• Magazine of the Korea Concrete Institute
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• v.10 no.1
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• pp.143-151
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• 1998

최근들어 반복하중에 의한 철근콘크리트 구조물의 손상이 자주 발견되고 있으며 교량 등의 구조물 등은 때때로 과적차량에 의한 초과하중을 받아 이러한 피로손상이 심화되고 있다. 본 연구에서는 이러한 반복 하중을 받는 철근 콘크리트보의 누적피로손상에 대한 실험적 연구룰 수행하여 피로하중에 의한 철근콘크리트보의 손상과정을 규명하였다. 실험 변수를 전단철근의 양과 반복되는 하중의 크기 및 반복횟수로 하여 실험부재를 제작하였으며, 하중제어에 의한 휨시험법에 의해 3Hz의 반복하중을 시편에 재하하였다. 사인장 균열하중과 사인장 균열 후 반복하중에서의 보의 손상누적거동 즉 처짐. 전단철근의 변형도, 에너지 손실 등의 변화를 실험적으로 평가하였으며, 이를 통하여 반복하중에 의한 누적손상에 의해 철근 콘크리트보의처짐 및 전단변형도가 초기하중상태에서는 급격히 증가하다가 이후 점진적으로 증가하는 것을 규명하였다. 본 연구의 결과는 사용하중상태에서 점진적으로 발생할 수 있는 피로손상의 누적과정을 기술하여 주고 있다.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2001.11a
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• pp.135-136
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• 2001

최근 들어 서울을 포함한 수도권지역에서의 오존농도가 증가함에 따라 대기환경기준치를 초과하는 횟수가 늘어나고 있는 추세이다. 이에 따라 오존농도를 저감하기 위해 많은 관심을 가지고 있다. 오존농도는 일출이 시작되면서 광화학반응을 통해 생성되는데, 점차 일사강도가 강해지면서 일사량이 강한 오후 2-3시경에 보통 최고 오존농도를 나타낸다. 그러나 최근 들어 일최고 오존농도는 오히려 오후 2-3시보다 그 이후인 4-5시 심지어 오후 6-7시에 일최고 오존농도를 나타내기도 한다. (중략)

• Proceedings of the Korea Contents Association Conference
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• 2013.05a
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• pp.89-90
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• 2013

공항서비스 질에 대한 이용객의 인식이 전반적인 공항이용의 매력도와 직결되므로 그 중요성이 점점 커지고 있다. 반면 현 제주국제공항은 활주로의 수용능력도 부족 할 뿐만 아니라 여객 터미널의 수용 능력, 운항 횟수 20만 초과 할 것으로 예상하고 있다. 또한 2011년 11월 11월 NEW7WONDERS에서 7대 자연경관으로 선정됨으로서 세계화, 개방화 그리고 관광객 증가에 따른 항공 수요 증가 추세이다. 공항산업이 빠르게 변화하고 있고 제주지역 발전 속도에 따른 장래 항공수요를 감안하여 제주국제공항의 시설에 대한 기대수준과 만족수준을 측정해야 한다. 따라서 본 연구는 공항의 독특한 서비스 환경에 대한 공항이용객들의 기대 역할 실증연구를 통해 기대와 만족간의 차이분석 연구를 하는데 목적이 있다. 제주국제공항 이용객들을 대상으로 설문조사를 실시하였고 이용객들이 기대하는 공항서비스 품질은 무엇인지를 분석하였다. 향후 공항서비스 품질관리에 관한 개선사항을 제시할 수 있는 기초자료로 활용되고자 한다.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2023.11a
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• pp.335-336
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• 2023

최근 환경에 대한 관심이 지속적으로 증가함에 따라 실내 공기질에 대한 관심 역시 증폭되었다. 이에 따라 실내 공기질을 결정 짓고 흡연에 이어 폐암 사망률이 높은 라돈에 대한 관심 역시 증가하였다. 따라서 본 연구에서는 실내 라돈가스의 농도를 낮추기 위한 방법을 찾기 위해 RADON EYE RD200을 이용하여 교육연구시설에서의 세 강의동을 대상으로 라돈 방출량을 측정하고, 환기를 통해 라돈의 감소량을 측정한다. 세 강의동 모두 현재 기준치인 148 Bq/m³을 초과하는 수치를 기록하였고, 강의실을 10분간 환기한 결과 1회 환기 시 평균 77 Bq/m³만큼 감소하였고, 2회 환기 시 평균 56 Bq/m³만큼 감소하였다. 본 연구를 통해 라돈의 실태 및 위험성을 인지하고 라돈에 관련된 시설물 지침 및 환기를 강조하는 방안에 대한 마련이 필요하다고 판단된다.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.4
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• pp.51-58
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• 2008

