• Journal of Chest Surgery
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• 제29권2호
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• pp.136-146
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• 1996

Studies on normal human embryos and on malformed human hearts have been two main sources of the information on the developmental cardiology, Recent advances in the biological technology has opened a new era and descriptive embryology is being shifted into dynamic developmental biology. In this review, we discuss the current understanding on the cardiac embryology relevant to clinical practices of pediatric cardiology. Classical cardiac embryology starts with understanding on five segments of a straight heart tube : the sinus venosus, the primitive atria, the embryonic left ventricle, the embryonic right ventricle and the truncus arteriosus. Key steps in the normal morphogenetic process are the complex spiral septation of ventriculoarterial junction and two jumping connections : between the embryonic right atrium and embryonic right ventricle, and between the embryonic left ventricle and the aorta. Only after these two steps are successfully completed, the third fetal stage tak s place, when myocardial growth and remodeling take place There are two outstanding progresses on the cardiac embryology during recent five-year period. One is immunohistochemical mapping of the conduction system in the developing heart and the other is the understanding on the neural crest cell migration followed by molecular detection of the microdeletion of chromosome 22. A balanced progress of classical morphological studies, modern biological technics and advanced clinical medicine is an urgent task for doctors and scientists dealing with children with sick hearts.

• 대한후두음성언어의학회지
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• 제10권2호
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• pp.119-123
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• 1999

Background and Objectives : Conditions such as muscle atrophy, stretching of strap muscles, and continued craniofacial growth factors have been cited as contributing to the changes observed in the vocal tract structure and function in elderly speakers. The purpose of the present study is to compare F$_1$ and F$_2$ frequency levels in elderly and young adult male and female speakers producing a series of vowels ranging from high-front to low-back placement. Material and Methods : The subjects were two groups of young adults(10 males, 10 females, mean age 21 years old range 19-24 years) and two groups of elderly speakers(10 males, 10 females, mean age 67 years : range 60-84 years). Each subject participated in speech pathologist to be a speaker of unimpared standard Korean. The headphone was positioned 2 cm from the speakers lips. Each speaker sustained the five vowels for 5 s. Formant frequency measures were obtained from an analysis of linear predictive coding in CSL model 4300B(Kay co). Results : Repeated measure AVOVA procedures were completed on the $F_1$ and $F_2$ data for the male and female speakers. $F_2$ formant frequency levels were proven to be significantly lower fir elderly speakers. Conclusions : We presume $F_2$ vocal cavity(from the point of tongue constriction to lip) lengthening in elderly speakers. The research designed to observe dynamic speech production more directly will be needed.

• 조명전기설비학회논문지
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• 제16권2호
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• pp.71-80
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• 2002

영구자석형 선형동기전동기(PMLSM)는 고속, 고추력의 직선추진이 가능하므로 산업현장에서 위치결정장치나 물류반송시스템 및 공작기계 등의 선형 서보 시스템에 이용이 되고 있다. 본 논문에서는 PMLSM의 AC 서보화를 위해 동기 프레임상에서 제어구조가 미리 설정된 스위칭 함수에 따라 불연속적으로 변화되는 가변구조 전류제어방식 및 간접 벡터제어이론을 기본으로하여 도달시간을 제거하고, 구동시스템의 추력 이용도를 높이기 위해 파라미터 변동과 한정된 외란에 거의 영향을 받지 않으며 오버슈트가 없는 고속응답을 실현하기 위해 슬라이딩 모드제어 알고리즘을 제안하여 PMLSM의 위치제어에 적용하고자 한다.

• Journal of Radiation Protection and Research
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• 제43권2호
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• pp.39-49
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• 2018

Background: A model to assess the activity concentration of agricultural products and the public ingestion dose as result of a nuclear accident is necessarily required to manage the contaminated agricultural systems by the accident, or to estimate the effects of chronic exposure due to food ingestion at a Level 3 PSA. Materials and Methods: A dynamic compartment model, which is composed of three sub-modules, namely, an agricultural plant contamination assessment model, an animal product contamination assessment model, and an ingestion dose assessment model has been developed based on Korean farming characteristics such as the growth characteristics of rice and stockbreeding. Results and Discussion: The application study showed that the present model can predict well the characteristics of the activity concentration for agricultural products and ingestion dose depending on the deposition date. Conclusion: The present model is very useful to predict the radioactivity concentration of agricultural foodstuffs and public ingestion dose as consequence of a nuclear accident. Consequently, it is expected to be used effectively as a module for the ingestion dose calculation of the Korean agricultural contamination management system as well as the Level 3 PSA code, which is currently being developed.

