한국인의 하악 구치의 근관 형태에 관한 후향성 연구

정일영,금기연,이승종,이찬영 大韓齒科保存學會 1997 Restorative Dentistry & Endodontics Vol.22 No.2

A retrospective in vivo study of endodontically treated mandiblar molars was conducted. The radilographs and clinical records of mandibular molars that had been treated endodontically in the Dental hospital of Yonsei University from 1986 to July 1997 were reviewed and categorized. A total of 1751 cases were studied and following results were obtained. 1. The number of root canals in mandibular first permanent molar in d Korean population revealed three in 53.2%, four in 23.0%, two in 18.4%, C-shaped canal in 5.0%, and one in 0.4%. 2. In mandibular second molar, three canals was observed in 53.3%, four in 22.2%, two in 14.9%, C-shaped canal in 9.1%, and one in 0.6%. 3. In the results of the percentage of 4 canals of mandibular first molars at various age, before age 20, 37.7% was obtained whereas 19.3% after 30. 4. 7.94% of mandibular first molars examined were found to have three roots. 5. The mandibular second molar had C-shaped canals in 9.1%.

성상세포종에서 등급에 따른 p53 단백 발현의 차이

기근홍,양정원,이승학,이민오,성정희 조선대학교 2001 The Medical Journal of Chosun University Vol.26 No.1

Background and Objectives: Mutation or inactivation of the p53 is important mechanism in a wide variety of human tumors. The purpose of this study is to investigate the relationship between expression amount of p53 protein and the grade of astrocytic gliomas. Materials and Methods: This study analyzes 40 paraffin-embedded astrocytic glioma, including 10 cases of low grade, 20 cases of high grade, and 10 cases of maligant glioma (glioblastoma multiforme) were used to analyze the status of abnormal accumulation of wild type of p53 protein. The evaluation of the immunostaining result was based on the percentage of positive neoplastic cells. Results: Average positive cell rate of p53 protein were 4.2%, 35.4% and 16.2% in low grade astrocytoma, high grade astrocytoma and glioblastoma multiforme, respectively. Conclusion: p53 gene mutations were correlated with histologic grade of glial tumors. High grade and glioblastoma multiforme showed higher positive cell rate than low grade astrocytoma. These results suggest that the high positive rates of p53 protein is related to the poor prognosis.

불소의 농도와 Seed Material이 Crystal Growth에 미치는 영향

오승연,정일영,금기연,이찬영 大韓齒科保存學會 1997 Restorative Dentistry & Endodontics Vol.22 No.2

The present study was undertaken to investigate the crystal growth onto human enamel mineral and synthetic hydroxyapatite(HA) seeds in media resembling the enamel fluid composition. Effects of fluoride at high concentrations on the precipitation were also examined in a bench-top crystal growth model adopting a miniaturized reaction column. The Ca, P and F concentrations and pH values of the inlet and outlet solutions were determined. The recovered solid samples were weighed to assess the amount of minerals precipitated during the experimental period, and finally viewed under a scanning electron microscope. Remarkable findings were that 1) both biological and synthetic seeds with the same total surface areas yielded similar amounts of crystal growth, 2) the amount of crystal growth was accelerated in a manner depending of fluoride concentrations in the media, 3) SEM observations disclosed that without the addition of fluoride, precipitation of thin, plate-like OCP crystals became prominent, but by increasing the fluoride concentration(beyond 1ppm F), rod-like crystals having a pointed edge were most frequently observed, without and evidence for precipitation of the plate-like crystals. Furthermore, the dimension of rod-like crystals was increased in proportion of fluoride concentrations, 4) there was no difference in the morphological feature of precipitated mineral phase upon seeding between human enamel seed and synthetic HA seed. The overall results support the view that the seeded crystal growth model is of value to gain insight into the mechanism of enamel crystal growth under fluoride regimens.

기업의 자금 조달과 투자 결정, 배당의 상호작용에 관한 실증연구

김기웅,강호정,방승욱 한국항공대학교 경영연구소 2000 경영연구 Vol.7 No.2

본 연구는 기업의 자금 흐름 측면에서 주요 재무의사결정 변수간의 상호 관련성을 고려하여 각 변수간의 실증적인 관계를 파악하였다. 구체적으로 기업의 주요 재무 의사결정 변수인 주식 자금조달 금액, 부채 자금조달 금액, 투자금액, 배당금액을 내생변수로 선정하고 이들에 영향을 주는 외생변수들을 선정한 후에 이들간의 실증적인 관계성이 어떠한지 연립방정식 모형을 설정하였다. 검정가설은 각 내생변수간의 독립적인 관계를 귀무가설로 설정하고 이단계 최소 자승법과 삼단계 최소 자승법을 사용하여 실증분석을 수행하였다. 검증 결과 주요 재무변수간에는 독립적인 관계를 부정할 만한 증거를 얻을 수 없었다. 본 연구는 재무의사결정간의 실증적인 관계성을 파악함에 있어서 기업의 자금흐름 측면에서 상호 관련성을 인정하여 연립방정식을 사용한 점에 그 공헌점이 있다. This study focuses on the empirical relation among the variables considering interrelation of critical financing decision variables in the side of fund flow of firms. This study selects main financing decision variables i,e, financing amount by issuing stock, debt amount, dividend amount as endogenous variables and examines the empirical relation among exogenous variables influencing endogenous variables using the simultaneous equation model. We set the null hypothesis as independent relation among endogenous variables and tests by two stage least square and three stage least square method. The result of this study shows independent relation among critical financing decision variables. The contribution of this study is to use simultaneous equation model to examine empirical relation among critical financing decision variables considering interrelation in the side of fund flow of firms.

