• Title/Summary/Keyword: 안창현

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Simple bone cysts of two brothers (형제에서 발견된 단순골낭)

  • An, Seo-Young;An, Chang-Hyeon;Choi, Karp-Shik
    • Imaging Science in Dentistry
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    • v.38 no.3
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    • pp.183-187
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    • 2008
  • 17-year-old and 14-year-old brothers were referred for evaluation of the cystic lesions on the mandibular anterior area with no symptoms. Neither their mother nor the brothers could recall any past trauma to those areas. Panoramic and intraoral radiographs revealed moderately defined cystic lesions on their mandibular anterior areas. Biopsies on both lesions revealed simple bone cysts. Hereditary cause or familial history of simple bone cysts could not be found in literature review. This case may have been a coincidence. However, further investigation is needed to find the cause of simple bone cysts occurring in patients those are closely related.

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Radiographic study of the unicystic ameloblastoma (단방성 법랑모세포종의 방사선학적 연구)

  • Lee Ju-Duck;An Chang-Hyeon;Choi Karp-Shik
    • Imaging Science in Dentistry
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    • v.35 no.1
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    • pp.47-50
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    • 2005
  • Purpose : To acquire the useful diagnostic information through the analysis of the clinical and radiological characteristics of mandibular unicystic ameloblastoma. Materials and Methods : The researchers compared and analysed the clinical and radiological features of 79 cases of mandibular unicystic ameloblastoma confirmed by histopathlogic examination. Results : The results of our research showed that unicystic ameloblastomas occurred more frequently in males than in females and the incidence is the highest in the 2nd and 3rd decades. These lesions occurred most frequently in angle-ramus area, mandibular molar area, and anterior area in descending order respectively $68.4\%$, $24\%$, and $7.6\%$. These lesions had smooth ($54.4\%$) rather than undulating ($45.6\%$) borders. These lesions showed well- defined borders in $59.5\%$ among all the cases. Root resorption and loss of lamina dura were observed as $55.7\%$ and $58.5\%$ respectively. Displacement of mandibular canal was observed in $55.9\%$ among all the related cases. Internal pattern of lesional radiolucency was observed as even ($49.4\%$) or uneven ($50.6\%$). Conclusion : These results would be helpful in diagnosing of mandibular unicystic ameloblastoma. (Korean J Oral Maxillofac Radiol 2005; 35 : 47-50)

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How to Choose and Use the CBCT (임상가를 위한 특집 1 - CBCT의 선택과 처방)

  • An, Chang-Hyeon
    • The Journal of the Korean dental association
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    • v.52 no.3
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    • pp.132-138
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    • 2014
  • The emergence of Cone Beam Computed Tomography(CBCT) in the late 1990s represented an innovative advancement in the field of dental and maxillofacial radiology because it greatly reduced the radiation exposure to patients and offered 3D images easily. The 3D information generated by this technique brings the potential of improved diagnosis and treatment planning for a wide range of clinical applications in dentistry. The use of CBCT includes diagnosis and surgical assessment of the orofacial hard tissue lesions, dental implant treatment planning and postoperative evaluation, TMJ assessment, diagnosis of craniofacial fracture, orthodontics, endodontics, and so on. All CBCT examinations should be justified on an individualized needs. The clinical benefits to the patient for each CBCT scan must outweigh the potential risks associated with exposure to ionizing radiation. CBCT scans should be taken with initially obtained medical and dental histories of patients and a close clinical examination. CBCT should be considered as an imaging alternative of other conventional radiography in cases where the anatomical structures of interest may not be seen. The smallest possible field of view(FOV) and the lowest setting of tube current and scan time should be chosen, and the entire images scanned should be interpreted by a qualified expert.