• 한국항만경제학회지
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• 제30권2호
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• pp.93-112
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• 2014

한국 해운 물류기업의 경영성과를 연구하기 위해 2012년 매출액이 높은 해운기업 10개, 물류기업10개를 대상으로 2005년부터 2012년까지 재무실적을 기준으로 기업별 성과를 알아보고 사업구조에 따라 4개 유형으로 구분하였다. DEA 활용한 성과측정을 위해 투입요소는 비유동자산과 인건비로, 산출요소는 매출액과 순이익으로 설정하고 CCR, BCC 효율성 분석과 재무실적을 기준으로 성장성과 수익성을 연구하였다. 분석 결과, 효율성과 성장성과수익성을 전체적으로 보면 물류기업의 경영성과가 해운기업보다 높게 나타났고 대기업계열 물류기업의 성과가 물류전문 기업보다 상대적으로 높았다. 정기선 해운기업과 부정기선 해운기업의 최근 성과는 해운시황의 악화 등에 의해 부진한 것으로 나타났다. 세부적으로 보면 대형 화주를 안정적으로 확보하고 장기간 계약구조를 유지하고 있는 기업의 효율성이 높은 것으로 나타났고, 성장성을 보면 다수의 기업에서 비유동자산과 인건비, 매출액이 꾸준하게 증가하고 있는 반면 수익성에서는 대기업계열, 물류전문기업의 수익은 흑자구조를 보이고 있지만, 해운기업의 경우 2008년까지는 물류기업보다 수익성이 높았지만 2009년 이후 많이 악화된 것으로 나타났다.

• 디지털융복합연구
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• 제9권1호
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• pp.177-187
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• 2011

개방, 참여, 공유로 대표되는 웹2.0 인터넷 흐름 속에 새롭게 세간의 화두가 되면서 급성장하고 있는 소셜 미디어, 모바일 미디어 환경 속에서 경제, 사회, 문화는 물론, 정치 분야에도 전반적이고 다양한 변화를 꾀하여야 한다. 한국은 과거의 IT기술력을 바탕으로 새로 다가오고 있는 소셜미디어 환경 속에서도 세계 시장에서 선도적인 역할을 해나가는 위치를 찾아 가고 있다. 우리 국민은 과거 IT 분야에서 새로운 제품에 대한 Early Adopter역할을 해내어 국제 사회에 관심을 끌은바 있다. 급속히 변하해가는 소셜미디어 환경 속에서 정치 분야에서도 이에 맞는 방식으로 친 국민 의사소통 방식이 이루어 질수 있도록 노력해야 한다. 스마트 시민 정당 조직으로서의 비전을 정비하고 소셜미디어 전략을 마련하고 실행하는 등 변화의 노력을 시도하여야 한다. 본 연구에서는 이러한 소셜미디어 환경 속에서 어떠한 방법론으로 변해야 보다 더 친밀하게 국민에게 다가가고 국민과 하나가 되는 성공을 거둘 수 있는가에 대해 연구하고 방향을 제시 해 보고자 한다. 이 연구가 기존 정부 운영이나 정당 운영 방식에 대해 되돌아보게 하고 소셜미디어 환경에 맞는 효율적인 운영 전략을 되새겨 보게 하는 데 일조하게 될 것이다.

• International Journal of Oral Biology
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• 제36권4호
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• pp.195-201
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• 2011