협심증 환자에서 경피적 관동맥 확장술 후의 QT간격분산(QT Dispersion)의 변화

최일준,이일수,이상곤,홍명기,박성욱,박승정,김유호 대한순환기학회 1998 Korean Circulation Journal Vol.28 No.9

Polaron Hopping in the K_(2)O · B_(2)O_(3) · V_(2)O_(5) Glasses

차유정,강재필,홍성덕,김복수,김영훈,서용문,송승기 명지대학교 자연과학연구소 2005 자연과학논문집 Vol.24 No.-

K_(2)O · B_(2)O_(3) · V_(2)O_(5) 계 유리의 조성비에 따른 밀도, 굴절율, 전이온도, 천이금속이온비율 등과 직류 전기 성질을 100~450K 온도영역에서 연구하였다. 실험결과를 비정질 반도체에 관한 전기전도에 대한 이론 모델을 이용하여 분석하였다. 고온 영역에서는 직류전도도의 온도 의존성을 Mott의 포논-도움껑충뛰기 전도모델로 분석할 수 있었다. 활성화에너지는 0.28~0.33 eV로 시료내 V_(2)O_(5) 의 양이 증가할수록 감소하는 경향을 보인다. 저온 영역에서 직류 전기전도도는 Mott의 가변거리 껑충뛰기(variable-range hopping)전기전도도와 잘 일치하며, N(E_(F))값은 국지화 상태에서와 같다. The dc conductivity of K_(2)O-B_(2)O_(3)-V_(2)O_(5) glasses has been investigated in the temperature range 100~450K and physical parameters such as density, refractive indices, glass transition temperature and fraction of reduced transition-metal ion, were observed for various compositions. The experimental results are analyzed with reference to theoretical models proposed for electrical conduction in amorphous semiconductors. The analysis shows that at high temperature region the temperature dependence of the dc conductivity is consistent with Mott's model of phonon-assisted hopping of small polarons. The values of activation energy are 0.28~0.33 eV and decrease with increasing V_(2)O_(5) content in the sample. The lowtemperature dc conductivity data can be well fitted to Mott's variable-range hopping conductivity and the values of N(E_(F)) are also reasonable for localized states.

특발성 좌심실빈맥(Idiopathic Left Ventricular Tachycardia)의 성공적인 전극도자절제술을 위해 단극전기도(Unipolar Electrogram)가 유용한가?

최기준,남기병,강덕현,홍명기,송재관,김재중,박성욱,박승정,박종훈,김유호 대한순환기학회 2000 Korean Circulation Journal Vol.30 No.4

신경회로망 제어기를 이용한 PID 파라미터 추정에 관한 연구

權重東,裵銀敬,金恩基,全基英,李承桓,吳鳳煥,李勳九,金容珠,韓慶熙 明知大學校 産業技術硏究所 2006 産業技術硏究所論文集 Vol.25 No.-

In this paper, supposed to solve these problem to PID parameters controller algorithm using ANN. In the proposed algorithm, the parameters of the controller were adjusted to reduce by on-line system the error of the speed of IM. In this process, EBPA NN was constituted to an output error value of an IM and conspired an input and output. The performance of the self-tuning controller is compared with that of the PH) controller tuned by conventional method (Ziehler-Nichols). The effectiveness of the proposed control method is verified thought the Matlab Simulink and experimental results.

