• 한국안전학회지
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• 제17권4호
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• pp.45-51
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• 2002

In this study, the fracture characteristics of carbonized silicon grinding wheels were examined with tensile, compression, impact and bending test. The experiment was performed for the various grinding wheels with grain size #46, #80, and grade H, L, P, and one vitrified bond and one structure No.7. Also the centrifugal fracture rpm of carbonized silicon grinding wheels were measured and compared with the calculated values for the various wheel diameters and thicknesses. The results showed that the fracture tensile strength was $1.5~2.0Kg_f/mm^2$, and it was increased by decreasing grain size and increasing grade. The fracture compression loads were $1,600~3,000Kg_f$, and the inner stress was higher than outer's. And the absorption energy of impact test was 3.3~4.7 J, and it was increased by decreasing grain size but it was not effected by grade. The fracture bending stress was $0.1~0.2Kg_f/mm^2$, and it was increased by decreasing grain size and increasing grade. The centrifugal fracture rpm of carbonized silicon grinding wheel was about 8,500~12,000 and agreed well with the calculated value, and it was increased by decreasing diameter. However, it was almost constant for the reduction of wheel thickness.

• International Journal of Safety
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• 제11권2호
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• pp.29-37
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• 2012

Since most construction workers comprehend information on work through sight, the importance of safety signs are increasing by the day. In Korea, due to the sharp economic progress and the higher standard of the workforce, since the end of 1980, each year the number of foreign workers entering the country who working simple technical jobs have increased this condition. This study researched safety signs, which are the final accident prevention measures at the workplace. Based on the study, comprehension of the standard safety signs of the Occupational Safety and Health Act (OSHA) was lacking at a level of 2.5. Also, the perception level of the Industry Public Safety Law (38%) was very low. And, it was found that sex and experience or non-experience in safety training was not an issue in the level of understanding. However, when satisfying the standards of the Occupational Safety and Health Act and changing the safety signs, the level of understanding went up to 3.49 and the perception level was increased significantly to 70%. Thus, it is concluded that, since the foreign workers are mainly from non-English speaking countries and because the workers of Korea are not familiar with English, in order to provide proper safety information, there must first of all be simplistic and concise pictograms. This will provide needed information and must be coupled with simple English words that can give additional information to the worker and be effective in helping him understand and perceive the safety sign. Also, it has been determined that the existing forms of safety signs and their effectiveness in industry accident prevention must be reassessed.

• Biomolecules & Therapeutics
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• 제25권6호
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• pp.659-664
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• 2017

Although lisdexamfetamine is used as a recreational drug, little research exists regarding its potential for dependence or its precise mechanisms of action. This study aims to evaluate the psychoactivity and dependence profile of lisdexamfetamine using conditioned place preference and self-administration paradigms in rodents. Additionally, biochemical techniques are used to assess alterations in the dopamine levels in striatal synaptosomes following administration of lisdexamfetamine. Lisdexamfetamine increased both conditioned place preference and self-administration. Moreover, after administration of the lisdexamfetamine, dopamine levels in the striatal synaptosomes were significantly increased. Although some modifications should be made to the analytical methods, performing high performance liquid chromatography studies on synaptosomes can aid in predicting dependence liability when studying new psychoactive substances in the future. Collectively, lisdexamfetamine has potential for dependence possible via dopaminergic pathway.

• 한국화재소방학회논문지
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• 제32권5호
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• pp.112-121
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• 2018

본 연구는 소방기술사(Fire Professional Engineer)의 안전의식, 안전행동과 인명안전의 관계를 검증하기 위하여 기술통계 분석, 요인 분석, 신뢰도 분석, 상관관계 분석을 실시하였으며, 연구가설을 설정하여 단순회귀 분석, 3단계 매개회귀분석을 실시하였다. 분석 결과, 소방기술사의 안전의식이 높아지면 안전행동은 72.1% 상승하고, 안전의식과 안전행동이 높아지면 인명안전은 각각 61.5%와 64.5%가 상승하는 것으로 나타났다. 또한 안전행동은 안전의식과 인명안전의 관계에서 부분매개효과가 나타났다. 모든 연구가설(H1, H2, H3, H4)의 채택으로 소방 관련법은 인명안전 중심으로 개정되어야 한다는 필요성이 통계적으로 검증되어, 향후 인명안전을 반영한 분석 자료로 널리 활용 될 것이다.

