• PNF and Movement
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• v.16 no.1
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• pp.115-123
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• 2018

Purpose: The aim of this study was to investigate the effect of mandible position on proprioception and range of motion (ROM) during neck stabilization exercise using a sling in healthy adults. Methods: The subjects were randomly assigned to either a sling exercise and mandible open group (n=10) or a sling exercise and mandible closed group (n=12). The sling exercise-mandible open group and sling exercise-mandible closed group took part in an exercise program for 30min, three times per week for 4 weeks. After each training session, head repositioning accuracy (HRA) and the ROM of the cervical spine were measured. Wilcoxon's test was conducted to verify changes within each group, and the Mann-Whitney U test was performed to examine between-group differences. Results: The HRA of the cervical spine was significantly increased during left rotation and extension in the sling exercise-mandible open group. In addition, there were significant differences in both rotations and extension in the two groups. The ROM of the cervical spine increased significantly during both rotations in the sling exercise-mandible closed group. In addition, there was a significant difference in right rotation and extension in both groups. Conclusion: Cervical stabilization exercise using a sling, with the mandible closed increased proprioception and the ROM of the cervical spine.

• Proceedings of the ESK Conference
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• 1996.04a
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• pp.113-127
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• 1996

In Human Reliability Analysis(HRA), the uncertainties involved in many factors that affect human reliability have to be represented as the quantitative forms. Conventional probability- based human reliability theory is used to evaluate the effect of those uncertainties but it is pointed out that the actual human reliability should be different from that of conventional one. Conventional HRA makes use of error rates, however, it is difficult to collect data enough to estimate these error rates, and the estimates of error rates are dependent only on engineering judgement. In this paper, the error possibility that is proposed by Onisawa is used to represent human reliability, and the error possibility is obtained by use of fuzzy reasoning that plays an important role to clarify the relation between human reliability and human error. Also, assuming these factors are connected to the top event through Fault Tree structure, the influence and correlation of these factors are measured by fuzzy operation. When a fuzzy operation is applied to Fault Tree Analysis, it is possible to simplify the operation applying the logic disjuction and logic conjuction to structure function, and the structure of human reliability can be represented as membership function of the top event. Also, on the basis of the the membership function, the characteristics of human reliability can be evaluated by use of the concept of pattern recognition.

• Nuclear Engineering and Technology
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• v.52 no.1
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• pp.87-100
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• 2020

Performance shaping factors (PSFs) in a human reliability analysis (HRA) are one that may influence human performance in a task. Most currently applicable HRA methods for nuclear power plants (NPPs) use PSFs to highlight human error contributors and to adjust basic human error probabilities (HEPs) that assume nominal conditions of NPPs. Thus far, the effects of PSFs have been treated independently. However, many studies in the fields of psychology and human factors revealed that there may be relationships between PSFs. Therefore, the inter-relationships between PSFs need to be studied to better reflect their effects on operator errors. This study investigates these inter-relationships using two data sources and also suggests a context-based approach to treat the inter-relationships between PSFs. Correlation and factor analyses are performed to investigate the relationship between PSFs. The data sources are event reports of unexpected reactor trips in Korea and an experiment conducted in a simulator featuring a digital control room. Thereafter, context-based approaches based on the result of factor analysis are suggested and the feasibility of the grouped PSFs being treated as a new factor to estimate HEPs is examined using the experimental data.

• Journal of Korean Society of Forest Science
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• v.96 no.3
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• pp.259-268
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• 2007

This study was conducted to produce forest thematic maps and estimate forest statistics for Pyeongchang Gun using the kNN technique, which has been applied to produce thematic maps of variables of interest including unobserved plots by combining field plot data, remotely sensed data and other digital map data in forest inventories. The estimation errors for three horizontal reference areas (HRAs), whose radii are 20, 40 and 60 km respectively, were compared. Although the precision for the 40 km radius was lower compared to that for the 60 km radius, the 40 km radius was found to be an efficient HRA because their difference in precision was modest. At a value of k=5 nearest neighbors for the selected HRA, the overall accuracy was high. As a result, using the k=5 neighbors within the HRA of 40 km radius, thematic maps of number of trees, basal area, and growing stock per hectare were generated. As compared to the forest statistics based on field sample plots, the estimated means of each parameter from the produced maps were underestimated.

• Journal of Korean Society of Forest Science
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• v.101 no.3
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• pp.374-380
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• 2012

The k-Nearest Neighbor (kNN) technique is popularly applied to assess forest resources at the county level and to provide its spatial information by combining large area forest inventory data and remote sensing data. In this study, two approaches such as distance-weighting and stratification of training dataset, were compared to improve kNN-based forest growing stock estimates. When compared with five distance weights (0 to 2 by 0.5), the accuracy of kNN-based estimates was very similar ranged ${\pm}0.6m^3/ha$ in mean deviation. The training dataset were stratified by horizontal reference area (HRA) and forest cover type, which were applied by separately and combined. Even though the accuracy of estimates by combining forest cover type and HRA- 100 km was slightly improved, that by forest cover type was more efficient with sufficient number of training data. The mean of forest growing stock based kNN with HRA-100 and stratification by forest cover type when k=7 were somewhat underestimated ($5m^3/ha$) compared to statistical yearbook of forestry at 2011.

