• 대한기계학회논문집
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• 제18권12호
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• pp.3326-3334
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• 1994

To theoretically predict knock occurrence in S. I. engine as a function of engine design and operating parameters, transient local temperature and pressure, mixture density of flame front in combustion period are calculated. We next determined normal combustion period and auto ignition period of end gas using the prediction method on occurrence of spark knock which we suggested. We predict knock occurrence in S. I. engine by comparing consecutively normal combustion period with the auto ignition period of end gas in combustion period. Engine design and operating parameters such as compression ratio, engine speed, spark timing, inlet temperature and pressure are taken into account in this calculations. The predicted result are well matched with the experimental results in turbocharged engine. Therefore, this method will provide the systematic guideline for designing engines in view of knocking limits.

• 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.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 봄 학술논문 발표대회
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• pp.29-30
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• 2022

Tile defects in apartment houses are caused by a combination of various factors. These factors cannot be specified, and it is difficult to determine the exact cause because a number of causes are intertwined. In addition, because the climate of Korea is different by season, the coefficient of thermal expansion between materials is different, which is a major cause of tile defects. Therefore, this study analyzed the difference between the construction location and the period of defect occurrence according to the types of tile defects caused by environmental differences between indoor and outdoor environments. Two-way ANOVA was used, indoor and outdoor spaces were selected, and defect types were selected accordingly to show the difference in the occurrence period of each defect.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 가을 학술논문 발표대회
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• pp.67-68
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• 2022

The area inside the apartment building where tiles are installed is applied as a finishing material for walls and floors, including exterior walls, balconies, hallways, bathrooms, and kitchens. As it is constructed in various spaces, differences in the type and period of occurrence of tile defects may appear, which is caused by heterogeneous characteristics between materials and external causes. Therefore, in this study, two-way ANOVA was used to figure out the relationship between the defect occurrence type and the period depending on the type of tile construction in the apartment building.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2004년도 학술발표회
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• pp.479-483
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• 2004

A new calculation method of expected overtopping probability of rubble mound breakwater considering real tide occurrence has been proposed. A calculation method of expected overtopping probability of rubble mound breakwater was proposed by Kweon and Suh (2003). In their calculation, the fluctuation of tidal elevation was expressed by the sinusoidal change that yields the uniform distribution of occurrence frequency. However, the realistic distribution of tidal elevation should influence on the overtopping chance. In this study, the occurrence frequency of tidal elevation obtained from the real sea is included. The tidal elevation used in this study is collected from the east coastal part of Korean peninsular. Analyzing the annual data of the tidal fluctuation measured hourly during 355 days, the distribution of occurrence frequency is formulated utilizing by the normal distribution with one peak. Among the calculation procedures of annual maximum wave height, wave height-period joint distribution, wave run-up height and occurrence frequency of tide, only the annual maximum wave height is again chosen randomly from normal distribution to consider the uncertainty. The others are treated by utilizing the distribution function or relationship itself, It is found that the inclusion of the variability of tidal elevation has great influence on the computation of the expected overtopping probability of rubble mound breakwater. The bigger standard deviation of occurrence frequency is, the lower the overtopping probability of rubble mound breakwater is.

• 대기
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• 제18권4호
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• pp.493-506
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• 2008

In order to examine the variational features of Asian dust outbreak in recent years, observed WMO synop data were employed for the period from 1996 to 2007. We first divided Asian dust source regions into four subregions; 1) Taklamakan, 2) Gobi, 3) Inner Mongolia-Manchuria and 4) Loess, and the meteorogical variables such as wind speed, precipitation and threshold wind speed observed during the Asian dust outbreak period were compared with those during non-Asian dust period. The results showed that temporal variation of occurrence frequency of dust outbreak had a strong positive correlation with the frequency of strong wind speed and low precipitation in each of the 4 source regions. Spatial distributions of frequency of dust occurrence after 2002 showed increasing trend in Gobi and Inner Mongolia-Manchuria but decreasing trend in Loess region. This is showing a shift in main source region toward Northwest, especially since 2003.

• 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.

