• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2013.06a
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• pp.158-159
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• 2013

포물선 형태의 정상진로를 취하는 태풍은 전향을 한다. 통상 전향할 때, 태풍의 이동속도는 일생 중에서 가장 느리고 세력은 가장 강하다. 이 연구에서는 20년간(1992-2011년)의 데이터를 이용하여 태풍의 전향에 대하여 분석하였다. 얻어진 결과는 다음과 같다. 전향하는 태풍은 특히 8-9월에 많고, 7-10월의 전향 태풍은 전체 전향 태풍의 71%를 차지한다. 이는 7-10월에 발생하는 태풍이 전체 태풍 발생수의 72%를 차지한다는 결과 값과 매우 비슷하다. 20년 동안에 발생한 태풍의 수는 총 484개이며, 그 중 전향한 태풍의 수는 200개로 전체 태풍의 41%를 차지한다. 북태평양에서 전향한 태풍의 수명은 5일과 7일이 가장 많았고, 그 다음은 8일이었다. 전향한 태풍의 평균 수명은 6.8일이었다. 이는 1951년 이후 현재까지 발생한 모든 태풍의 평균 수명인 6.3일보다 다소 긴 값으로, 전향하는 태풍의 수명이 상대적으로 길다는 것을 의미한다. 전향하는 태풍의 약 1/3은 태풍 승격 후 2-3일째에 전향하고, 약 2/3는 1-5일째에 전향한다. 평균 전향일은 태풍 승격 후 4.1일이다. 북위 20-29도에서 전향하는 태풍이 전체 전향 태풍의 52%를 차지하고, 전체 전향 태풍의 69%는 동경 120-139도에서 전향한다. 북위 30-34도에서 전향하는 태풍도 적지 않다. 전향하는 태풍의 평균 전향 위도는 북위 24.6도이고, 평균 전향 경도는 동경 135.1도이다.

• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.2
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• pp.140-146
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• 2015

This paper analyzed recurvature of typhoons by using 20 years meteorological data from 1992 to 2011. The results of this study are as follows. Yearly numbers of typhoon recurvature showed decreasing tendency gradually with decrease of numbers of typhoon occurrence. Typhoons recurvature were especially many between August and October and number of typhoon recurvature between July and October was occupied counts for 71 % of the whole typhoon recurvature. Life of typhoon recurvature in the North Pacific was most frequent at 5 days and 7 days. Mean life of typhoon recurvature was 6.8 days and this numerical value was longer than mean life of the whole typhoon including recuevatute and non-recurvature. Most of typhoons recurvature changed their direction north-eastwards in 20-34 degrees north latitude and 120-139 degrees east longitude. Mean latitude recurvature and longitude recurvature were 25 degrees north latitude and 135 degrees east longitude, respectively.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 1997.03a
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• pp.183-193
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• 1997

추론엔진과 지식베이스를 기반으로 하는 전문가 시스템은 사용목적에 맞게 구성되며,인간의 사고 방식을 모방한 컴퓨터가 올바른 해를 도출시키도록 하는데 궁극적인 목표가 있다. 즉, 추론의 효율성이 전문가 시스템의 효율성을 좌우한다. 시스템이 어떠한 목적을 갖는가에 따라서, 추론 방법과 지식표현 방법등이 결정된다. 최근 추론의 효율성을 극대화하기 위해 이용되고 있는 지식표현 및 추론 방법으로는 Rete, TREAT 등의 트리 표현을 사용하는 전향추론, 관계리스트를 사용하는 직접추론 등이 있다. 전문가 시스템의 성능은 추론을 얼마나 효율적이고 정확하게 하는지에 따라 좌우된다. 본 논문에서는 이러한 추론의 효율성이 지식베이스의 구축형태와 밀접한 관련을 이용하여 효율적인 추론 엔진을 구성하였다. 지식의 표준화가 모듈화가 쉬운 생성규칙을 사용하여 지식을 표현하였으며 , 사용자의 요구에 의해 전향추론, 후향추론이 수행되도록 하였다. 본 논문에서는 추론을 효율적으로 하기위한 기본 방법중, 지식표현을 보다 더 효과적으로 구축하는 방법을 택하였다. 기존의 지식표현방법을 살펴보고, 이를 기반으로 새로운 지시표현 방법인 ECBM(extedned clause bit matrix)과 ERCBM(extended clause bit matrix)을 제안하고 이를 이용하여 전향추론, 후향추혼이 가능한 추론엔진을 구축하였으며 이 두 지식표현을 이용하여 구축되어진 추론엔진을 비교하였다. 이 추론엔진은 기존에 시스템과는 달리 전향, 후향이 모두 효율적으로 수행되어지며, 모든 지식에 대해 적용이 가능한 강력한 범용성을 갖고 있다.

