• 대한기계학회논문집A
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• 제27권6호
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• pp.1007-1013
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• 2003

As environmental restriction kas continuously become more strict, machining technology has emphasized on development of environment-friendly technology. In cutting technology, it has been well recognized that cutting fluids might have undesirable effects on workers health and working environment. In this study, compressed cold air was used as a replacement for conventional cutting fluids. The cooling effect on cutting tool was analyzed using the finite element method and the computational fluid dynamics. This study focused on the temperature simulation of cutting tool by real flow analysis of cold air. The maximum flow rate and the minimum temperature of compressed cold air are 300ι/min and -30$^{\circ}C$ respectively. To compare the simulation and experimental results, inner temperature of the cutting tool was measured with the thermocouple embedded in the insert. The results show that the analysis of cutting temperature using FEM and CFD is resonable, and the replacement of cutting fluid with cold air is available.

• 한국농공학회논문집
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• 제59권4호
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• pp.75-83
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• 2017

Many parts of problems in livestock industry today are associated with organic dust. Endotoxin and toxic gasses on the surface of dust and dust itself can cause aesthetic displeasure and respiratory disease. It also reduces livestock productivity by suppressing immunity of animals and carrying microbes causing animal disease. However, dust level of cattle farm was rarely reported in Korea, and regulation for cattle farm worker does not exist. In this paper, dust concentration and environmental condition were regularly monitored in a commercial Korean native cattle farm. The measurement was conducted according to location and working activities. From the measurement, distribution of dust concentration was affected by wind environment, as the result of natural ventilation. TMR mixer was a major source of dust in target cattle house. The maximum inhalable dust concentration was 637.8 times higher than exposure limit as feed dropped into the TMR mixer. It was expected that dust generation could be affected by particle size and drop height of feed. This study suggests potential risk of dust in cattle farm, and necessity for latter study. Effect of aerodynamic condition and TMR processing should be investigated for dust reduction study.

• 한국산업보건학회지
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• 제23권4호
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• pp.348-355
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• 2013

Objectives: In working environment measurement, sampling is an important stage for obtaining reliable result as analysis. A personal air sampling pump is one of the most fundamental and important element in the work environment measurement, but it remains at the level of calibrating the flow rate of the pump before and after sampling. There is no checking whether the flow rate set at the initial stage would be hold during sampling. The purpose of this study was to develop a method to evaluate the flow rate performance of particulate sampling pump with three-pieces cassette holder containing filters commonly used to sample particulate. Materials and methods: We tested back pressure of particulate sampling pumps commonly used in Korea with three-pieces cassette holder containing various filters, and tried to find out the combination conditions of filters in accordance with back pressure required by ISO standard 13137. Results: We found out the matrix of sampling media such as three-pieces cassette holder containing filters applicable to the pressure drop required by the ISO standard for evaluating the flow rate stability under increasing pressure drop and long term(8 hour) performance. Conclusions: This evaluation method using sampling media matrix for checking flow rate stability proposed by this study could be very useful tool to find out good performance pumps before sampling.

• 한국직업건강간호학회지
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• 제10권2호
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• pp.174-182
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• 2001

This study was performed to find out the differences between noise levels of hospital wards and the nurses efforts for noise management in some general hospitals. The hospital wards selected were the intensive care unit(ICU), the emergency room(ER), the nursery room(NR), the internal medicine(IM), the general surgery(GS) among the 5 general hospitals located in Seoul. The data were collected from August 3 to September 13, 1999 through questionnaire survey and noise measurement in each nursing station of hospital wards. Data analysis was done by SPSS 8.0 package among the 305 questionnaires and 24 hours monitored noise levels. Frequency, Chi-square and ANOVA test were used. The study results were as belows: 1. The noise level measured by 24 hours monitoring survey were exceeded on the standard limit in all the hospital wards. Data also showed that noise levels were significantly different in each ward among the three shifts working duties. 2. The subjects were all female nurses. They were mostly working in the ICU ward(28.9%). They were 26~30 years old (43.9%), junior college graduates(57.0%), working for 1~5 years(55.1%) as staff-nurse(85.6%). There were no significant differences between hospital wards and general characteristics of nurses. 3. The noise levels perceived by nurses were regarded as 'Highly noisy'(56.4%), especially during the 11:30 and 15:30 (30.2%) o'clock. Data also showed that noise education was not ever given to nurses(89.9%). Nurses also responded that they hardly put an effort to reduce noise level(54.8%). However, there were significant differences between wards and noisy working time, experience of noise education and level of effort for noise reduction. 4. Nurses also perceived the ventilator alarm and EKG-alarm as the most disturbing sounds in the ICU, human voice and telephone ringing in the ER, human voice and EKG-alarming in the NR, human voices and telephone ringing in IM and GS both wards respectively in order. There were significant differences between hospital wards and noise making factors. 5. Nurses were shown that they regarded highly 'Sound reduction of the human voice', 'Careful handling on medical instruments', and 'Immediate appliances on alarming materials' as the practical method for noise management. There were significant differences between hospital wards and behavioral practical efforts for noise management. According to that results, the statistical differences were shown in the 24 hour monitored noise levels in each ward. Also, nurses perceived the noise severity differently and they approached variously on the practical efforts for noise reduction in each ward. Thus, author thinks that concrete and systematic endeavor will be necessary for noise reduction and management in hospitals for better working and healing environment for both of patients and staffs.

