• 한국수소및신에너지학회논문집
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• 제18권4호
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• pp.374-381
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• 2007

In order to verify the feasibility of expansion of back-fire limit equivalence ratio in the hydrogen-fueled engine with external mixture, the characteristics of performance and combustion are experimentally analyzed with change of intake/exhaust valve timings under the fixed valve overlap period of $0^{\circ}$ CA(non-valve overlap period). These characteristics are also tested for the change of exhaust valve closing timing while intake valve opening timing is fixed to clear the main cause of back-fire occurrence. As the results, the less valve overlap period center is retarded, the more back-fire limit equivalence ratio increases and back-fire does not occurred after TDC. In addition, it was shown that the control of back-fire is dependent on intake valve opening timing than valve overlap period.

• 한국수소및신에너지학회논문집
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• 제18권3호
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• pp.348-355
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• 2007

To grasp a feasibility of back fire control by valve overlap period, back fire limit equivalence ratio was estimated with valve overlap period which has the same supply energy and positive intake pressure as valve overlap period $300^{\circ}\;CA$. As the result, it was shown that the smaller valve overlap period has the higher back fire limit equivalence ratio under valve overlap period $300^{\circ}\;CA$ as well as VOP $0^{\circ}\;CA$. This result means that expansion of back fire equivalence ratio by decreasing valve overlap period was caused by decrease of back flow duration of flame from in-cylinder to intake port than decrease of lower supply energy.

• Journal of Forest and Environmental Science
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• 제38권4호
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• pp.219-228
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• 2022

This study examined the relationship between the number of forest fires and days with no rainfall based on the national forest fire statistics data of the Korea Forest Service and meteorological data from the Open MET Data Portal of the Korea Meteorological Administration (KMA; data.kma.go.kr) for the last 30 years (1991-2021). As for the trend in precipitation amount and non-rainfall days, the rainfall and the days with rainfall decreased in 2010 compared to those in 1990s. In terms of the number of forest fires that occurred in February-May accounted for 75% of the total number of forest fires, followed by 29% in April and 25% in March. In 2000s, the total number of forest fires was 5,226, indicating the highest forest fire activity. To analyze the relationship between regional distribution of non-rainfall periods (days) and number of forest fires, the non-rainfall period was categorized into five groups (0 days, 1-10 days, 11-20 days, 21-30 days, and 31 days or longer). During the spring fire danger season, the number of forest fires was the largest when the non-rainfall period was 11-20 days; during the autumn fire precaution period, the number of forest fires was the largest when the non-rainfall period was 1-10 days, 11-20 days, and 21-30 days, showing differences in the duration of forest fire occurrence by region. The 30-year trend indicated that large forest fires occurred only between February and May, and in terms of the relationship with the non-rainfall period groups, large fires occurred when the non-rainfall period was 1-10 days. This signifies that in spring season, the dry period continued throughout the country, indicating that even a short duration of consecutive non-rainfall days poses a high risk of large forest fires.

• Journal of Forest and Environmental Science
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• 제32권2호
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• pp.149-157
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• 2016

Understanding regional characteristics in forest fire occurrence is important to establish effective forest fire prevention policy in Korea. This study analyzed the characteristics of forest fires occurred in 16 administrative districts for recent 25 years (1990~2014) to examine regional characteristics in forest fire occurrence. Forest fire occurrence reflects regional characteristics depending on climatic factors as well as region's society-cultural factors. Results showed that the first cause of forest fire occurrence was carelessness by human activities throughout all administrative districts, however, the second cause depends on regional characteristics. As the results of forest fire occurrence period analyzed for 10 days, the most forest fires occurred in the southern region during January to March, while forest fires in the northern region occurred mostly during March to April. We classified forest fire occurrence patterns into three types (centralized: Gyeonggi-do, dispersal: Busan, horizontally distributed: Gyeongsangnam-do) by multi-temporal analysis for forest fire occurrence period.

• 한국안전학회지
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• 제30권1호
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• pp.137-143
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• 2015

Fire fighter are exposed to the situations which are hard to predict due to continuous and accidental changes which hinder their fire fighting activity. As these threats of safety accident act as fear factors, they are doing insecure fire fighting activities. Therefore, as unclear and abnormal risks of working environment such as the riskiness of expansion of disaster, instability, obstacles of activities, abnormality, urgency, etc. increase, safety accidents are caused. This study analyzes the actual condition of safety and health and awareness of fire fighter who are exposed safety accidents during their fire fighting activities and utilize such result as the basis data to secure safety of fire fighter, keep efficient safety control and prevent accidents. The results of analysis are as follows. As rescue works among all fire-fighting works shows the highest emotional stabilization and the highest post-traumatic stress disorder is shown in fire sergeant level positions, and fire fighters whose working period is 10-15 years, reinforcing safety training to long-term workers is necessary. As the result of survey regarding safety awareness, the highest awareness level was shown in fire sergeant level positions, and fire fighters whose working period is over 20 years, and when it comes to operation of fire fighting equipments, fire-fighting workers and workers having 1-4 years of working period showed high safety awareness. The more serious injury in a fire fighter experienced as the first injury after working as a fire-fighter, the more cause-and-effect relationship was shown between personal physical condition and work, and it is shown as obstacles of fire fighting activities and affects to post-traumatic stress disorder. Moreover, as after-work off duty activities also affect to official disaster, systematic improvement of working environment is required. Occupational medical work compatibility evaluation considering the distinct characteristics of works to secure fire-fighter' health care together with fire-fighting capability is shown to be necessary.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 1997년도 International Symposium on Fire Science and Technology
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• pp.477-483
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• 1997