• Journal of the Korean earth science society
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• v.32 no.1
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• pp.73-83
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• 2011

A new method was developed to better understand the principle of Coriolis force. We also investigated the understanding of 5 10th grade students and analyzed their responses. Since no clear explanation about the nature of a rotating disk is provided in school textbooks, it tends to be misunderstood as the earth surface revolving on its axis pointing to the North Pole. This study was carried out focusing on the fact that a rotating disk is the tangential plane at arbitrary latitude. Results showed that there are changes in students' conceptions on the principle of Coriolis force with a new understanding of the rotating disk. In conclusion, a new method used in this study helped students better understand the link between Coriolis force and rotating disk. The method would be helpful to clarify the principle of Coriolis force in school science.

• Journal of the Korean earth science society
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• v.35 no.3
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• pp.168-179
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• 2014

The purpose of this study focuses on the prediction time and location of turning-point of typhoon tracks using the water vapor images of Communication, Ocean and Meteorological Satellite (COMS) which has a very short observation interval. It targets a more accurate prediction of turning-point of typhoon tracks through the relationship between dry slot and northern/southern oscillations of jet stream. Jet stream moves by the position of jet streak and the ${\upsilon}$-component velocity of geostrophic wind. If the ${\upsilon}$-component of geostrophic wind gets stronger toward south, jet stream develops into a circular jet. In that condition, dry slot in satellite water vapor imagery extends toward south, and typhoon track turns as the distance of curved moisture band (CMB) gets narrowed down. If the interval of CMB is below $15^{\circ}$ of latitude, the typhoon track is turning toward north or northeast within 24 hours. As a result, typhoon track showed that when dry slot position was located less than $32^{\circ}N$, typhoon turned its track at $20-23^{\circ}N$ ($1^{th}$ Kong-Rey 2007 and $17^{th}$ Jelawt at 2012), and when in $35^{\circ}N$ above, it turned at $27^{\circ}N$ ($4^{th}$ Man-yi 2007).

• Journal of The Korean Association For Science Education
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• v.36 no.3
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• pp.423-434
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• 2016

The purpose of this study is to investigate preservice earth science teachers' mental models through applications of Coriolis force experiment apparatus. After the root of preconception was examined by face to face interviews based on the questionnaire, five preservice earth science teachers were finally selected for this study. The mental models about concept of Coriolis force was classified into naive mental model, static unstable mental model, dynamic unstable mental model, and scientific mental model through the result of individual interviews and their drawings. According to the mental model analysis about Coriolis' force conception, students C and M showed naive mental model about concept of Coriolis force before experiment. After the experiment, student M's model changed to static unstable mental model. Student C's model improved to dynamic unstable mental model. In adiition, students D and O's model improved from static unstable mental model to dynamic unstable mental model. In the case of student B, the dynamic unstable mental model was maintained after the experiment, however, student B's preconception changed to scientific concept. It turned out that a change occurred from low mental model level to integrated mental model after the application of the developed Coriolis' force experiment apparatus. According to the results, national curriculum is similar to static unstable mental model and the result of developed Coriolis' force experiment apparatus is similar to dynamic unstable mental model. It is suggested that it become the theoretical foundation to develop more comfortable and advanced Coriolis force experiment apparatus by improving the experiment apparatus.