• 대한치과기공학회지
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• 제33권1호
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• pp.93-102
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• 2011

Purpose: The study aimed to evaluate working environment for dental technician by measuring dust level, ventilation conditions and the use of personal protective equipment and to provide basic information required to improve working environment and develop health education programs for dental technician. Methods: A total of 240 dental technician who are registered with the Daegu Association of Dental technician and working at 34 dental laboratories participated in the study. And the dust level was measured at 21 different spots in 16 dental laboratories out of 34. Results: Of 34 dental laboratories, 31 (91.2%) were equipped with a ventilator, but the remaining 3 (8.8%) did not have a ventilator. By the number of ventilator, 1 to 3 ventilators were found in 22 dental laboratories (71.0%), 4 to 6 ventilators were in 7 laboratories (22.5%) and more than 7 ventilators in 2 laboratories(6.5%). According to the frequence of changing filters in dust collector, 20 dental laboratories (58.9%) changed filters every four weeks, 10 laboratories (29.4%) changed them every six weeks and 4 laboratories (11.7%) changed them every eight weeks. Of total respondents, 114 (61.3%) said they wore a mask all the time while working, 56 (29.6%) said they frequently wore a mask, 19 (10.1%) said they did not wear a mask. As for the type of masks, 159 (84.1%) used a disposable mask, 25 (13.2%) used a cotton mask and 5 (2.7%) used an anti-dust mask. For dust sat on their outfits while working, 102 (54.0%) shook their uniforms inside workplace to keep dust off the uniforms, 64 (33.9%) did not anything until they wash their uniforms and 23 (12.1%) shook their uniforms outside workplace to keep dust off the uniforms. Of total respondents, 182 (96.3%) had a particle in their eyes while carrying out grinding work. Based on the measurement of floating dust at workplace, 3 dental laboratories showed dust concentration exceeding the minimum level of 10 mg/$m^3$ allowed under the permit for environment. Of those, 1 laboratory had the dust concentration that was more than 1.5 times higher than the minimum level. Dust concentration was higher in laboratories that used a dust collector with 0.5 horse power and changed filters more than 3 weeks ago. Dust comprised of nickel (more than 70%), chrome (9%) and others. The mean chrome concentration was more than twice higher than the minimum permissible level of 0.5 mg/$m^3$. There were two laboratories that showed chrome concentration exceeding the level of 0.4 mg/$m^3$. Like dust concentration, chrome level was higher in laboratories that used a dust collector with 0.5 horse power and changed filters more than 3 weeks ago. There were six laboratories that had nickel concentration exceeding the minimum permissible level of 1 mg/$m^3$. Of those, one laboratory had nickel concentration that was more than three times higher than the minimum permissible level. Nickel concentration was also higher in laboratories that used a dust collector with 0.5 horse power and changed filters more than 3 weeks ago. Conclusion: It is not likely that heavy metal concentrations found in the study constitute respiratory dust. It is however necessary for health of dental technician to apply the Industrial Safety and Healthy Law to dental laboratories and make recommendations for the use of personal protective equipment, installation of a proper number of ventilators, more frequent change of filters in dust collector and improved ventilation for polishing work. At the same time, dental technician need education on how to use personal protective equipment and how to efficiently remove dust from their uniforms.

• 생물환경조절학회지
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• 제13권1호
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• pp.1-7
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• 2004

본 연구는 오이수확기의 매니퓰레이터 개발을 위한 기구학적 분석을 하는 것이다. 매니퓰레이터의 정방향 기구학 및 역방향 기구학 분석을 한 후 실제 장치의 반복오차 측정실험을 통해 이론 값을 검증하였다. 매니퓰레이터는 총 세 개의 링크로서 한 개의 수직링크와 두 개의 호전링크로 구성되어져 있으며, 세 개의 스테핑 모터가 각 관절에 장착되어 링크에 동력을 전달한다. 주요 연구결과를 요약하면 다음과 같다. D-H Parameter를 이용하여 정방향 기구학에 의한 매리퓰레이터의 변환 연산자를 얻었다. 역방향 기구학의 해는 두가지로 나타났으며 삼각함수를 이용하여 해를 구하였다. 매리퓰레이터의 반복오차를 측정한 검증 실험에서는 X, Y, Z축에 대하여 반복 오차가 최대 2.60mm, 2.05mm, 1.55mm로 나타났으며, 정방향 및 역방향 기구학에서 오차의 최대지점 및 최소지점의 실제 좌표는 일치하였다. 반복오차 측정 결과는 매리퓰레이터의 목표지점인 오이의 직경에 비해 비교적 작게 나타났다. 측정오차는 실험중 발생한 실험오차로 판단된다. 매니퓰레이터의 오차를 줄이고 작업능률의 향상을 위해서는 링크의 수를 줄이고 오이의 품종 및 재배환경을 고려하여야 하며, 경량이면서도 견고한 재료를 사용하여 하중을 줄여야 한다.

