• Proceedings of the Korean Society of Computer Information Conference
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• 2013.01a
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• pp.119-121
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• 2013

최초의 컴퓨터 바이러스인 브레인 바이러스가 만들어진 이후로, 현재까지 컴퓨터 바이러스로 인한 피해는 늘어나고 있다. 이에 따라 컴퓨터 바이러스를 막기 위한 여러 가지 노력이 현재도 진행 중에 있다. 컴퓨터 바이러스로 인한 피해 방지와 예방을 위한 대책을 수립하기 위해서는 컴퓨터 바이러스의 발생 빈도수를 예측 하는 것이 필요하다. 본 논문은 다양한 예측 연구에 활용되고 있는 마코프 체인을 적용하였다. 본 논문은 마코프 체인을 적용하여 컴퓨터 바이러스 빈도수를 예측하는 모델링을 제안한다.

• Journal of Welding and Joining
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• v.1 no.1
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• pp.6-12
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• 1983

탄산가스 아아크 용접법은 다른 용접법에 비해 전자세 용접의 기능, 용접능률의 우수성, 생산적인 측면에서의 뛰어난 경제성으로 인해 중공업 분야에서 그 적용 추세가 증가일로에 있다. 당사( 현대중공업)에서는 1981년에 탄산가스 아아크 용접법이 현장 구조물 시공에 최초로 적용된 이래 꾸준히 증가하여 보편적으로 시용되는 용접법 중위 하나가 되었다. 탄산가스 아아크 용접법의 여러 가지 장점을 적극적으로 이용하기 위해서는 탄산가스 아아크 용접시 발생하는 결함의 원 인을 분석하여 결함을 최소화하는 대책이 강구되어야 한다. 탄산가스 아아크 용접시 발생하는 결함의 빈도를 조사하여, 빈도수가 많은 결함의 원인을 분석하고 그 방지대책을 세우는데 본고의 목적이 있다.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2022.10a
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• pp.255-256
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• 2022

본 연구에서는 중대재해처벌법 안전보건관리체계 7가지 핵심요소가 기업의 안전성과에 미치는 영향을 알아보는 최초 연구이다. 이를 위해 중대재해처벌법 안전보건관리체게 7가지 핵심요인별 측정도구를 개발하고 기존 선행연구를 바탕으로 한 안전성과 측정도구를 적용하여 그 관계성과 재해발생빈도 감소의 영향도 확인 한다. 연구결과는 중대재해처벌법 안전보건관리체계 구축이 안전성과에 유의한 결과를 가질 것으로 보이며, 안전보건관리체계 구축이 재해발생빈도 감소에도 직접적인 영향이 미칠 것으로 판단된다. 개발된 중대재해처벌법 안전보건관리체계 구축 측정 도구는 향후 여러 산업분야의 안전관리 및 성과 측정에 많이 활용 되리자 본다. 그리고 향후 안전보건관리체계 구축-안전성과-재해경감활동관리체계 관계연구의 기초 연구가 될 것 이다.

• Fire Science and Engineering
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• v.28 no.2
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• pp.82-90
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• 2014

According to recent government's 3.0 operating paradigm for the opening and sharing of public information, relationship between humidity, temperature and fire occurrence were analyzed using the data in National Weather Service and National Emergency Management Agency. In order to analyze the relationships between humidity, temperature and fire occurrence, hourly frequency of fire occurrence compared with humidity and temperature ranges was suggested as an analysis method. Tendencies of fire occurrence frequencies were examined through this and characteristics of detailed attributes could be statistically identified. Results about hourly frequencies of fire occurrence by classifying the humidity ranges in each region showed increasing frequencies in all areas where the humidity is lower. Hourly frequencies of fire occurrence according to temperature ranges were identified to be similar in each area as well. In addition, characteristics of objects' attributes were analyzed including types of fire, igniting source of fire, initial complex, reasons of fire occurrence, and distinctive directions were suggested. Suggested method in this paper could be practically used when suggesting the frequency in each category in fire occurrence statistics of National Fire Information System.

• Journal of Plant Biology
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• v.28 no.1
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• pp.29-44
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• 1985

This study was carried out to investigate the types and frequency of abnormal stomata in Crassulaceae. We observed the surface of the leaves on twenty four species involved five varieties belonging to eight genera of Crassulaceae. Nineteen types of abnormal stomata were found in the families. Among them three types such as the single guard cell, the aborted stomata, and the single-aborted guard cell were highly observed from nineteen to twenty four species, and two types of the overlapped-thickening guard cells and the arrested stomata exhibited commonly from seven to thirteen species. The another types of them rarely occurred from one to five species. Most of abnormal stomata were found in S. alboroseum, P. chinense and S. sarmentosum, and a few types of them were observed in the other species. The three types of the ballooning guard cells, the cross cleaved stomata, and the fused pore stomata were first reported here in the seed plants. It was thought that the abnormal stomata were formed by the result of degeneration and abnormal development of normal stomata.

• Journal of Chest Surgery
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• v.37 no.2
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• pp.197-200
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• 2004

Although the formation of fistula between esophagus and adjacent organ is a known complication of the self-expanding esophageal stent, only a few cases of surgically treated bronchoesophageal fistula have been reported. Increasing application of endoscopic stent for benign esophageal strictures increases the chance for this type of delayed complication. We experienced a case of bronchoesophageal fistula caused by esophageal stent for which we performed fistulectomy and Ivor Lewis operation simultaneously. To the best of our knowledge, this is the first report on the successful surgical treatment of this complication in Korea.

