• Geophysics and Geophysical Exploration
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• v.19 no.4
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• pp.236-248
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• 2016

In this review, the basic concepts of geodetic coordinate system and map projection are explained to practitioners in exploration geophysicists to enhance the understanding of geographic and projected coordinate system. The fundamental elements such as earth ellipsoid, geoid, geocentric and geodetic latitudes, rhumb line, and great circle are dealt with in detail. The geocentric and geodetic coordinate systems are also summarized neatly, together with coordinate conversion formulae. In addition, the concept and technique for datum transforms between local and world datum are presented, with special emphasis on Korean Geodetic System.

• Journal of Chest Surgery
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• v.32 no.1
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• pp.49-52
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• 1999

A 58-year-old male patient visited our hospital for epigastric discomfort and dysphagia which had developed 5 months earlier. He was diagnosed with esophageal cancer at the mid-thoracic level based on radiologic, endoscopic, and histologic examinations. An esophagectomy(Ivor Lewis technique) was done to treat the esophageal cancer. He was doing well until the 20th postoperative day when he began to complain of cough, sputum, fever and chills, Subsequently, thereafter, abdominal pain and generalized abdominal tenderness developed on the 22nd postoperative day. Upon gastrofiberscopy and esophagographic examinations, he was diagnosed with gastrobronchial fistula and an emergency operation was performed. On operative findings, the gastric fundus was perforated and directly connected to the abscessed cavity of the right upper lobe due to a gastric ulcer. We, herewith, report this case after review of the literature.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.3 no.2
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• pp.151-159
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• 2000

Purpose: Recently, a wide application of gastrofiberscopy in the pediatric group have revealed that nodular duodenitis is not an uncommon disease in children and is suspected to be associated with H. pylori infection. The aim of this retrospective study was to investigate the clinical and histopathologic features in children with nodular duodenitis, and to assess the correlations beween both. Methods: During a period of 5 years (Jan. 1995~Dec. 1999), we investigated clinical, endoscopic and histopathologic features of 39 consecutive patients diagnosed as having nodular duodenitis at Pediatric department of Seoul Red Cross Hospital. In 35 children with nodular duodenitis endoscopic biopsy specimens were stained with Hematoxylin & Eosin and Giemsa's stain, and were graded according to the criteria outlined by Triadafilopoulos, Whitehead et al., and Prieto et al.. Statistical analyses were performed with Graph PAD InStat. Results: The prevalence rate of nodular duodenitis was 17.1% and the most frequent chief complaint was abdominal pain (69.2%). Endoscopically grade 1 was the most common (45.7%) and nodular gastritis was coexistent in 28.3%. The most common histology of the duodenum was grade 2 (54.3%), and the most common histologic score of the stomach was 2 (42.9%). H. pylori was found in the duodenum in 37.1%, and in the stomach in 31.4%. The correlation coefficient between the endoscopic grade and the histologic grade of nodular duodenitis was 0.3983 (p=0.0178). And the correlation coefficient between the histologic grade and the grade of H. pylori colonization in the duodenum was 0.5154 (p=0.0018). Conclusion: There was significant correlation between the endoscopic grade and the histologic grade of nodular duodenitis, and was also significant correlation between the histologic grade and the grade of H. pylori colonization in the duodenum. Therfore H. pylori infection should be regarded as an etiologic factor of nodular duodenitis.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.4
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• pp.569-576
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• 2022

In this study, the healing performance of hybrid self-healing concrete was investigated by mixing bacterial pellets(BP) and solid phase capsules(SC), respectively, based on organic-inorganic self-healing material(MC). Constant water head permeability test was applied as a method of evaluating the healing performance, and the healing rate and the healed crack width calculated by the equivalent crack width were used as evaluation indicies. As a result of the water permeability test, when the initial crack width was 0.3 mm, the healing rates of MC-BP and MC-SC were 2.1~3.0 %pt higher than that of MC, and the healed crack width of hybrid concrete increased by 0.017~0.018 mm. In conclusion, it was found that the self-healing performance was not significantly improved even if the two types of healing materials are used together.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.565-569
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• 2007

To find optimal path is killer application in the telematics system. The shortest path of conventional system, however, isn't always optimal path. That is, the path with minimum travelling time could be defined as optimal path in the road networks. There are techniques and algorithms for finding optimal path. Hierarchical path algorithm categorizes road networks into major layer and minor layer so that the performance of operational time increases. The path searched is accurate as much as optimal path. At above 2 system, a method to allocate minor roads to major road region influences the performance extremely. This paper proposes methods to determine search space for selecting major roads in the hierarchical path algorithm. In addition, methods which apply the proposed methods to hierarchical route algorithm is presented.

