• Geomechanics and Engineering
• /
• 제23권1호
• /
• pp.51-59
• /
• 2020

In this paper, the WEKA platform was used to mine and analyze measured data of floor failure depth and a prediction system of floor failure depth was developed with Java. Based on the standardization and discretization of 35-set measured data of floor failure depth in China, the grey correlation degree analysis on five factors affecting the floor failure depth was carried out. The correlation order from big to small is: mining depth, working face length, floor failure resistance, mining thickness, dip angle of coal seams. Naive Bayes model, neural network model and decision tree model were used for learning and training, and the accuracy of the confusion matrix, detailed accuracy and node error rate were analyzed. Finally, artificial neural network was concluded to be the optimal model. Based on Java language, a prediction system of floor failure depth was developed. With the easy operation in the system, the prediction from measured data and error analyses were performed for nine sets of data. The results show that the WEKA prediction formula has the smallest relative error and the best prediction effect. Besides, the applicability of WEKA prediction formula was analyzed. The results show that WEKA prediction has a better applicability under the coal seam mining depth of 110 m~550 m, dip angle of coal seams of 0°~15° and working face length of 30 m~135 m.

• Safety and Health at Work
• /
• 제5권2호
• /
• pp.86-90
• /
• 2014

Background: Urinary 1-hydroxypyrene (1-OHP) was selected as a biomarker of polycyclic aromatic hydrocarbons (PAHs) to explore the accumulation level in the bodies of workers at rubber smoke sheet factories in southern Thailand. Methods: Spot urine samples were taken from four groups of workers from June 2006 to November 2007. The nonexposure or control groups included habitual cigarette smokers and nonsmokers. The other two groups were workers exposed to particle-bound PAHs from rubber wood smoke and they were nonsmokers. All spot urine samples were analyzed for 1-OHP and creatinine levels. Results: The mean${\pm}$standard deviation urinary 1-OHP in the control group of habitual smokers and the nonsmokers was $0.24{\pm}0.16{\mu}mol/mol$ creatinine and not-detected to $0.14{\mu}mol/mol$ creatinine, respectively. In the workers, the 1-OHP levels on workdays had no significant difference from the 1-OHP levels on the days off. The yearly average 1-OHP level was $0.76{\pm}0.41{\mu}mol/mol$ creatinine whereas the average 1-OHP level during 10 consecutive workdays was $1.06{\pm}0.29{\mu}mol/mol$ creatinine (p > 0.05). Conclusion: The urinary 1-OHP levels of workers exposed to PAHs were high. The accumulation of 1-OHP in the body was not clear although the workers had long working hours with few days off during their working experience. Therefore, a regular day off schedule and rotation shift work during high productive RSS should be set for RSS workers.

• 조명전기설비학회논문지
• /
• 제28권4호
• /
• pp.1-8
• /
• 2014

This study compared the recommended levels of illumination for housing. KS Recommended Levels of Illumination (KS A 3011) in Korea, Recommended Levels of Illumination (GB 50034-2004) in China and Recommended Levels of Illumination (JIS Z 9110) in Japan are compared. The results are as below. First, recommended levels of illumination used in Korea China Japan are suggested by different locations and activities. However, classification for application scope is set differently. There are 10 areas for classification used in Korea, 5 areas in China, and 13 areas in China. When medium levels for classification are included as classification level, total of 15 areas are used for classification in China. Second, when considering there are 15 areas of application scope in China for recommended levels of illumination, there are 7 areas that are commonly used in Korea China Japan. 7 areas include stadium, factories, hospitals, office, shopping center, houses and hospitals. Third, working surface is considered as the height for recommended levels of illumination in Korea China Japan. Korea and Japan consider all working positions, standing and sitting position, when deciding the height. However, China only considers the standing position. Fourth, application scope for recommended levels of illumination for housing are classified in 16 areas in Korea, 5 in China and 18 in Japan. Thus, the application scope for recommended levels of illumination in housing in Korea is similar to Japan. However, there are only 5 areas used in China such as living room, bedroom, dining room, kitchen and sanitary room. Fifth, recommended levels of illumination is classified in 3 levels such as Lowest-Moderate-Highest while China and Japan only have standard recommended levels of illumination. Sixth, when observing recommended levels of illumination by type of activities, Japan classified the activities in greatest detail followed by Korea and then China. Seventh, Recommended levels of illumination differs by each country.