• Clinical and Experimental Pediatrics
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• v.51 no.8
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• pp.848-855
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• 2008

Purpose : The objective of this study was to ascertain the incidence of congenital heart disease in the western part of Gyeongnam Province in Korea. Methods : We enrolled 849 children (M:F=390:459) who were diagnosed with congenital heart disease (CHD) and received echocardiography during January 1997 to December 2005 in Gyeongsang National University Hospital. The subjects were limited to patients born from 1997 to 2004. The CHDs were classified into acyanotic types and cyanotic type. Further, acyanotic type CHDs were divided into shunt type and valvular types. Results : Numbers of initially diagnosed patients from 1997 to 2004 were as follows: 113, 128, 116, 104, 129, 97, 84, and 78. The median age of initially diagnosed CHD patients was 1 month in the acyanotic type and 0.5 months in cyanotic type. Also, an annual frequency among CHD types and gender ratio were no significant difference in every year. Incidences of CHD from 2000 to 2004 in the western part of Gyeongnam Province were 8.9, 12.7, 10.9, 10.0, and 9.7 per 1,000 live births, respectively. Conclusion : From 1997 to 2001, 100-130, and from 2002 to 2004, less than 100 patients were diagnosed with CHD. This showed a decrease in the numbers of CHD patients in the last three years. However, the Incidence of CHD was 0.89-1.24% during the last five years. Therefore, the decrease in the annual frequency of CHD was due to the recent decline in birth rate in Korea.

• Journal of Digital Convergence
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• v.18 no.9
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• pp.181-190
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• 2020

The purpose of this study is to analyze the trends of wearable keywords using text mining methodology. To this end, 11,952 newspaper articles were collected from 1992 to 2019, and frequency analysis and bi-gram analysis were applied. The frequency analysis showed that Samsung Electronics, LG Electronics, and Apple were extracted as the highest frequency words, and smart watches and smart bands continued to emerge as higher frequency in terms of devices. As a result of the analysis of the bi-gram, it was confirmed that the sequence of two adjacent words such as world-first and world-largest appeared continuously, and related new bi-gram words were derived whenever issues or events occurred. This trend of wearable keywords will be useful for understanding the wearable trend and future direction.

• Journal of Oral Medicine and Pain
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• v.26 no.4
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• pp.395-406
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• 2001

지난 수십년동안, 다양한 레이저기기를 이용하여 치아 경조직에 대한 응용 실험을 수행되었다. 그러나, 발생한 주요한 문제는 열발생과 플라즈마 형성과 같은 부작용이 지속된다는 점이었다. 실망스러운 실험결과에 따라 치아 삭제에 대한 레이저의 응용에 대한 연구가 거의 진행되지 못하였다. 본 연구의 목적은 국내에서 처음으로 개발된 얼비움레이저기기를 사용하여 다양한 에너지 수준과 다양한 펄스빈도에서 법랑질의 삭제율을 비교하고자 하였다. 본 연구에 사용된 레이저기기는 국내에서 최초로 개발된 $2.94{\mu}m$ 펄스를 $250{\mu}s$ 방출하는 얼비움야그레이저 기기이다. 기기의 에너지는 20 mJ에서 350 mJ까지 다양하게 방출하며, 최대 출력은 3.5 W이다. 22개의 치아를 에폭시 레진에 포매하고 경화하였다. 치아의 법랑질을 회전 다이아몬드 칼을 흐르는 물과 함께 사용하여 협측 또는 설측으로 평탄하게 삭제하였다. 제작된 법랑질표면은 6개의 구획으로 구분하여 에너지 수준과 펄스빈도에 따라 조사하였다. 본 연구에서 사용된 표본 수는 132개이며, 삭제율을 조사하기 위한 모든 표본은 22개의 실험 군으로 분류하였다. 실험결과는 다음과 같다. 1. 에너지 수준간에는 유의한 삭제율의 차이가 있었다. 2. 40 및 80 mJ로 조사한 경우에는 펄스빈도 간에 차이가 없었지만, 120 mJ의 출력으로 동일한 에너지를 조사한 경우에는 20 Hz가 40 또는 80 mJ로 조사한 경우 보다 가장 삭제효과가 높았다. 3. 연속조사 한 경우 조사시간 경과에 따라 법랑질의 삭제율은 증가되지 않았다. 결론적으로 효과적으로 법랑질을 삭제하기 위해서는 적절한 에너지와 펄스의 레이저를 사용해야 하며, 또한 항상 정확한 초점거리를 유지해야 할 것으로 사료된다.

• Journal of the korean academy of Pediatric Dentistry
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• v.49 no.3
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• pp.253-263
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• 2022

A buccal pit is a prominent point-like depression that appears at the cervical end of the mandibular molar developmental grooves. A defective buccal pit can be defined as a buccal pit in which the continuity of the dentinoenamel junction is broken and the pit extends to the dentinal level. This study aimed to determine the frequency of buccal pits and defective buccal pits in un-erupted mandibular first and second molars using cone-beam computed tomography (CBCT). The analysis was performed on CBCT images taken from 417 Korean children and adolescents who visited the Department of Pediatric Dentistry, Yonsei University Dental Hospital between 2004 and 2020. Based on cross-sectional views of CBCT images, buccal pits were categorized into 4 classes according to the depth of the pits. The expression rate of the buccal pits was 29.1%. The prevalence of defective buccal pits was 7.9%. The buccal pits tended to develop bilaterally. To date, this is the most comprehensive study on the frequency of buccal pits with the largest sample size. This was the first attempt worldwide to analyze the depth of the buccal pit using CBCT images and to define a defective buccal pit worldwide.