Matrix metalloproteinases (MMPs) have been implicated in tissue development and re-modeling. Dynamic morphological changes of tooth germs reflect involvement of these enzymes during odontogenesis. The present study was performed to investigate expression and localization of MMP-2 and MMP-9, which have been known to have type IV collagenase activities, in rat tooth germs at different developmental stages. MMP-2 expression was increased gradually in the tooth germs from cap to crown staged germs at both transcription and translation levels. The localization of this molecule was detected in secretory ameloblasts and preameloblasts. The strong immunoreactivities were occasionally seen along the basement membrane between ameloblasts (or preameloblasts) and odontoblasts (preodontoblasts). However, weak reactivity was detected in odontoblasts and reduced enamel epithelium. The level of MMP-9 expression in the tooth germs was higher in cap stage than in crown staged germs at both transcription and translation levels. They were strongly expressed in both ameloblasts and odontoblasts. Even though reduced enamel epithelium after enamel formation and inner enamel epithelium at the cap stage exhibited weak reactivity, strong reactivity was detected in dental follicles and perifollicular tissues surrounding cap staged germs. These results suggested that MMP-2 may involve degradation of the basement membrane during hard tissue formation, whereas MMP-9 might be involved in remodeling of follicular tissues.

• 전자공학회논문지CI
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• 제38권6호
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• pp.113-119
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• 2001

본 논문에서는 공간적 영상분할을 수행할 때 기존의 watershed 알고리즘과 그것의 수정 알고리즘에서 발생하는 과분할 문제를 해결하기 위한 개선된 watershed 알고리즘을 제안한다. 제안된 알고리즘의 주요 개념은 담수 단계에서 임계치보다 얄은 집수분지를 더 깊은 인접 집수분지에 병합하는 것이다. 따라서, 담수가 진행되는 과정에서 기존의 집수분지의 성장과 새로 담수가 일어나는 집수분지에 대한 추출이 이루어진다. 논문의 후반부에 몇 가지 MPEG 시험 영상을 사용하여 실험한 결과를 제시한다. 결론적으로, 제안된 알고리즘은 기존의 watershed 알고리즘에 아주 작은 계산시간을 추가함으혹서 적용된 임계치에 따라 좋은 분할결괴를 나타낸다.

• 농업과학연구
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• 제47권3호
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• pp.533-544
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• 2020

In this paper, we conducted a dynamic ex-post assessment on the grape business cessation support System. Based on the analysis results, in the short term, there was an increase in grape price due to a decrease in production and accompanying increases in the prices of consumption substitution items. However, in the long run, grape prices fell again due to an increase in grape production because of the entry of new grape farmers and the growth of adult grape trees. In addition, the analysis showed that the balloon effect caused by the conversion of crops caused indirect damage such as an increase in the production volume of substitution crops and a decrease in prices. When analyzing the social welfare measurement, the results showed that the support system for business cessation increased the overall social welfare due to an increase in producer welfare because of a price increase in the short term, but in the long term, both producer and consumer welfare decreased. In the end, it is necessary to review the system because the government's intervention may cause market distortion and inefficient resource allocation. Above all, it is necessary to minimize the indirect effect of the industry's contraction and balloon effect due to excessive business cessation. For this, conditional support should be provided in parallel with post management rather than unconditional support. In addition, it is necessary to provide a strategic support system that considers substitution items in addition to those items to be supported.

• Advances in nano research
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• 제3권2호
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• pp.97-109
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• 2015

Citrate ion is a commonly used reductant in metal colloid synthesis, undergoes strong surface interaction with silver nanocrystallites. The slow crystal growth observed as a result of the interaction between the silver surface and the citrate ion makes this reduction process unique compared to other chemical and radiolytic synthetic methods. The antimicrobial effects of silver (Ag) ion or salts are well known, but the effects of citrate coated Ag nanoparticles (CAgNPs) are scant. Herein, we have isolated biofilm causative bacteria and fungi from drinking water PVC pipe lines. Stable CAgNPs were prepared and the formation of CAgNPs was confirmed by UV-visible spectroscopic analysis and recorded the localized surface plasmon resonance of CAgNPs at 430 nm. Fourier transform infrared spectroscopic analysis revealed C=O and O-H bending vibrations due to organic capping of silver responsible for the reduction and stabilization of the CAgNPs. X-ray diffraction micrograph indicated the face centered cubic structure of the formed CAgNPs, and morphological studies including size (average size 50 nm) were carried out using transmission electron microscopy. The hydrodynamic diameter (60.7 nm) and zeta potential (-27.6 mV) were measured using the dynamic light scattering technique. The antimicrobial activity of CAgNPs was evaluated (in vitro) against the isolated fungi, Gram-negative and Gram-positive bacteria using disc diffusion method and results revealed that CAgNPs with 170ppm concentration are having significant antimicrobial effects against an array of microbes tested.