A case report of an inverted papilloma infiltrating into maxillary sinus (상악동을 침범하는 역위성 유두종의 증례보고)

  • Ji, Yong-Hwa;Choi, Bo-Ram;Huh, Kyung-Hoe;An, Chang-Hyeon;Lee, Sam-Sun
    • Imaging Science in Dentistry
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    • v.39 no.2
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    • pp.103-107
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    • 2009
  • The present study reports a case of inverted papilloma of the nasal cavity and infiltrating into the maxillary sinus. Inverted papilloma is an uncommon and locally aggressive benign tumor of the sinonasal region. The patient, 51year-old male, presented with unilateral nasal obstruction and periodic swelling on the palate without pain. Enhanced CT scan revealed a heterogeneously enhancing solid mass in the nasal cavity and infiltrating into the right maxillary sinus, as well as an incidental, secondarily infected residual cyst in the periapical area of the right maxillary canine. The sinonasal mass was revealed as an inverted papilloma on histopathologic examination. (Korean J Oral Maxillofac Radiol2009; 39: 103-7)

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Development of Evaluation Technique of Mobility and Navigation Performance for Personal Robots (퍼스널 로봇을 위한 운동과 이동 성능평가 기술의 개발)

  • Ahn Chang-hyun;Kim Jin-Oh;Yi Keon Young;Lee Ho Gil;Kim Kyu-ro
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.52 no.2
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    • pp.85-92
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    • 2003
  • In this paper, we propose a method to evaluate performances of mobile personal robots. A set of performance measures is proposed and the corresponding evaluation methods are developed. Different from industrial manipulators, personal robots need to be evaluated with its mobility, navigation, task and intelligent performance in environments where human beings exist. The proposed performance measures are composed of measures for mobility including vibration, repeatability, path accuracy and so on, as well as measures for navigation performance including wall following, overcoming doorsill, obstacle avoidance and localization. But task and intelligent behavior performances such as cleaning capability and high-level decision-making are not considered in this paper. To measure the proposed performances through a series of tests, we designed a test environment and developed measurement systems including a 3D Laser tracking system, a vision monitoring system and a vibration measurement system. We measured the proposed performances with a mobile robot to show the result as an example. The developed systems, which are installed at Korea Agency for Technology and Standards, are going to be used for many robot companies in Korea.

Wave overtopping at concave corner for vertical wall (직립제 우각부에서의 월파량)

  • Ahn, Chang-Hyun;Kim, Young-Taek
    • Proceedings of the Korea Water Resources Association Conference
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    • 2012.05a
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    • pp.727-727
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    • 2012
  • 최근 제체 설치수심의 대수심화로 인해 직립 케이슨제의 건설이 주를 이루고 있으며, 외곽시설의 경우 평면배치에 의하여 곡면부 구간이 형성된다. 이와 같은 구간에서는 파랑 증폭이 발생할 수 있다. 특히 우각부 구간에서의 파랑증폭에 의한 월파량 산정은 기존 직각으로 입사하는 조건에 대한 월파량 산정 방법과는 다른 해석이 필요하다. 본 연구에서는 직립제 우각부에 대한 월파량 분포를 검토 및 분석하고자 한다. 그림 1과 같이 우각부의 각도를 $10^{\circ}{\sim}30^{\circ}$로 제작했으며, 각각 발생시킨 파랑의 주기는 1.18초, 1.38초, 1.57초, 1.77초, 1.98초, 파고는 7.5cm, 10cm, 12.5cm이다. 또한 그림 2와 같이 각 월파가 일어나는 직립제 모형의 여유고를 7.5cm, 10cm, 12.5cm, 15cm를 적용하였다. 우각부 구간에서 월파의 공간적인 분포를 수리모형 실험을 통하여 검토하였다. 월파의 공간적인 분포를 검토하기 위하여 월파량 영향계수( )를 도입하였다. 우각부가 없는 직각으로 입사하는 조건의 월파량 실험을 통해 그 월파량의 값이 영향계수의 $r_x=1.0$이며, 우각부 중심을 기준으로 구조물을 따라서 공간적인 월파량 영향계수를 산정하였다.

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Leavening Ability of the Isolate Saccharomyces cerevisiae MF10003 in Bakery Dough (분리 효모 Saccharomyces cerevisiae MF10003의 빵반죽 발효 팽창력)

  • Oh, Jung-Suk;Min, Eung-Ki;Ahn, Chang-Hyun;Han, Yeong-Hwan
    • Journal of Life Science
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    • v.23 no.2
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    • pp.222-227
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    • 2013
  • An effective leavening yeast was isolated from raisin broth. The isolate was identified as Saccharomyces cerevisiae by comparing the homology of 18S rDNA ITS sequences and named as S. cerevisiae MF10003. S. cerevisiae MF10003 showed a 1.9-fold and 3.1-fold increase in $CO_2$ production and leavening ability, respectively, compared with the wild yeast S. ellipsoideus KCTC7243, and the dough had a rich and volatile flavor. When glucose, sucrose, fructose, and maltose were added to the culture broth as a carbon and energy source, $CO_2$ was produced in 4 hr.