• 한국의사학회지
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• 제31권2호
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• pp.41-52
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• 2018

In this study, we research the tendency of medical text publication by examining the period of the great measles outbreak and the period of the publication of specialized smallpox texts. Using the National Institute of Korean History database for the Annals of Joseon Dynasty, the Daily Records of Royal Secretariat of Joseon Dynasty and Bibyeonsadeunglok, we will compare all records of measles occurrence. Measles and smallpox (Majin in Korean) have similar symptoms and treatment methods. In East Asia, when measles occurred it spread to Joseon and Japan, which are verified by records of the Annals of Joseon Dynasty, the Daily Records of Royal Secretariat of Joseon Dynasty and Bibyeonsadeunglok. The medical books related to measles are; Ryuhasinbang, Majinpyeon, Geupyubang, Yimsinyeokbang, Eulmisinjeon, Majingbang, Jinyeokbang, Magwahoetong, Majingibang, Susengsingam, Hongjinsinbang. Measles and Majin are the same disease. During the period of measles occurrence, measles-related medical books were published, and this relation of measles occurrence and measles-related medical text publication is verified by several national records.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.3311-3316
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• 2007

To analyze the influence of valve overlap period on a backfire occurrence, the single cylinder research engine with MCVVT(Mechanical Continuous Variable Valve Timing) system is developed and backfire limit equivalence ratio defined as fuel-air ratio equivalence ratio at which backfire occurs is examined according to various valve overlap period. The MCVVT is the system to control valve overlap period by mechanical device. It is estimated that the lower valve overlap period has the higher backfire limit equivalence ratio though the same energy is supplied. When the valve overlap period is changed from 30$^{circ}$ CA to 0$^{circ}$ CA, backfire limit equivalence ratio is increased 74%, approximately. It means that valve overlap period is concern in backfire occurrence, and may be one of the methods for controlling back fire occurred in a $H_2$ engine.

• 지능정보연구
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• 제18권1호
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• pp.23-38
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• 2012

온라인 쇼핑몰은 인터넷을 통해 손쉽게 접근이 가능하기 때문에, 최초 구매의사가 발생한 시점으로부터 이에 대한 실제 구매가 실현되기까지의 기간이 오프라인 쇼핑몰에 비해 비교적 짧게 나타난다. 즉 오프라인 쇼핑몰의 경우 구매희망 물품을 바로 구매하기 보다는 몇 개의 물품들을 모아서 구매하는 행태가 일반적이다. 하지만, 인터넷 쇼핑몰의 경우 단 하나의 물품만을 포함하고 있는 주문이 전체 주문의 절반 이상을 차지한다. 따라서 온라인 쇼핑몰 데이터의 장바구니 분석에 전통적 데이터마이닝 기법을 그대로 적용할 경우, Null Transaction의 수가 지나치게 많음으로 인해 합리적 수준의 지지도(Support)를 만족시키는 규칙을 찾는 것이 매우 어렵게 된다. 이러한 이유로 온라인 데이터를 사용한 많은 연구는 동시성 기준을 여러 방법으로 확장하여 사용하였는데, 이들 동시성 기준은 명확한 근거나 합의 없이 연구자의 상황에 따라 임의로 선택된 측면이 있다. 따라서 본 연구에서는 온라인 마켓 분석에 적용되는 구매의 동시성 기준을 정확도 측면에서 평가함으로써, 구매의 동시성 기준 선정을 위한 근거를 제시하고자 한다. 또한 동시성 기준의 정확도가 고객의 평균 구매간격에 따라 상이하게 나타나는 것을 파악하여, 향후 고객의 특성에 따른 차별화된 추천 시스템 구축을 위한 기본 방향을 제시하고자 한다. 이를 위해 국내 대형 인터넷 쇼핑몰의 최근 2년간 실제 거래 내역을 대상으로 실험을 수행하였으며, 실험 결과 단골 고객의 구매 추천을 위한 분석의 경우 추천 범위와 분석 데이터의 동시성 기준을 맞추어 연관규칙을 도출하는 것이 바람직하며, 비단골 고객의 경우 대부분의 추천 범위에 대해서 분석 데이터의 동시성 기준을 비교적 길게 설정하여 연관규칙을 도출하는 것이 바람직한 것으로 나타났다.