Experiments have been performed to investigate the formation of smoke layer in case of several furniture fires such as trashcan, chair, carpet, sofa, mattress, and wardrobe in a residential room. As a result of the present investigation, the uniformly distributed fire of carpet showed that the ignition and the initial growth period were relatively short while the fully developed period was considerably long. The concentrated fires such as mattress and wardrobe showed that the ignition and the initial growth period were relatively long. The descending time of the interface heights was within 1-3 minutes to reach around 1m. However, the interface height was lowered to 0.25-0.75m above the floor at the time of the maximum temperature.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 1996년도 학술발표회
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• pp.24-29
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• 1996

The objective of this research is to study on the formations of thermal stratification in a room in case of several furniture fires such as trashcan, chair, carpet, sofa, mattress and wardrobe as a fire starter in a residential room by performing the experimental studies. The uniformly distributed fire in case of carpet showed that the ignition and the initial growth period were relatively short while the fully developed period was considerably long. The concentrated fires such as the mattress and wardrobe showed that the ignitions and the initial growth periods were relatively long. When fire spread to only one direction, like the case for the trashcan with a regular shape, there was one peak of temperature profile, and for the irregular shaped furniture such as chair, sofa, mattress and wardrobe, there were two or more peaks. The interface heights for the furniture fires were around 1(m) mataining constant state. However, at the time of the maximum temperature, the interface height was lowered to 0.25(m)-0.75(m) from the floor

• 한국화재소방학회논문지
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• 제2권1호
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• pp.3-10
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• 1988

Concrete is incombustible and has good fire resisting properties, i. e. when exposed to fire it continues to perform satisfactorily for a reasonable period of time. Nevertheless, with time and high temperature gradient, brought about the fire, causes cracking and spatting. Further deterioration and loss of strength are caused by gradual dehydration of concrete paste. This paper is aimed to make a proposal for the design and construction of reinforced concrete structures with more sufficent resistance to fire by the theoritical analysis, which is base4 on investigation of general damages by the fire and change of properties on concrete influenced by high temperature.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 2001년도 추계학술대회 논문집
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• pp.109-113
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• 2001

• 한국방재학회 논문집
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• 제2권1호
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• pp.161-167
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• 2002

전국단위로 시행되고 있는 산불위험시기가 전국 9개 지역(강원, 경기, 경남, 경북, 전남, 전북, 제주, 충남, 충북)과 차이가 있는지를 알아보기 위하여 산불발생건수와 피해면적을 가지고 순기별로 구분하여 상관분석을 실시하였다. 분석 결과 산불발생건수에서는 모든 지역에서 유의성이 있는 것으로 나타났고, 산불피해면적에서는 경남, 제주와 유의성이 없는 것으로 나타났다. 이에 전국을 대상으로 모든 지역을 설명하기에는 부족하므로 전국 9개도를 대상으로 하여 산불위험시기를 구분하기 위하여 산불발생과 피해면적을 이용하여 분산분석의 다중검정을 실시하고 순기별로 유의성 검정을 실시하였다. 그 결과 산불발생에 있어서 제주를 제외한 지역에서 1% 유의성이 있었고, 산불피해면적은 강원, 제주를 제외한 지역에서 1% 유의성을 보였다. 각 지역별로 위험시기를 구분할 수 있지만 행정적 효율성을 높이기 위하여 지역별 상관분석 결과를 이용하여 산불위험시기가 비슷한 중부권(강원, 경기, 경북, 전북, 충남, 충북), 남부권(경남, 전남), 그리고 제주권(제주)으로 분류하였다. 산불발생시기에 있어서는 중부권은 2월중순${\sim}$5월상순까지 전체의 81%가 발생한 반면 남부권은 1월하순${\sim}$4월중순까지 전체의 71%가 발생하였다. 산불피해면적에 있어서는 중부권은 2월중순${\sim}$5월상순까지 전체의 98% 가 발생한 반면 남부권은 1월하순${\sim}$4월중순까지 전체의 82%가 발생하였다.