• 복식
• /
• 제57권8호
• /
• pp.14-23
• /
• 2007

The purpose of this study was to investigate the present condition of cold protective clothing for mailman, to improve its design in movement, fitness, and other functions, and supply basic data for its performance evaluation. The results are as follows : The 46.60% of those questioned did not satisfy current clod protective clothing fer mailman. Especially, they considered dissatisfactory in properties such as waterproof, comfort, activity, and sweat absorption. The newly developed cold protective clothing is two-piece style composed of jacket and pants. Both jacket and pants are composed of inner and outer clothing individually. In both jacket and pants, their outer clothing's material was waterproof, windproof, and breathable shell fabric on which PTFE film laminated and their inner clothing's material was 100% polyester Polar polis to have better insulation property. The jacket has attachable cap which can be used as rain gear and set-in sleeve with stand collar. It also had big outside patch pockets and side seam pockets to ensure enough storage space. The pants have knee pads to give free movement to knees and slant side pockets. Inner clothing of both jacket and pants can be worn during working inside without out clothing. Insulation of the newly developed cold protective clothing was not better than current one except right hand, left hand and left foo. It is considered that is because thickness of material is the most important factor to influence insulation.

• 대한인간공학회지
• /
• 제32권4호
• /
• pp.321-331
• /
• 2013

Objective: The aim of this study is to review the literatures on the regulation, standard and guideline for the human vibration in Korea and other countries. Background: This review can be used to prevent various diseases caused by the human vibration as a basis for the development of the policy. Results: In Korea, the general employers' duties related to human vibration are set forth the Health Measures(Article 24) in the Occupational Safety and Health Act. And then an employer shall take measures to protect the health of the workers concerned by improving other working conditions relating to working hours for the vibration prevention measures referred to in Article 24 of the Act. The European Union adopted a Directive in 2002 on minimum requirements for the health and safety of workers exposed to vibration. New Regulations on Vibration at Work will be introduced in Great Britain on 2005 to implement the Directive. In the U.S., both ANSI and ACGIH adopted the ISO standard for measurement and suggested exposure action and limit values. In Japan, the Ministry of Labor decided that the vibration syndrome among operators of rock drills and riveters etc. could be included in an occupational disease(1947). In addition, ISO standard was based on proposals and draft documents of many countries such as U.K, Japan and European, etc. Conclusion: In Korea, Occupational Safety and Health Act prevent vibration to health, but do not include exposure limits. It is therefore important to consider the new duties regarding to vibration risks added to the general duties.

• PNF and Movement
• /
• 제17권3호
• /
• pp.451-461
• /
• 2019

Purpose: This study identified the effect of abdominal muscle contraction using changes in waist circumference for healthcare workers with back pain due to inadequate posture during working hours. Methods: In this study, we provided educational training focused on posture alignment and utilized waist circumference change sensors to induce the contraction of abdominal muscles as a method to address low back pain in healthcare workers. All 32 participants received the same training and then were assigned to two groups: wearing the keeping core band (CB) and not wearing the keeping core band (NCB). For the CB group, the waist circumference change sensor was applied for 6 weeks during working hours. Wilcoxon's signed-ranks test and paired t-tests were used to compare the differences between the groups. All statistical significance levels were set to α=0.05. Results: Trunk muscle endurance increased significantly in the CB group. There was no significant difference in stability index to evaluate static postural control, but active hip abduction tests, which evaluate dynamic postural control, showed significant decrease in the CB group. Conclusion: These results suggest that the induction of abdominal contraction using the waist circumference change sensor may improve the trunk muscle endurance and the postural control ability of the hip and pelvis of healthcare workers.

