• 한국결정성장학회지
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• 제29권6호
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• pp.329-337
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• 2019

스플린터(splinter) 및 판상(plate shape) 형상을 가지는 티탄산칼륨염(K₂O·nTiO₂, PT)을 합성하고 브레이크 마찰재의 보강재로 이용하여 마찰 특성을 평가하였다. 스플린터형 티탄산칼륨염을 합성하기 위하여 먼저 판상 형상을 가지는 사티탄산칼륨염(K₂O·4TiO₂, PT4)을 합성하고 칼륨 이온(K⁺)을 일부 산침출(acid leaching)하여 육티탄산칼륨염(K₂O·6TiO₂, PT6)으로 변환시킨 후, 800℃에서 열처리하여 스플린터 형상의 입자를 얻었다. 판상형 티탄산칼륨염을 합성하기 위해서 염화칼륨을 융제로 사용하고 마그네슘(Mg)을 일부 첨가하여 판상의 형상을 가지는 마그네슘티탄산칼륨염(K_0.8Mg_0.4Ti_1.6O₄, PMT)을 합성하였다. 얻어진 육티탄산칼륨염 및 마그네슘티탄산칼륨염 입자를 보강재로 이용하여 브레이크 패드 마찰재를 제작하고 1/ 5-스케일 다이나모미터(scale dynamometer)를 이용하여 마찰 마모 특성을 평가하였다. 평가 결과, 두 종류의 보강재가 유사한 마찰계수 및 Fade & recovery 특성을 보였으며 판상형 마그네슘티탄산칼륨염의 경우, 스플린터형 육티탄산칼륨염보다 우수한 내마모성을 보이는 것을 알 수 있었다.

• 한국재료학회지
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• 제27권3호
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• pp.132-136
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• 2017

We synthesized potassium hexatitanate, ($K_2Ti_6O_{13}$, PT6), with a non-fibrous shape, by acid leaching and subsequent thermal treatment of potassium tetratitanate ($K_2Ti_4O_9$, PT4), with layered crystal structure. By controlling nucleation and growth of PT4 crystals, we obtained splinter-type crystals of PT6 with increased width and reduced thickness. The optimal holding temperature for the layered PT4 was found to be ${\sim}920^{\circ}C$. The length and width of the PT4 crystals were increased when the nucleation and growth time were increased. After a proton exchange reaction using aqueous 0.3 M HCl solution, and subsequent heat treatment at $850^{\circ}C$, the PT4 crystal transformed into splinter-type PT6 crystals. The frictional characteristics of the friction materials show that as the particle size of PT6 increases, the coefficient of friction (COF) and wear amounts of both the friction materials and counter disc increase.

• International Journal of Precision Engineering and Manufacturing
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• 제4권1호
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• pp.30-36
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• 2003

Brittle materials such as glasses and ceramics, which are very weak under impact loading, show fragile failure mode due to their low fracture toughness and crack sensitivity. When brittle materials are subjected to impact by small spheres, high contact pressure occurs at the impacted surface causing local damage on the specimen. This damage is a dangerous factor in causing the final fracture of structures. In this research, the crack propagation process of soda-lime glass by the impact of small spheres is explained and the effects of several constraint conditions for impact damage were studied by using soda-lime glass; that is, the effects for the materials and sizes of impact ball, thickness of specimen and residual strength were evaluated. Especially, this research has focused on the damage behavior of ring cracks, cone cracks and several other kinds of cracks.

• 대한기계학회논문집A
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• 제26권1호
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• pp.153-159
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• 2002

Brittle materials such as ceramics and glasses show fragile fracture due to the low toughness and the crack sensitivity. When brittle materials are subjected to impact loading by small spheres, high contact pressure occurs to the surface of the specimen. Local damage is subsequently generated in the specimen. This local damage is a dangerous factor which gives rise to the final fracture of structures. In this research, impact damage of soda-lime glass plates by small spheres was evaluated by considering the effects of impact directions of indenter, pressure condition of specimen and residual strength after impact loading.

• 한국정밀공학회지
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• 제18권11호
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• pp.93-100
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• 2001

Brittle materials are very weak for impact because of typical characteristics which happen to be easily fractured with low fracture toughness and crack sensitivity. When brittle materials are subjected to impact due to small spheres, high contact pressure is occurred to impact surface and then local damage on specimen is developed, since there are little plastic deformations due to contact pressure compared to metals. This local damage is a dangerous factor which gives rise to final fracture of structures. In this research, the crack propagation process of soda lime glass by impact of small sphere is explained and the effects of the constraint conditions of impact spheres and materials for the material damage were studied by using soda-lime glass. that is the effects for the materials and sizes of impact ball, thickness of specimen and residual strength. Especially, this research has focused on the damage behavior of ring crack, cone crack and several kinds of cracks.