• Journal of Gastric Cancer
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• v.4 no.2
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• pp.75-81
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• 2004

Recently detection of early gastric cancer (EGC) has been increasing and the treatment strategies for gastric cancer have been changing. The purpose of this study was to compare clinical outcomes between laparoscopically assisted (LADG) and hand-assisted laparoscopic gastrectomy (HALDG) and open distal gastrectomy for early gastric cancer. This review is directed toward providing gastric surgeons with recent advances in the treatment of EGC. We investigated the English language literature for the past 12 years through computer searches which focused on : 1) Patient demographics, 2) Operation time, 3) Intra-operative blood loss, 4) Depth of invasion, 5) CBC, 6)Weight loss, 7) Analgesic requirement, 8)Time NPO, 9) Length of hospital stay, 10) Tumor stage, 11) Lymph node (LN) dissection, 12) Position of LN resected, 13) Complications. Improved operative techniques and surgical instrumentation have facilitated the development of minimally invasive gastric cancer surgery. The short-term benefits of laparoscopic gastrectomy included less surgical trauma, less pain, rapid return of gastrointestinal function, and shorter hospital stay, with no change in operative outcome. Laparoscopic gastrectomy was better accepted by the patients as a good procedure and promptly brought the patients back to their previous lifestyle and activities of daily living. But the advantages of HALDG for gastric cancer, extended lymph node dissection and intracorporeal anastomosis are feasible and easier with the presence of the internal hand. The hand-assisted laparoscopic (HALDG) method reported the best results in lymph node dissection.This method is an alternative to total laparoscopic radical gastrectomy. LADG and HALDG, when compared with conventional open gastrectomy, have several advantages. When performed by a skilled surgeon, LADG and HALDG are safe and useful techniques for patients with early-stage gastric cancer. Their appropriateness for gastric cancer surgery require further study.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.4
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• pp.781-787
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• 2007

Network Mobility (NEMO) basic support protocol doesn't execute the process of route optimization and has not presented the particular security mechanism in other blocks except hi-directional tunnel between Mobile Router (MR) and its Home Agent (HA). Therefore in this paper we process secure route optimization courses through authenticated binding update protocol between MR and its Correspondent Node (CN) and the protocol of the competency of mandate between MR and its Mobile Network Node (MNN); its block also uses an bi-directional tunnel as the block between MR and its HA. The address of each node are generated by the way of Cryptographically Generated Address (CGA) for proving the ownership of address. Finally we analyze the robustness of proposed protocol using security requirements of MIPv6 and existing attacks and the efficiency of this protocol using the connectivity recovery and end-to-end packet transmission delay time.

• Journal of Korean Society of Transportation
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• v.15 no.1
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• pp.175-192
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• 1997

첨단 교통정보 시스템(ATIS)의 핵심요소라고 할 수 있는 동적경로안내 시스템 (Dynamic Route Guidance System)은 운전자가 목적지에 도착하기까지 실시간 교통정보를 토대로 최적경로를 안내해줌으로써 날로 심화되고 있는 교통혼잡을 최소화 할 수 있으리라 기대를 모으고 있다. 특히 교통사고나 긴급 도로공사 등으로 인해 발생하는 돌발적 교통혼잡하에서는 DRGS의 역할이 더욱 커질 것으로 예상되고 있다. 본 논문은 돌발적 교통혼잡하에서 보다 효과적인 DRGS의 경로안내 전략을 수립하고 평가하는데 그 목적이 있다. 이를 위해 우선 하부구조기반 DRGS와 개인차량기반 DRGS의 장단점을 비교하고 시스템 아키텍쳐와 경로안내전략의 관계를 규명하였다. 또한 효율적인 경로안내를 위해 사용자평형 (User Equilibrium) 경로안내전략과 시스템 최적화(System Optimal) 경로안내 전략을 이상형교통망 (Idealized Network)을 통해 비교 분석하였다. 그리고 돌발적 교통 혼잡하에서 사용자평형 경로 안내를 사용할 경우 야기될 수 있는 Braess Paradox 문제와 시스템 최적경로안내를 사용할 경우 일어날 수 있는 사용자 호응도(User Compliance) 문제를 동시에 감안한 적응 형 경로안내 전략을 개발하였다. 이 방법은 위의 경로 안내 전략들이 가지고 있는 장단점을 상황에 따라 평가하여 경로안내 전략을 선택하는 과정을 수행시간을 절약하지 못할 것으로 평가되면 사용자 호응도를 고려하여 사용자 평형 전략을 선택하도록 하였다. 돌발적 교통 혼잡하에서 통행 시간을 동적으로 예측하기 위해서는 이산 확정적 대기행렬모형 (Discrete Deterministic Queueing Model)이 적용되었다. 한편, 적응형 전략의 효율성을 평가하기 위 해 이상형교통망과 실제 미국 Virginia 주의 Fairfax Country에 소재한 주간 고속도로 66번 과 인접 교통망을 대상으로 각종 돌발교통혼잡상황을 전제로 한 Traffic Simulation과 정보 제공 시나리오를 INTEGRATION Model을 사용하여 실행하였다. 그 결과 적응형전략이 단지 사용자평형 경로안내전략만 사용하는 경우에 비해 교통 혼잡도와 유고상황의 체류정도에 따라 3%에서 10%정도까지 전체통행시간을 절약할 수 있다는 결론을 얻었다.