• 태양에너지
• /
• 제11권3호
• /
• pp.62-73
• /
• 1991

본 연구는 주어진 기름노즐의 분무특성을 실험적으로 조사하고 아울러 적정 가동조건을 설정하기 위하여 수행하였다. 실험에 공시한 노즐은 Delalvan과 Hago(압력분무 Simplex 1.25GPH)로서 각종 압력하에서 분무 각 $60^{\circ}$와 $80^{\circ}$에 대하여 조사하고 분무특성을 기술함에 있어서는 사우터 평균입경의 개념을 사용하였다. 포집된 모든 분무입자는 고감도 필름을 사용하여 50배로 확대 촬영하고, 이들을 Nukiyama-Tanazawa의 분포함수를 도입하여 해석하였다. 결론적으로 $80^{\circ}$의 경우가 $60^{\circ}$의 경우보다 분무특성이 양호하며, 적정 가동조건은 분무압 $8kg/cm^2$ 부근에서 정착됨을 알 수 있었다.

• Journal of Electrical Engineering and Technology
• /
• 제13권5호
• /
• pp.1945-1955
• /
• 2018

High frequency signal injection (HFI) is an alternative method for estimating rotor position of interior permanent magnet synchronous motor (IPMSM). The general method of frequency and amplitude selection is based on error tolerance and experiments, and is usually set with only one group of HF parameters, which is not efficient for different working modes. This paper proposes a novel rotor position estimation scheme by HFI with optimized frequency and amplitude, based on the mathematic model of IPMSM. The requirements for standstill and low-speed operational modes are met by applying this novel scheme. Additionally, the effects of the frequency and amplitude of the injected HF signal on the position estimation results under different operating conditions are analyzed. Furthermore, an optimization method for HF parameter selection is proposed to make the estimation process more efficient under different working conditions according to error tolerance. The effectiveness of the propose scheme is verified by the experiments on an IPMSM motor prototype.

• 과학기술학연구
• /
• 제17권2호
• /
• pp.5-40
• /
• 2017

이 논문의 목적은 산업혁명들의 역사적 흐름을 정리하고 이를 통해 2016년 세계경제포럼이 촉발한 4차 산업혁명론의 위상을 점검하는 데 있다. 우선, 이 논문에서는 1차, 2차, 3차 산업혁명의 전개과정을 검토한 후 해당 산업혁명의 특징을 도출하였다. 그 결과 4차 산업혁명에 관한 논자들이 인식하고 있는 산업혁명의 역사에는 핵심 기술과 시작 연도 등에서 상당한 문제점이 있다는 점을 확인할 수 있었다. 또한 4차 산업혁명이 또 하나의 새로운 산업혁명인지에 대해 의문을 제기하면서 산업혁명이 성립될 수 있는 몇 가지 조건을 제안하였다. 결론적으로 최근에 열광적으로 논의되고 있는 4차 산업혁명은 일종의 작업가설에 불과하며, 한국적 상황에 적합한 미래 비전을 정립하는 것이 필요하다고 지적하였다.

• 디지털산업정보학회논문지
• /
• 제17권3호
• /
• pp.105-119
• /
• 2021

The purpose of this study is to examine the organizational politics, resistance change, turnover intention, and organizational commitment of organizational members during mergers and acquisitions. Recently, many companies are interested in mergers and acquisitions for business diversification and market extension. A merger is a legal consolidation of two entities into one, whereas an acquisition occurs when one entity takes ownership of another entity's stock, equity interests, or assets. This research model establishes a structural equation model. This model is set in a causal relationship between manager's organizational politics, peer organizational politics, and change resistance and the change resistance has a causal relationship of turnover and tissue immersion. In particular, this study will test different of organizational politics by position. Research results, the organizational politics of managers and colleagues have shown increasing change resistance. The change resistance has resulted in a reduction of organizational commitment and an increase of turnover intention. Next, the position analysis showed that top management level, middle management level, and working-level officials showed different organizational politics. The working-level officials are influenced by their manager politics and are influenced in organizational commitment and turnover intention by change resistance. The middle manager level is influenced by the organizational politics of bosses and colleagues, and organizational commitment is weakened by change resistance. The CEO level is not affected by organizational politics in the company, but the turnover intention is strengthened and the organizational commitment is weakened by the change resistance. This study has contributed to further updating the theory of organizational politics based on mergers and acquisitions. As a practical implication, we suggest an organizational integration strategy for a new organization.