• Proceedings of the ESK Conference
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• 1996.10a
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• pp.111-118
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• 1996

THERP(Technique for Human Error Rate Prediction) 방법론은 원전의 확률론적 위험성 평가(PSA)시 운전원과 작업자의 정량적인 인간오류평가에 가장 널리 사용되고 있는 방법이다. HRA Handbook이라고도 불리는 이 모델은 운전원 행위를 시스템 부품의 한 요소로 가정하고 인간오류를 평가한다. 본 논문은 이 방법론을 이용하여 원전 등과 같이 위험시설물 중의 하나인 개스밸브 기지에서의 작업자 보수시 인적오류를 평가하고 기계적 오류와 함께 인적오류 의 기여도를 계산하였다. 본 눈문에서는 이 방법론이 원전, 개스밸브 기지 뿐만아니라 석유화 학 플랜트와 같은 위험시설물의 인적오류 평가에도 유연하게 사용될 수 있음을 보여주었다.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.11a
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• pp.381-388
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• 1996

THERP (Technique for Human Error Rate Prediction) 방법론은 원전의 확률론적 위험성 평가 (PSA)시 운전원과 작업자의 인간오류평가에 가장 널리 사용되고 있는 방법이다. HRA Handbook 이라고도 불리는 이 모델은 운전원 행위를 시스템 부품의 한 요소로 가정하고 인간오류를 평가한다. 본 논문은 이 방법론을 이용하여 원전 등과 같이 위험시설물 중의 하나인 개스밸브기지에서의 작업자 보수시 인적오류를 평가하고 기계적 오류와 함께 인적오류의 기여도를 계산하였다. 본 방법론은 원전, 개스밸브 기지 뿐만아니라 석유화학 플랜트와 같은 위험시설물의 인적오류평가에도 유연하게 사용될 수 있음을 보여주었다.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2002.05a
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• pp.346-355
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• 2002

THERP (Technique for Human .Error Rate Prediction) 방법론은 원전의 확률론적 위험성 평가(PSA)시 운전원과 작업자의 인간오류평가에 가장 널리 사용되고 있는 방법이다. HRA Handbook이라고도 불리는 이 모델은 운전원 행위를 시스템 부품의 한 요소로 가정하고 인간오류를 평가한다. 본 논문은 이 방법론을 이용하여 원전 등과 같이 위험시설물 중의 하나인 개스밸브기지에서의 작업자 보수시 인적오류를 평가하고 기계적 오류와 합께 인적오류의 기여도를 계산하였다 본 방법론은 원전, 개스밸브기지 뿐만아니라 석유화학 플랜트와 같은 위험시설물의 인적오류 평가에도 유연하게 사용될 수 있음을 보여주었다.(중략)

• Nuclear Engineering and Technology
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• v.52 no.6
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• pp.1180-1187
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• 2020

A team of operators is required for nuclear power plant operation, and communication between the operators is an important aspect of the team's ability to successfully carry out tasks. It has been difficult to evaluate the quality of this communication though, and as the relationship between communication quality and team performance has yet to be clarified, it has not been applied to most human reliability analysis (HRA) methodologies. This study investigates the relationship between the quality of communication and team performance using data from a full-scope training simulator of a digital main control room (MCR). Two important characteristics of communication were considered to determine quality: each operator's ability to self-confirm the status of a given task in a digital MCR, and the type of communication, as divided into 1-way, 2-way, and 3-way between operators. To measure team performance, the concept of an unsafe act was employed, which is defined as a human error that has the potential to negatively affect plant safety. Analysis results showed that the communication quality and team performance were related to each other. With this more clearly defined relationship, the results of this study can be applied to related performance shaping factors to improve HRA.

• Journal of Environmental Health Sciences
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• v.40 no.5
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• pp.397-406
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• 2014

Objectives: Perchloroethylene (PCE) is a volatile chemical widely used as a solvent in the dry-cleaning and textile processing industries. It was evaluated as Group 2 "probably carcinogenic to humans" by the Integrated Risk Information System (IRIS) of the United State Environmental Protection Agency (U.S. EPA) in 2012. In order to provide a scientific basis for establishing risk management measures for chemicals on the national priority substances list, aggregate risk assessment was conducted for PCE, included in the top-10 substances. Methods: We conducted the investigation and monitoring of PCE exposure (e.g., exposure scenario, detection levels, and exposure factors, etc.) and assessed its multi-media (e.g., outdoor air, indoor air, and ground water) exposure risk with a deterministic and probabilistic approach. Results: In human risk assessment (HRA), the level of human exposure was higher in the younger age group. The exposure level through inhalation at home was the highest among the exposure routes. Outdoor air or uptake of drinking water represented less than 1% of total contributions to PCE exposure. These findings suggested that the level of risk was negligible since the Hazard Index (HI) induced by HRA was below one among all age groups, with a maximum HI value of 0.17 when reasonable maximum exposure was applied. Conclusion: In conclusion, it was suggested that despite low exposure risk, further studies are needed considering main sources, including occupational exposure.