Purpose: This study was assessed to investigate adverse effect induced by overuse of disposable soft contact lenses (CL). Methods: Three disposable lenses (etafilcon A, hilabilcon A, and nelfilcon A) were applied to 19 normal subjects free from any eye diseases for either a single day or variable periods by when subjects complained any discomforts. On the first and last days, localizations of lens' center on corneal surface and blink rates were recorded at every case. Results: Among CL wearers, 10.5% and 47.4% of total subjects quit wearing on the second day and third day, respectively. The case of stopping disposable lens wear was continuously increased with extended hour of lens application. On fourth day, 70.2% of CL wearers reported severe discomforts such as redness, dryness, irritation, pain and blurred vision. When subjects stopped CL wear, decentration of lens from the center of cornea was observed when it compared to the case of single usage of disposable CL. Also about 80% of total subjects showed increased blink rate when CL were worn for more than 2 days. These changes in lens centration and blink rate were consistantly shown regardless of lens types. Conclusions: Blurred vision and acute/chronic discomforts could occur to CL wearers by decentration of lens and increased blink rate when CL were overused more than 2 days even the numbers of two parameters measured in this study were variable by each subject or lens types. Therefore, consideration of individual characteristics and lens types is critical to prevent adverse effects may induced by overusage of disposable lens.

• Journal of Korean Society of Forest Science
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• v.108 no.3
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• pp.341-348
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• 2019

In order to reduce the safety risk of forestry operations, this research was conducted to examine the suitability of chainsaw protective pants after repeated laundering, testing four different products that are currently used in hand-held chainsaw operations. Laundering was repeated 10, 20, 30, 40, and 50 times. After washing, we measured the shrinkage ratio of 17 measurement positions mostly affecting the safety of forest operations and suggested the expected safety life cycle of chainsaw protective clothes. The results showed that most of the products have only one measurement position where the standard shrinkage ratio (<6%) was exceeded after 20 washings, and that the lateral direction of measurement positions shrank more than the vertical one. The numbers of repeated launderings and measurement positions were found to be significant factors influencing the shrinkage ratio (p<0.05). In the shrinkage rates for 17 measurement positions, there were significant correlations between five of the measurement positions (a, b, g, j, and n) and the number of repeated launderings (p<0.05). Therefore, the results suggest that about 10 months would be suitable for an adequate safety lifetime for chainsaw protective pants. The relationship between the number of repeated launderings and the measurement positions will be further analyzed in detail to examine the durability of chainsaw protective pants.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.46 no.3
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• pp.77-85
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• 2009

Execution times of tasks can be variable depend on input data. If we choose a high performance processor to satisfy the worst case execution times, the hard cost becomes high and the energy consumption also becomes large. To apply a lower performance processor, we have to utilize processor capacity maximally while overrunning tasks can not affect deadlines of other tasks. To be used for such systems, this paper presents SBP (Shared Bandwidth Partitioning) that a processor bandwidth is reserved and shared among all tasks. If a task needs more processor capacity, it can use a portion of the shared bandwidth. A simulation result shows that SBP provides better performance than previous algorithms. SBP reduces deadline miss ratio which is related to scheduling quality. And the number of context switches, which is related to system overhead, is also reduced.

• Environmental and Resource Economics Review
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• v.18 no.4
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• pp.767-785
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• 2009

This paper studies the effect of industrial waste water effluent charge reform. The goal of the present effluent charge system is to use environmental resources in an efficient way by charging the cost for removing emitted water pollutants. However, the present system is a type of regulation instead of providing economic incentives to the industry. That is, if a firm emits pollutants greater than the limit, it has to pay an amount greater than the cost of cleaning them taking into account the amount of waste water discharged, region, the number of violation and the level of density of pollutants. However, the excessive fees have resulted in the lowest ratio of revenue-to-effluent charge among all environmental charges. The paper estimates the effect of the change in effluent fee and revenue when the present effluent charge system is converted to one that offers economic incentives. The results show that the amount of waste water effluent charge is about four times larger than the estimated environmental cleaning cost. In addition, the results show that by modifying the effluent charge system, the ratio of revenue to effluent charge can be raised.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.6
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• pp.1-12
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• 2009

Recently, as the importance of Economical Driving has been gradually growing up, the needs for research on automatic analysis of driving patterns that will ultimately provide drivers the methods for Economical Driving have been increasingly risen. Based on this purpose, we have executed two things in this paper. First, we have collected overall driving information such as date, distance, driving time, speed, idle time, sudden acceleration/deceleration count, and the amount of fuel consumption. Second, we have analyzed the influences of driving patterns on economical driving by employing the data mining techniques. These results can be applied in preventing bad driving patterns which will have consequently bad effects on Economical Driving in two aspects: by presenting some information on the terminal of the vehicles such as idle time, over-speed time, sudden acceleration/deceleration count continuously and by providing the drivers with alert information when the idle time ratio and the over-speed time ratio are excessive.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.345-353
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• 2020

On conventional railway lines, trains with different speeds are operated. Therefore, trains moving on curved sections with cants must accept various ranges of balanced cants, cant deficiency, and cant excess, which is essential for the comfort and safety of train operation. In this study, the correlation between the curve radius, cant, and train speed on a track was analyzed to check the cant range that satisfies the criteria of train types, operation speed, cant deficiency, and cant excess. Also, the range of setting the cant by the curve radius and balanced cant were calculated by a regression analysis of train speed according to the frequency of operation in the case of mixed trains. The results could make it possible to improve the speed of the operation route, reduce the loss of ride quality, reduce the risk of derailing caused by cant deficiency, and minimize the load deflection by excess cant. This will ensure the safety of trains running on curves and improve the efficiency of track maintenance.