• Biomolecules & Therapeutics
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• 제1권2호
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• pp.160-165
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• 1993

The effects of Glycyrrhizae Radix (GR) on the metabolism of acetaminophen (AA) were examined in male Sprague-Dawley rats. The methanol extract of GR (500 mg/kg) was administered orally to rats for 6 days. AA and its metabolites excreted in bile, urine and blood within 120 min after dosing of AA (150 mg/kg, i.v.) were assayed by HPLC. Treatment of rats with the methanol extract of GR significantly increased the cumulative biliary excretion of AA-glucuronide (156% of the control) and decreased that of AA-sulfate (63% of the control). The cumulative urinary excretion of AA-glucuronide was also significantly increased to 132% of the control. GR treatment significantly increased total (biliary plus urinary) excretion of AA-glucuronide (172% of the control) without influencing thioether and sulfate conjugates of AA. The results clearly show that GR enhances UDP-glucuronosyl transferase-mediated detoxication of AA, but may not influence sulfotrans-ferase-mediated and cytochrome P-450-mediated metabolites formation.

• 한국기계가공학회지
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• 제19권10호
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• pp.68-73
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• 2020

The proportion of airline accidents caused by human factors is steadily increasing. The aviation industry has made considerable progress in reducing the accident rate; however, since the early 1980s, the accident rate has remained constant. Due to airspace congestion, the safety margins of these existing safety promotion methods are gradually decreasing; thus, new methods to prevent accidents and quasi-accidents must be devised. Causative factors of aviation accidents include increased air traffic due to increased air demand, increased cumulative working hours due to long-distance flights, and complicated flight environments. Accidents often occur when several small errors accumulate in the normal course of operation, rather than after a single error. Accordingly, in this study, the impacts on air navigation due to human error by aviation maintenance personnel and varying international standards (i.e., KOCA vs. F.A.A vs. EASA) analyzed, and the relationship between human decision-making and behavior was investigated. The resulting safety analysis and alternatives were presented to prevent aviation maintenance accidents and cognitive ergonomics errors.

• 비파괴검사학회지
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• 제24권5호
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• pp.487-493
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• 2004

본 연구는 고효율 비접촉 초음파 송수신이 가능한 미세가공 정전용량형 초음파 탐촉자(cMUT)를 개발하기 위한 기초연구로 수행되었다. cMUT의 주요 구성요소인 미세 진동 막의 거동-총진 주파수, 막 변위, 막 붕괴 변위, 막 붕괴전압-을 이론적인 해석과 유한요소해석을 이용하여 분석하였다. 진동 막의 두께와 크기, 희생층 두께, 전극의 두께와 크기 등과 같은 cMUT의 설계인자를 검토하였다. 분석결과 진동 막의 공진주파수는 진동 막의 두께가 증가함에 따라 증가하였으며 직경에 따라서는 감소하였다. 직류 바이어스 전압이 증가함에 따라 진동 막의 변위는 증가하였으며 진동 막의 붕괴전압을 분석하였다.

• 전기학회논문지P
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• 제65권4호
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• pp.242-249
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• 2016

The railway system is being converted to the computer system from the existing mechanical device, and the dependency on software is being increased rapidly. Though the size and degree of complexity of software for railway system are slower than the development speed of hardware, it is expected that the size will be grown bigger gradually and the degree of complexity will be increased also. Accordingly, the validation of reliability and safety of embedded software for railway system was started to become influential as the important issue. Accordingly, various software test and validation activities are highly recommended in the international standards related railway software. In this paper, we presented a software coding analysis tool using symbolic execution for railway system, and presented its result of implementation.

• 한국안전학회지
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• 제21권4호
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• pp.55-59
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• 2006

The radiation effects on electrical and mechanical properties of LDPE/EVA blends with various vinyl acetate contents were investigated. Radiation degradation of LDPE/EVA blends were studied by using gelation, volume resistivity, permittivity, dissipation factor, elongation at break, and E-modulus. As vinyl acetate contents increased in LDPE/EVA blends, electrical insulation characteristics were deteriorated, but flexibility was improved. As irradiation doses increased, electrical insulation characteristics were improved, but flexibility was deteriorated.

• 한국안전학회지
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• 제22권2호
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• pp.1-7
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• 2007

A problem of a unsteady time-dependent flow in a channel is of practical importance and widely considered in the design of devices such as heat exchangers, duct, and electronic equipments. The characteristics of fluid flow in channel with oscillating vortex generator was investigated experimentally. The main object of this study was to investigate the effect of the excited frequency, the excited amplitude, and Reynolds numbers on the generated frequency. Flow patterns were visualized using smoke generator and generated frequencies were measured using hot wire anemometer. When the excited frequency is increased, excited amplitude decreased and Reynolds number increased, the strength of PSD of generated frequency is decreased.