• Journal of the Korean earth science society
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• v.30 no.6
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• pp.787-798
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• 2009

A new apparatus was presented in order to help understand the concept of the Coriolis force which is essential in understanding the trajectories of the atmospheric current and the tide of seawater. In the apparatus proposed in high-school textbooks, since the slide from which the ball is released is set outside the rotating disk, it was not possible to interpret, with the trajectory of the ball on the disk, the motion of the atmosphere and the current of seawater occurring as a result of the Coriolis force. In order to resolve such problem, a new apparatus was developed in which the slide was set on the disk and rotated with the disk. Experiments were carried out using both the existing apparatus and the new apparatus, and the results were compared. While, in the experiment performed with the existing apparatus, it was difficult to analyze the trajectory of ball because the motion of the ball was not smooth when it hit the disk, in the experiment with the new apparatus it was much easier to analyze the trajectories. It was also possible to compare the trajectories when the initial velocity of the ball was varied.

• Journal of the Korean earth science society
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• v.33 no.6
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• pp.544-553
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• 2012

A simple experimental method was developed to help students understand the effect of the Coriolis force on typhoon genesis and movement. It consists of rotating tanks with and without a sloping bottom, and a small stirrer to produce cyclonic typhoon-like vortices by locally stirring the water. Vortices were able to last for more than 3 minutes without dissipation in the rotating tank. However, vortices were hardly maintained without rotation, and would rather disappear as soon as the stirrer stopped mixing. Since the dynamical properties of the rotating water are similar to those of the atmosphere influenced by the Coriolis force, the experiments show that the Coriolis force is indispensable to the typhoon genesis. When the tank had both the sloping bottom and rotation, vortices would move in a particular direction. Considering the topographical beta effect, this result indicates that typhoons are drifted not only by the steering wind but also by the meridional gradient of the Coriolis force. The methodology developed in this study, would be useful for both students and teachers to better the relationship between the Coriolis force and the typhoon genesis.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.7 no.2
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• pp.170-178
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• 2004

Purpose: Helicobacter pylori (H. pylori) infection has been known to be vital in the pathogenesis of duodenal ulcer disease in children as well as in adults. But the relationship between H. pylori infection and the histopathologic findings of the duodenum has not been explained obviously in children yet. So the aim of this study is to determine whether duodenitis and/or gastric metaplasia in the duodenum increases the risk of duodenal ulcer disease in children infected by H. pylori. Methods: From October 2001 to April 2004 gastric and duodenal biopsies were performed in 177 children who visited Department of Pediatrics, Gil Hospital, Gachon Medical School. Biopsy sections were stained with hematoxylin and eosin and also with Giemsa for identification of H. pylori. The grades of duodenitis and gastric metaplasia were classified from 0 to 3 and from 0 to 4, respectively. Results: The incidence of H. pylori infection was 54% in total patients. Amongst 163 children with duodenitis there was a lack of correlation between H. pylori infection and the grade of duodenitis. Amongst 11 patients with duodenal ucler, only 4 children were infected by H. pylori. And amongst 5 patients with gastric metaplasia, H. pylori and duodenal ulcer were detected in 2 and 3 children, respectively. The occurrence of duodenal ulcer and gastric metaplasia were increased significantly in proportion to the grade of duodenitis (p<0.0001 and p=0.0365, respectively). Conclusion: As opposed to the results of previously reported articles, there were lacks of correlation between H. pylori infection and duodenitis, duodenal ulcer, and gastric metaplasia. So further study hould be done to clarify the effect of H. pylori on the duodenal histopathology in children infected by H. pylori.

• The Journal of the Convergence on Culture Technology
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• v.6 no.1
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• pp.449-454
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• 2020

We propose an improved de-interlacing method that converts the interlaced images into the progressive images by one field. In the first, Inter-pixel values are calculated by applying Newton's forward difference, backward difference interpolation from upper and lower 5 pixel values. Using inter-pixel values obtained from upper and lower 5 pixel values, it makes more accurate a direction estimate by applying the correlation between upper and lower pixel. If an edge direction is determined from the correlation, a missing pixel value is calculated into the average of upper and lower pixel obtained from predicted direction of edge. From simulation results, it is shown that the proposed method improves subjective image quality at edge region and objective image quality at 0.2~0.3dB as quantitative calculation result of PSNR, compared to previous various de-interlacing methods.