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김학선,이원애,최진우,한원정,김은경 대한영상치의학회 2018 Imaging Science in Dentistry Vol.48 No.2
Synovial chondromatosis is a rare metaplastic disease affecting the joints, including the temporomandibular joint (TMJ). Since its symptoms are similar to those of temporomandibular disorders, a careful differential diagnosis is essential. A 50-year-old male patient was referred with the chief complaint of pain and radiopaque masses around the left TMJ on panoramic radiography. Clinically, pre-auricular swelling and resting pain was found, without limitation of mouth opening. On cone-beam computed tomographic images, multiple calcified nodules adjacent to the TMJ and bone proliferation with sclerosis at the articular fossa and eminence were found. T2-weighted magnetic resonance images showed multiple signal-void nodules with high signal effusion in the superior joint space and thickened cortical bone at the articular fossa and eminence. The calcified nodules were removed by surgical excision, but the hypertrophic articular fossa and eminence remained. A histopathological examination confirmed the diagnosis. The patient was followed up few months later without recurrence.
김학선 大田産業大學校 1995 한밭대학교 논문집 Vol.12 No.0201
This paper presents a tutorial treatment of the fundamentals of noise in solid-state analog electronic circuits. It is written about a basic knowledge of the theory of electronic noise and techniques for low-noise circuit design. The paper presents an overview of noise fundamentals, a description of noise models for passive devices and active solid-state devices, methods of calculating the noise performance of amplifiers, and techniques for minimizing noise in circuit design. The theory and methods are applicable to both discrete and integrated circuits.
PSPICE 시뮬레이션을 위한 연산증폭기의 매크로모델링에 관한 연구
김학선 한밭대학교 산업과학기술연구소 1993 논문집 Vol.1 No.-
In this paper, we described macromodelling for high level simulator. Basic building block for macromodel which is voltage adder, multiplier and divider is depicted, and operational amplifier macromodel using this technology is studied. for the PSPICE simulation, source code is implemented. We confirmed that both simulation result and measured data is very well fitted.
마이크로파 중합에 의한 의치상 레진의 물리적 성질에 관한 연구
김학선,김광남,장익태,Kim, Hak Sun,Kim, Kwang Nam,Chang, Ik Tae 대한치과보철학회 1990 대한치과보철학회지 Vol.28 No.2
The purpose of this study was to investigate the physical propertise and determine whether three were any differences in the amount of porosity of the denture base resins cured by microwave irradiation and conventional water bath heating. The resins used in this study were K-33 resin and Acron MC resin. The properties selected were transverse strength, Knoop hardness, and density. A ten-power eyepiece and scanning electron microscope(Magnification of ${\times}$ 30and ${\times}$150)were used to examine the specimens for porosity. Through analyses of the data from this study, the following conclusions were obtained. 1. Microwave energy can be effectively use dtopolymerize poly(methylmethacrylate) denture base resins. 2. In the transverse strength, K-33 resin cured by microwave irradiation was the first highest, water bath cured K-33 resin the second, microwave cured Acron MC resin the third, water bath cured Acron MC resin the fourth. 3. In the Knoop hardness, K-33 resin cured by microwave irradiation was the first hardest, water bath cured K-33 resin the second, water bath cured Acron MC resin the third, microwave cured Acron MC resin the the fourth. 4. No significant difference was found between the density of resin denture bases polymerized by either method. 5. K-33 resin showed the most porosity for the microwave curing. But there was no significant difference in the Acron MC resin and other curing method.
국소의치용 티나늄의 피로도 및 물리적 성질에 관한 연구
김학선,김광남,장익태,Kim Hak-Sun,Kim Kwang-Nam,Chang Ik-Tae 대한치과보철학회 1994 대한치과보철학회지 Vol.32 No.2
The purpose of this study was to compare the fatigue, physical properties, flexibility and surface roughness of titanium used in removable partial dentures with those of a type IV and alloy and a cobalt- chromium alloy. Fatigue testing subjected the test specimen to rapid cycling at a given stress until failure occurred by using a small-sized, electrodynamic type bending fatigue testing machine. The S-N curves for the framework materials were generated. For tensile testing, a tensile bar as described in the ADA Specification No.14 was subjected to tensile loading until failure occurred. Load-displacement curves were generated for 18 gauge round specimen and tapered half round specimen. Then the flexibilities were calculated. The surface roughnesses were compared by analyzer. Through analyses of the data, the following conclusions were obtained. 1. The fatigue property of titanium was higher than that of a type IV gold alloy$(p\leq0.05)$, but there was no significant difference between titanium and a cobalt-chromium alloy $(p\geq0.05)$. 2. The yield strength, the ultimate tensile strength and Victors hardness of titanium were higher than those of a type IV gold alloy but lower than those of a coalt-chromium alloy$(p\leq0.05)$. 3. The percentage of elongation and reduction of area of titanium were the highest $(p\leq0.05)$. 4. The surface roughness of titanium was the greatest$(p\leq0.05)$. 5. The flexibility of titanium was lower than that of a type IV gold alloy but higher than that of a cobalt-chromium alloy$(p\leq0.05)$.
흉강경을 이용한 척추측만증 수술에서의 굵은 강봉-다중축 나사못과 가는 강봉-단중축 나사못 비교
김학선,김주영,박진오,문성환,이환모,하중원,문은수,이수건,위환,김호중 대한척추외과학회 2008 대한척추외과학회지 Vol.15 No.1
Study Design:Prospective controlled cohort studyObjective:To analyze the clinical outcome of video-assisted thoracoscopic surgery (VATS) between two different types ofimplants.Summary of Literature Review:The problem of correction loss has been reported with VATS, and different screws and rodshave been developed to overcome this problem. Different implants will have varying effects in correctional outcome afterVATS. Materials and Methods:A total of 39 cases of idiopathic adolescent scoliosis treated with VATS between June 2001 and Janu-ary 2005 were included in the study (mono-axial screws and a 4.5 mm rod: thin rod group=19 cases; poly-axial reductionscrews and a 5.5 mm diameter rod: thick rod group=20 cases). All patients were followed for over 2 years postoperatively. Forthe comparison of surgical outcomes between the two groups, radiographic measurements were performed in the coronal andsagittal planes. Results:Preoperative scoliosis angle (thin rod group 49.8。, thick rod group 47.1。), age, BMI, Risser stage, union time, operativetime, and blood loss showed no statistical difference between the two groups. Postoperative average correction rate of scoliosisangle was 69% (15.8。) in the thin rod group and 70% (14.1。) in the thick rod group. However, correction rate after 2 years was51% (24.5。) in the thin rod group and 60% (18.7。) in the thick rod group, showing statistically significant difference. There wasa tendency toward correction loss in the thin rod group (8.7。vs. 4.6。p=0.0057). Conclusion:Postoperative correction rate was satisfactory in both groups. However, the thin rod group showed substantial cor-rection loss. Therefore, poly-axial screws and thick rods are more suitable in VATS correction of scoliosis.