepiness, shorter sleep duration, higher mental workload, less vigorous physical activity, frequent late starts, and longer flying hour were shown to be risk factors for fatigue in airline pilots. These findings should be taken into account in the development of sleep and fatigue countermeasures for airline pilots.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.30 no.4
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• pp.215-221
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• 2022

본 연구는 민간항공 조종사 훈련 및 평가에 중요하게 고려되고 있는 8가지 핵심 역량 향상을 위한 기초자료 마련을 위해 수행되었으며, 그 중 가장 중요하다고 판단되는 상황인식(situation awareness) 및 작업부하 관리에 대해 분석하였다. 예비 조종사를 대상으로 항공기 접근 및 착륙 단계를 진행하는 동안 PM(pilot monitoring) 역할을 수행하며 인식하는 항공기 상황과 작업부하량에 대해 평가하였다. 평가 시나리오는 기본비행훈련장치(basic aviation training device)를 사용하여 지형적 상황인식, 공간/시간적 상황인식, 시스템 상황인식, 환경적 상황인식을 평가할 수 있는 요소로 구성하였으며, 모니터링 도중 의도적인 주의분산 상황을 추가하였다. 연구 결과, 전체 비행 단계에 대한 상황인식은 32.3%이고, 지형적 상황인식(60.3%)이 가장 높고, 시스템 상황인식(18%)이 가장 낮은 것으로 나타났다. NASA-TLX 평가방법으로 측정한 작업부하량은 10.8점(20점 만점)으로 나타났다. 또한, 기초공중항법학을 수강한 예비 조종사들이 대체로 높은 상황인식을 하였고, 작업부하 결과는 지형적 상황인식과 밀접한 상관관계를 가지고 있었다.

• Physical Therapy Korea
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• v.19 no.2
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• pp.69-79
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• 2012

Importance of the work-related musculoskeletal disorders (WMSDs) has been increasing in the hospital industry such as health care industry and financial industry. This study investigated in order to identify the factors like general, occupational and ergonomically characteristics of the subjects related to musculoskeletal disorders (MSDs) of physical therapists (PTs). Ergonomic tools of rapid upper limb assessment (RULA) were used for evaluation workload of the tasks. Prevalence of MSDs were 13 PTs (26.0%) for neck, 31 PTs (62.0%) for shoulder, 9 PTs (18.0%) for arm/elbow, 27 PTs (54.0%) for hand/wrist, 28 PTs (56.0%) for back, 14 PTs (28.0%) for leg/foot. The analysis of the rate of the pain intensity showed that 53.5% subjects experience moderate pain and 14.0% subjects experience severe pain. Factors which were general characteristics, for example, height, ergonomically characteristics such as 'Posture Score A' were related musculoskeletal subjective symptoms in logistic analysis (p<.05). Among physical therapists, action level of RULA were action level 2 (6.0%), action level 3 (52.0%), action level 4 (42.0%). Physical therapists were estimated one of the highest risk factor in this study. This study suggested that the need of preventive education and program for PTs (physical therapists). Comprehensive and systematic management plans should be established to include both ergonomic and sociopsychological aspects.

• Journal of the Korea Convergence Society
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• v.13 no.4
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• pp.613-623
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• 2022

Hospital textile is a necessary which the patient used everyday, that required constant management between supply and consumption. This study applied the service blue print technique to analyze how to provide and supply hospital textile from the stock to the patients in a tertiary hospital, Seoul, South Korea. There are actual or potential process problems identified such as nurses' increasing workload, patient dissatisfaction, and infection risk. After applying blueprint analysis, we suggest the modified processes to overcome theses identified problems using automatization to provide textile. Expected outcomes may include decreases in patient's waiting time, nurse's textile workload, and lower infection risk as well as increasing process efficiency via systematic supply-demand management.