• Journal of Chest Surgery
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• 제49권5호
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• pp.408-412
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• 2016

A 50-year-old female patient with visual disturbances was referred for further evaluation of a heart murmur. Fundoscopy revealed a Roth spot in both eyes. A physical examination showed peripheral signs of infective endocarditis, including Osler nodes, Janeway lesions, and splinter hemorrhages. Our preoperative diagnosis was subacute bacterial endocarditis with severe aortic regurgitation. The patient underwent aortic valve replacement and was treated with intravenous antibiotics for 6 weeks postoperatively. The patient made a remarkable recovery and was discharged without complications. We report this case of subacute endocarditis with all 4 classic peripheral signs in a patient who presented with visual disturbance.

• PNF and Movement
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• 제16권2호
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• pp.195-205
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• 2018

Purpose: The purpose of this study was to demonstrate the effects of proprioceptive neuromuscular facilitation (PNF) stability techniques on walking speed, trunk stability, and balance in stroke patients. Methods: Ten stroke patients volunteered to participate in the study, and each of subjects was randomly assigned to either the stability technique (ST) group (n=5) or to the treadmill (TM) group (n=5). Each therapeutic exercise program was provided for 30 minutes a day, 5 days per week for 4 weeks. The ST group performed a PNF pattern combined with stabilizing reversal and rhythmic stabilization of the PNF stability technique. Walking speed (measured using a 10-meter walking test), trunk stability (TIS), and balance (BBS, FRT) were evaluated before and after training. All data were analyzed using SPSS version 18.0. The significance level for statistical inspection was set at 0.05. Results: Both groups showed improvements on the 10-meter walking test, the trunk impairment scale, the Berg balance scale, and the functional reaching test. Conclusion: PNF stability techniques are effective for improving trunk stability, balance, and walking speed in stroke patients. For stroke patients, PNF stability techniques are very useful and effective, including in clinical practice.

• 만화애니메이션 연구
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• 통권31호
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• pp.249-266
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• 2013

본 논문은 컴퓨터 게임에서 보여지는 게임 그래픽 유저 인터페이스의 미니멀리즘 사례를 연구하는 것을 목표로 하고 있다. 게임 그래픽 유저 인터페이스의 미니멀 경향을 분석하기 위해 분석대상으로 삼은 컴퓨터 게임들은 페르시아의 왕자, 미러스 엣지, 스플린터 셀, 기어즈 오브 워, 콜 오브 듀티4, 메트로 2033, 크라이시스2이며 위의 게임들은 미니멀리즘의 특성을 활용한 독특한 형태로 게임 그래픽 유저 인터페이스의 영역을 확장하고 있다. 1960년대 시각예술 분야에서 출현하여 예술전반에 다양한 영향을 끼치며 발전한 미니멀리즘은 시대적 요구에 부응하며 다양한 스타일로 표현되어 왔다. 따라서 본 연구에서는 미니멀리즘을 통해 게임 그래픽 유저 인터페이스에서 나타나는 최소화 현상을 바탕으로 미니멀리즘의 대표적 표현경향인 '단순성'과 '최소성'을 중심으로 게임 그래픽 유저 인터페이스에 나타나는 미니멀리즘의 영향력을 고찰하고자 한다.

• Tuberculosis and Respiratory Diseases
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• 제43권2호
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• pp.236-242
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• 1996

두개내 결핵성 육아종은 흉부, 복부 또는 요로 생식계에 있는 원발성 결핵으로 부터 결핵균이 혈행성으로 전파되어 생긴다고 하였으며, 주로 폐를 통해 침입하여 발생한다. 임상적으로 두통과 경련등의 증상을 보여 뇌종양의 양장으로 나타난다. 저자들은 속립성 결핵의 치료도중에 발생한 두통 및 현훈과 시력장애을 주소로 내원한 25세 여자환자의 뇌 자기공명영상으로 진단한 두개내 결핵성 육아종과 함께 안과 소견상 망막의 화염상출혈과 유두부종 및 시야검사상 양측두부의 반맹증과 중심암점으로 시신경의 결핵성 육아종을 의심하여 안구내의 steroid의 투약과 함께 항 결핵제제의 계속적인 투약으로 증상호전을 보인 증례을 경험하였기에 문헌고찰과 함께 보고하는 바이다.