• 한국소음진동공학회논문집
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• 제17권3호
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• pp.241-248
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• 2007

A study has been conducted to investigate the subjective responses of loudness and annoyance according to the exposed time of urban traffic noise in controlled laboratory environment. To make a closer inspection into psychological response relevant to noise characteristics while varying the time of exposure to noise, the subjects were presented a set of noises with different exposed time and requested to judge spontaneously on a 100-unipolar scale. To be concrete, the subjects were exposed to noises being varied in time from 15 sec up to max. 1,200 sec for the controlled traffic noise sources. So far achieved from laborious tests, it has an importance being on the logarithmic relations of perceived loudness and exposed time, say, it is more increased the perceived loudness in the sorter exposed time than in the longer exposed time. However, the trend is said to be not effective for the case of annoyance. On the other hand, the subjective impressions on relative annoyance of noise is shown to be correlated with the noise characteristics such as loudness (sones), tonality and time with logarithmic scale, the product correlation moment being calculated as $R^{2}=0.99$. The variances to be explained for annoyance assessments through varying the time of exposure were ranged between 30 % and 50% for the exposed time, $27{\sim}37%$ for tonality, and $34{\sim}20%$ for loudness, respectively With these results, hopefully, it can be helpful for those who want to work out an experimental design for evaluating an environmental noise or to quantify any psychological dimensions found in annoyance assessments.

• 한국안전학회지
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• 제17권3호
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• pp.56-60
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• 2002

The purpose of this study was to present the thermal characteristics of the working uniform exposed to the radiation heat. The effect of exposure time and exposure distance on the changes and the relationship between physical properties were investigated experimentally. Regardless of the kind of working uniform, the surface temperature of the working uniform with exposed time sharply increases as exposed distance is more close and the reaching time of steady state is shorter. The surface temperature of working uniform exponentially decreases as exposed distance become more distant. For the safety of the working man, it is necessary that he work far away at a fixed standard distance from the radiant heat source.

• Journal of Preventive Medicine and Public Health
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• 제26권2호
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• pp.210-221
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• 1993

In order to evaluate the confounding factors of neurobehavioral tests and the neurobehavioral effects in the workers exposed to organic solvents, NCTB was carried out on 100 workers. 46 workers had never been exposed to neurotoxic substances, and the others were being exposed to the solvents, mainly toluene. Simple reaction time, digit symbol, Santa Ana dexterity test and persuit aiming were different with age in non exposure group. Simple reaction time was carried out well in males, and digit symbol and persuit aiming were in females. There was no difference at educational level when the subject was educated over 12 years. Santa Ana dexterity and Benton visual test differed according to exposure level to toluene, however simple reaction time didn't. The acute neurotoxic effect was not excluded in this study. But, NCTB could be used to evaluate and prevent neurobehavioral changes in workers exposed to neurotoxic solvents in Korea.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.1431-1438
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• 2007

This paper presents a refined design model for current railroad design code on concrete structures exposed to marine environment. A time-varying diffusion coefficient(D) as well as surface chloride$(C_S)$ and chloride threshold level$(C_{lim})$ are studied. Averaging value of the D with time over exposed duration were used to refined durability design model to consider time dependent characteristic of D. The values for $C_S$ and $C_{lim}$ for the seashore in Korea revised for realistic durability design. The proposed model was verified by the so-called performance-based durability design, which is widely used in recent durability design code. Results show that the current standard specification underestimates durability performances of concrete structures exposed to marine environment, so that the cover depth design using current durability evaluation in the standard specifications is very much conservative. Thus, it is found that proposed durability design models for the railroad design code for railway concrete structures can be used effectively for service life design of concrete structures in marine environment.

• Journal of the Korean Wood Science and Technology
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• 제32권5호
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• pp.66-74
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• 2004

내화 성능은 표준 화염 조건에 노출된 목구조물의 안전성 평가를 위한 중요한 기준이 된다. 내화 성능의 기준으로 여러 나라에서 지속 시간과 파괴 시까지의 시간이 사용되고 있다. 본 연구에서는 화염에 대한 신뢰성 설계의 기초 연구로서 화염에 노출된 목재 마루 시스템의 신뢰성 해석이 진행되었다. 해석은 수치 해석적 방법과 결정론적 방법 두 가지를 모두 사용하였다. 두 방법 간에는 큰 차이를 보이지 않았다. 화염에 노출된 마루시스템의 신뢰도는 부재의 변이계수에 크게 의존하였으며 부재의 강도나 하중은 신뢰도에 크게 영향하지 않았다.