• 인터넷정보학회논문지
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• 제11권1호
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• pp.183-193
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• 2010

조직의 성과 향상을 위한 정보시스템 설계, 구성, 실행 노력은 정보기술 활용을 조직 전략과 연계하여 경쟁적 우위를 확보하는 방향으로 이루어져 왔다. 하지만 국내 중소기업의 정보화는 자금, 인력 등의 측면에서 매우 열악한 환경에 머무르고 있다. 중소기업의 열악한 환경을 극복하기 위해 조직 내 정보시스템 수준을 올바르게 평가하고, 정보화 투자가 향후 경쟁력 강화에 기여한다는 이론적 대안을 추구하고 있다. 본 연구에서는 정보시스템 사용 환경에서 SERVQUAL을 정보시스템 부서가 제공하는 서비스에 대한 측정도구로 활용하기 위해, 기존 마케팅 중심의 서비스 범주에서 벗어나 정보시스템 환경에 적용 가능한 모델을 개발하고 그 신뢰도와 타당성을 확인해보았다. 그 결과, 서비스 품질의 향상은 시스템과 정보 품질 등을 향상시킴으로 조직 구성원이 업무환경에 대해 만족하게 되고 결국 순차적으로 정보시스템을 이용하고자 하는 협업성과에 영향을 미치는 것으로 분석되었다.

• Tribology and Lubricants
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• 제35권2호
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• pp.99-105
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• 2019

This study presents an experimental investigation of the wear and oxidation of the bristles of a brush seal in a super-heated steam environment. We construct a model reflecting normal force and radial interference to predict the amount of wear. To monitor the volume loss of the bristle induced by the swirl phenomenon of the rotor, we measure the clearance between the rotor and the brush seal by using a non-contact 3-D device. We calculate the area by using the area-wise measurement method. Considering the obvious brush seal wear variables, we use two disks with different roughness($Ra=0.1{\mu}m$ and $100{\mu}m$) to determine the effect of roughness on wear. Considering an actual steam turbine, we utilize a steam generator and super-heater to generate a working fluid (0.95MPa, 523.15K) that has high kinetic energy. We observe the abrasion of the bristles in the hot steam environment through a scanning electron microscope image. This study also conducted energy dispersive X-ray (EDX) analysis for a qualitative evaluation of local chemistry. The results indicate that the wear and elimination of bristles occur on the disk with high roughness, and the weight increases due to oxidation. Furthermore these results, reveal that the bristle oxidation is accelerated more under super-heated steam conditions than under conditions without steam.

• 청정기술
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• 제20권2호
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• pp.171-178
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• 2014

이 연구에서는 대형 주물공정 용접작업장 근로자들의 건강보호 및 작업환경 개선을 위해 위해인자 조사 및 분석작업을 수행하였다. 또한, 대상 작업장의 작업환경을 개선하기 위해 측정 및 전산유체해석 모델링을 수행한 후 효과적인 환기방법을 제안하였다. 대형 주물공정 용접작업장 근로자들의 건강 위해인자를 조사한 결과, A사는 산화철분진, B사와 C사는 용접흄, D사는 용접 흄과 산화철분진이 주오염원인 것으로 확인되었다. 작업자 호흡영역에서의 흄 농도는 $0.05{\sim}4.37mg/m^3$이었고, 용접작업장 공기 중 흄 농도는 $0.13{\sim}7.54mg/m^3$이었다. 또한, 용접작업 시 최적의 환기방법을 제안하기 위해 측정 및 전산유체해석 모사를 수행한 결과, 배기공정의 경우에는 배기 덕트를 용접점에 근접시켜 국소배기를 실시하는 것이 효과적인 것으로 나타났다. 급기공정의 경우에는 개구부 끝 부분에서 급기를 하며 급기용 팬은 작업 공간 외부에 설치하는 것이 효과적일 것으로 나타났다. 향후 대형 주물공정 용접작업장의 터널형 반밀폐 공간에 대한 환기방법을 표준화한다면 주물산업 및 조선업 등에 종사하는 용접 근로자들의 건강보호 및 작업환경 개선에 매우 효과적일 것으로 판단된다.

• 대한인간공학회지
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• 제32권4호
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• pp.321-331
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• 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.