용매의 선택에 따른 전도성 Polyaniline의 자기적 성질변화

오응주,서정선,노태호,류광선,정상국,송승기 명지대학교 자연과학연구소 1994 자연과학논문집 Vol.11 No.-

Polyaniline(emeraldine base:EB)를 pH에 따라 HCI로 1차 doping을 한후ESR을 사용하여 자기적 성질을 조사했다.또한 emeraldine base를 camphorsulfonic acid(HCSA), dodecylbenzene sulfonic acid(HDBSA)등의 산으로 1차 doping 시키고 이것을 m-cresol, acetic acid, 및 formic acid에 녹여 2차 doping을 한 후 SQUID 를 이용하여 자기적 성질을 측정하였다. Doping에 사용된 HCI용액의pH가 감소함에 따라 ESR 신호의 강도가 증가하였으며, 이로부터 doping에 따라 상자성을 나타나게 하는 화학종이 가타다는 것을아타내고 있다.m-cresol내에서 HCSA 및 HDBSA로 각각 doping된 EB-CSA/m-cresol 과 EB-DBSA/m-cresol 시료 무두 상자성을 나타내었고, 온도가 증가함에 따라 자하율값이 감소하는 경향을 나타내었다.χ?값은 2.18x10?과 7.87x10?emu/mol2-rings unit 보이며 두 스핀에 대한 Fermi 에너지 level(E?)에서의 상태밀도를 나타내는 N(E?)는 0.67과 0.24 상태(eV/2-rings unit?)로 나타났다.Camphorsulfonic ascid(HCSA)로 doping 된 EB를 m-cresol, acetic acid 및 chloroform 등 다른 용매에서 처리시 관찰된 자화율의 변화를 온도에 의존하지 않는 χ?값과 온도에 의존하는 χ? 값으로 구분하여 curie spin의 온도의존성을 규명하였다. Dependency of magnetic properties of polyaniline(emeraldine base:EB)on the pH of HCI used in doping was inverstigated by electron spin resonance spectroscopy. Emeraldine base doped with functionalized acid (primary dopant) such as camphorsulfonic acid (HCSA), dodecylbenzene sulfonic acid(HDBSA) was processed in various solvents (m-cresol, acetic acid, formic acid etc.)into homogeneous solution and free standing film and its magnetic properties were measured by SQUID. The intensity of ESR signal was increased with decrese in pH of HCL solution and paramagnetic behavior of doped polyaniline due to the formation of polaron upon doping could be confoirmed from these results. The same g value of 2.004±0.001 measured for all of the samples means that the chemical species which show paramagnetism are sasme. Polyanilines doped with HCSA and HDBSA in m-cresol showed paramagnetism and decrease in susceptibility with increase in temperature. χ? value was appered 2.18x10? and 7.87x10? emu/mol2-rings unit and N(E?) which is density of states at Fermi energy level for two spins was 0.67 and 0.24 state eV? 2rings unit? respectively. The changes in susceptibility of polyanilines doped with HCSA in m-cresol, acetic acid, formic acid etc. were divided into temperature independent χ? term and temperature dependent χ? term and temperature dependency of curie spin concentration was examined.

중증 근무력증 52례에 대한 임상적 고찰

박건주,하정상,이준,도현철,박승권,서상덕,기병수,김진국 영남대학교 의과대학 1996 Yeungnam University Journal of Medicine Vol.13 No.1

1985년 8월부터 1996년 1월까지 중증근무력증으로 진단받은 환자 52례에 대한 임상적 고찰을 통하여 다음과 같은 결론을 얻었다. 1. 전체 환자 중 남자가 19례(35.8%), 여자가 33례(64.2%)이넜고 11세에서 20세 사이가 12례(23%)로 가장 높은 빈도를 보였다. 2. 환자의 초기증상으로는 안검하수, 복시 등의 안구증상이 37례(71.2%)로 가장 많았고 modified Osserman의 분류에 따라서도 가장 증상이 가볍고 약물치료에 잘 반응하는 1군이 36례(69.3%)로 가장 많았다. 3. 환자가 호소하는 증상의 비특이성과 회복과 재발을 거듭하는 질병의 특성으로 인해 발병이후 진단될 때까지의 시간은 비교적 오래 걸렸고 1년이상 경과하며 진단된 경우도 16례(30.8%)나 되었다. 4. 자가면역질환이 7.6%에서 동반되었는데 갑상선기능 항진증이 2례(3.8), 인슐린의존형 당뇨 2례(3.8%)였고 종격동 전산화 단층촬영소견에서 흉선의 비대가 의심되었던 환자는 6례(11.5%), 흉선종이 발견 되었던 경우는 3례였다. 5. 환자의 치료는 대부분 항콜린에스테라제나 부신피질호르몬을 병용하는 내과적 치료를 하였으며 약물의 치료에 반응이 미비하거나 악화되는 경우 혹은 종격동 전산화 단층촬영상에서 흉선의 이상 소견이 보인 경우에 2례(3.9%)에서는 흉선절제술이, 1례(1.9%)에서는 혈장여과요법이 추가 되었고 흉선절제술과 혈장여과요법이 같이 병합 치료된 경우도 3례(5.9%)있었다. 6. 전체 환자중 2명에서 자연치유의 경과를 보였으며 이들은 모두 1군이였다. 그리고 흉선절제술과 부신피질 호르몬 투여로 완치된 예가 1례있었다. The authors experienced 52 patients with myasthenia gravis who were diagnosed at the Department of Neurology, Yeungnam University Hospital from August 1985 to January 1996. The following results were obtained through diagnostic evaluation and treatment. 1. The ratio of male to female was 1:1.7 and the most prevalent age group was second decade. 2. The most common initial presentation symptom was ocular(71.2%) and the peak incidence group was stage I(69.3%) according to the modified Osserman's classification. 3. In 16 patients(30.8%), it took more than a year to diagnose due to symptoms which were relapsed and remitting. 4. Of 52 patients, 2 cases were associated with thyroid disease(3.8%) and 2 with insulin-dependent diabetes mellitus(3.8%). 5. All of those who received anticholinesterase and corticosteroid therapy were improved with the exception of 5 cases which were improved after thymectomy and/or plasmapheresis. 6. Spontaneous remission was occured in 2 cases(3.8%) of ocular myasthenia gravis. And 1 case of group II was cured through thymectomy and long-term corticosteroid therapy.