• 한국화재소방학회논문지
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• 제17권1호
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• pp.21-25
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• 2003

본 연구에서는 복사열에 노출된 소방용 방수복의 열적 특성에 대한 실험을 수행하였다. 실험결과 소방용 방수복의 노출시간에 따른 표면의 온도상승은 노출거리가 가까울수록 급격히 일어났다. 또한 복사열유속이 클수록 표면의 온도가 높으며, 정상상태 도달시간은 짧게 나타났다. 소방용 방수복의 노출거리가 멀어질수록 표면의 온도는 급격히 감소하며, 전면과 후면의 온도차도 감소하였다. 복사열유속이 증가할수록 안전노출거리가 증가하였다. 따라서 소방대원의 안전을 위해서는 복사열원으로부터 일정거리이상 떨어져 작업하여야 할 것으로 사료된다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2016년도 춘계 학술논문 발표대회
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• pp.164-165
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• 2016

To express the original texture of the concrete, exposed concrete finishing technique has been applied in many buildings. However, it is likely to cause quality problems after construction is completed. In addition, because of costs and time issues, reconstruction and maintenance works are difficult and ineffective. Therefore, step-by-step proactive quality management based on sufficient consensus among participants(client, designer, contractor) is very importatnt. This study analyzed factors causing low quality exposed concrete and quality contol points applied to 'A' headquarter construction project.

• 대한기계학회논문집A
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• 제26권12호
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• pp.2662-2669
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• 2002

Recently structural applications of adhesive bonding method have been increased extensively in automobile industry. Adhesively-bonded joints which are used in automobile field are exposed to various environmental conditions. In this study, several environmental factors were concerned to evaluate their effects on the adhesive strength such as air temperature, water temperature, exposed time in water. The specimens are exposed for 1, 10 and 100 hours at various air temperatures to evaluate the effects of the air and water temperature on the adhesive strength. It is proved that the adhesive strength decrease with rising the air and water temperature, and the adhesive strength decrease steeply at the higher temperature with increasing the exposure time in water.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.1444-1451
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• 2010

This paper aims for proposed the deflection limit on vibration serviceability of high-speed railway bridges considering the exposed time duration when a train passes a railway bridge. For this purpose, bridge-train transfer function was derived and bridge-train interaction analysis was performed by using the derived function. The vertical acceleration signals of passenger cars obtained from bridge-train interaction analysis were compared with them from the bridge-train transfer function by moving constant force analysis. Therefore it was estimated possible to induce the comfort deflection limit of railway bridge by using bridge-train transfer function. The deflections by moving force of single span bridge and continuous bridge were assumed as sine and haversine wave. The deflection limit on vibration serviceability of high-speed railway bridges considering the exposed time duration can be expanded using bridge-train transfer function and bridge comfort limit considering serviceability due to bridge vibration. And it was compared to other allowable deflection limits of railway bridge design specifications.

• Computers and Concrete
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• 제20권2호
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• pp.185-196
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• 2017

Durability problems initiated from steel corrosion are unseen but critical issues, so that many researches are focused on chloride penetration evaluation. Even if RC (Reinforced Concrete) structures are exposed to normal environment, chloride ingress varies with concrete surface conditions and exposed period. This paper presents an analysis technique for chloride behavior evaluation considering time effect on diffusion and surface conditions assumed as double-layered system. For evaluation of deteriorated surface condition, field investigation was performed for concrete pavement exposed to deicing agent for 18 years. In order to consider enhanced surface concrete, chloride profiles in surface-impregnated concretes exposed to chloride attack for 2 years from previous research were investigated. Through reverse analysis, effectively deteriorated/enhanced depth of surface and the related reduced/enlarged diffusion coefficient in the depth are simulated. The proposed analysis technique was evaluated to handle the chloride behavior more accurately considering changes of chloride ingress within surface layer and decreased diffusion coefficient with time. For the concrete surface exposed to deicing agent, the deteriorated depth and enlarged diffusion coefficient are evaluated to be 12.5~15.0 mm and 200% increasing diffusion coefficient, respectively. The results in concrete containing enhanced cover show 10.0~12.5 mm of impregnated depth and 85% reduction of chloride diffusion in tidal and submerged conditions.