Peripheral Osteoma of the Mandible (하악골에 발생한 변연성골증)

  • An Chang-Hyeon;Heo Min-Suk;Lee Sam-Sun;Choi Soon-Chul;Park Tae-Won
    • Journal of Korean Academy of Oral and Maxillofacial Radiology
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    • v.29 no.2
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    • pp.523-531
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    • 1999
  • Purpose: To determine the clinical and radiological features of peripheral osteoma of the mandible (POM) in a Korean population and to compare with previous reports. Materials and Methods: Sixteen cases of POM found in 15 Korean patients who visited Seoul National University Dental Hospital between 1980 and 1998 were reviewed to determine their clinical and radiological features. Results: The 15 patients. five males and ten females. ranged in age from 22 to 69 years. with a mean age of 40.7 years. Six POMs were located on the buccal side of the mandibular body and five on the lingual aspect of the mandibular body and five on the lower border of the mandible. The duration of the lesion ranged between 1 and 10 years. The size of the lesions. in their great diameter. ranged from 6 to 26 mm. with a mean of 14.1 mm. Six POMs were pedunculated. nine sessile. and one bell-shaped. Eleven POMs were compact types and five were cancellous ones. Conclusion: The clinical and radiological features of these Korean series were broadly consistent with those of non-Korean populations reported previously. The principal difference was that all POMs under 35 year-old age were compact types.

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Metastatic thyroid follicular carcinoma of masticator space (저작근극에서 발생한 전이된 갑상선 여포상암)

  • Gang Tae-In;Heo Min-Suk;An Chang-Hyeon;Choi Mi;Lee Sam-Sun;Choi Soon-Chul;Park Tae-Won
    • Imaging Science in Dentistry
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    • v.32 no.3
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    • pp.175-179
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    • 2002
  • Follicular carcinomas are the second most common form of thyroid cancer, accounting for 10 to 20% of all thyroid cancers. Follicular carcinomas have a propensity to metastasize via the bloodstream, spreading to bone, lungs, liver, and elsewhere. We described the case of a 48-year-old woman who presented with swelling of the left preauricular area, which was a consequence of a metastatic follicular carcinoma of the masticator space. Plain films showed illdefined erosive bony changes from the left condylar head to the mandibular notch. Contrast-enhanced CT images showed a well circumscribed round mass with well enhancement within left masticator space. On MR images, the mass was heterogenously hyperintense to the muscle on T2-weighted images and isointense or hyperintense to the muscle on Tl-weighted images, and showed good enhancement on contrast-enhanced Tl-weighted images. Upon microscopic examination, the metastatic mass was found to be composed of fairly uniform cells forming small follicles containing colloid, showing capsular and vascular invasion.

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Public Service Broadcasting and Accountability: Case Study on NHK (공영방송의 '설명책임'에 관한 연구: NHK의 '개혁재생사업'을 중심으로)

  • Ahn, Chang-Hyun
    • Korean journal of communication and information
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    • v.41
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    • pp.268-302
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    • 2008
  • This paper analyzes an NHK's 'Performances of Reform and Revival'. As a result of analysis, it was focused on reinforcement of the management such as audit, corporate governance, compliance, and thus the accountability was insufficient. Generally speaking, public service broadcasting is the form of organization of mass media that is most directly accountable to society. Therefore, the efforts is required for public service broadcasting to figure out to endow the social roles and responsibilities to themselves differentiated from other commercial broadcasters. And it is necessary that the concrete systems and activities based on an answerability model so that public broadcasters fulfill the accountability. Answerability means that broadcasting organizations and journalists both take account of and are accountable to the public. In such a process, the positive and voluntary civic participation is indispensable.

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