• The Journal of Bigdata
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• v.6 no.2
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• pp.29-38
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• 2021

Deviation of route in aviation safety management is a dangerous factor that can lead to serious accidents. In this study, the anomaly score is calculated by classifying the tracks through clustering and calculating the distance from the cluster center. The study was conducted by extracting tracks within 100 km of the airport from the ADS-B track data received for one year. The wake was vectorized using linear interpolation. Latitude, longitude, and altitude 3D coordinates were used. Through PCA, the dimension was reduced to an axis representing more than 90% of the overall data distribution, and k-means clustering, hierarchical clustering, and PAM techniques were applied. The number of clusters was selected using the silhouette measure, and an abnormality score was calculated by calculating the distance from the cluster center. In this study, we compare the number of clusters for each cluster technique, and evaluate the clustering result through the silhouette measure.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.421-421
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• 2022

만경강 유역은 우리나라의 농업지역 중 하나로 많은 농업용수를 필요로 하는 지역으로 농업용수 공급을 위하여 다수의 취입보가 설치되어 있으며, 충분한 농업용수 확보를 위하여 다른 지역과 달리 가동보와 고정보가 병설로 설치되어 있는 곳이 많다. 통상적인 가동보는 농업용수 확보와 공급을 위하여 농번기인 4월~9월까지 운영되는 것이 일반적이며, 이러한 가동보 운영으로 인하여 다양한 수위-유량관계의 변동성이 발생한다. '20년부터 전주천에 위치한 취입보는 과거와 달리 기존의 월류 높이가 높은 보의 형태에서 어도가 넓고, 보의 높이가 낮은 친환경 월류보의 형태로 전환이 이루어지고 있으며, 그 영향으로 인하여 과거의 수위-유량관계와는 상이한 결과가 발생한다. 하도의 변동성은 단면 측량 등으로 확인 할 수 있으나, 가동보 운영과 공사와 같이 통제특성에 의한 변동사항이 발생하는 경우 모니터링이 필수적이다. 본 연구에서는 만경강 유역에 위치한 전주시(미산교)관측소를 대상관측소로 선정하였으며, 대상관측소는 '20년 12월~'22년 1월까지 친환경 월류보 전환을 위하여 가동보 운영과 공사가 진행된 관측소이다. '20년 12월 친환경 월류보 형태의 전환을 위하여 가동보 운영을 시작하였으며, '21년은 1월~3월은 유지유량을 위한 가동보 운영을 실시하였으며, 4월~9월은 농업용수 확보를 위한 가동보 운영을 실시하였고, 10월~12월은 하도 내 공사 진행에 따라 가동보와 고정보를 같이 운영하였다. 이 기간동안 가동보와 고정보 모니터링을 실시하였으며, 정확한 유량측정성과와 곡선식 확인을 위하여 동일한 위치에서 측정을 수행하였다. 가동보 운영과 공사영향 모니터링 결과와 유량측정성과를 바탕으로 수위-유량관계 변화를 분석하였으며, 저수위 구간은 가동보 운영에 따라 총 11차례 기간분리가 발생하였으며, 중수위 구간도 가동보 운영으로 인하여 과거와 상이한 경향이 발생하여 곡선식을 재개발 하였다. 결과적으로 본 연구에서는 가동보 운영에 따른 다수의 유량측정성과를 확보하였으며, 확보한 유량측정성과의 분석을 통한 신뢰도 높은 수위-유량관계곡선식을 개발하였고 이를 통해 생산된 유량자료는 정확도가 매우 높은 것으로 분석되었다.