SOFC 연결재용 Al이 도핑된 (La_0.8Ca_0.2)(Cr_0.9Co_0.1)O₃(LCCC)계 세라믹스의 합성 및 치밀화 특성

이호영,강보경,이호창,허영우,김정주,김재육,이준형,Lee, Ho-Young,Kang, Bo-Kyung,Lee, Ho-Chang,Heo, Young-Woo,Kim, Jeong-Joo,Kim, Jae-Yuk,Lee, Joon-Hyung 한국전기전자재료학회 2012 전기전자재료학회논문지 Vol.25 No.5

In the $(La_{0.8}Ca_{0.2})(Cr_{0.9}Co_{0.1})O_3$ (LCCC), which has been using as interconnector materials in SOFC, Al ions were substituted for Co because ionic radius of Al is similar to that of Co. Because of the almost identical ionic radius of Al and Co, the substitution was not thought to be affect the tolerance factor of LCCC, and the densification behavior, high temperature electrical conductivity and thermal expansion coefficient were examined as a function of Al concentration. In the cases of the x= 0 and x= 0.02 in $(La_{0.8}Ca_{0.2})(Cr_{0.9}Co_{0.1-x}Al_x)O_3$ (x= 0~0.1), the samples showed the relative densities above ${\geq}95%$ when those were sintered at ${\geq}1,350^{\circ}C$. In the case of the $x{\geq}0.06$ the sintered density deteriorated greatly at lower sintering temperatures. High temperature electrical conductivity of the samples decreased as the content of Al increased. Since the valence state of Al ion is unchangeable, while Cr or Co ions contribute to the electrical conduction by changing those valence states, Al substitution resulted in the decreased electrical conductivity. Al doping of LCCC was an effective way of decreasing the thermal expansion coefficient (TEC).

구리계 리드프레임/EMC 접합체의 파괴거동

이호영,유진,Lee, Ho-Young,Yu, Jin 한국재료학회 2000 한국재료학회지 Vol.10 No.8

구리계 리드페임의 표면에 흑생산화물을 형성시키기 위하여 알칼리 용액에 담궈 산화시킨후 EMC(epoxy molding compound)로 몰딩하였고 기계적 가공을 하여 SDCB(sandwiched double-cantilever beam) 및 SBN(sandwiched Brazil-nut)시편을 만들었다. SDCB와 SBN 시편은 리드프레임/EMC 계면의 접착력을 각각 준 mode I 하중 및 혼합모드 하중 하에서 파괴인성치로 측정하기 위하여 고안되었다. 파괴경로를 밝혀내기 위하여 접착력 츨정 후에 얻어진 파면에 대하여 glancing-angle XRD, SEM, AFM, EDS 및 AES를 이용하여 분석하였다. SDCB 실험 후의 파면은 파괴되는 양상에 따라 세 가지 형태로 나눌 수 있었으며, 각 형태는 리드프레임의 접착전 표면 산화물 형성 상태와 밀접한 관계가 있었다. SBN 실험 후의 파면은 균열에서 가까운 부분과 먼 부분으로 나누어지는 특징을 보였는데, 이는 동적 파괴 효과(dynamic fracture effect)에 기인하는 것이라 생각된다. 또한 위상각에 따라 확실히 다른 파괴 양상을 보였는데, 이는 위상각에 따라 mode II 성분이 변하기 때문으로 생각된다. Cu-based leadframe sheets were oxidized ic a hot alkaline solution to black-oxide layer on the surface and molded with epoxy molding compound(EMC), and finally machined to form sandwiched double-cantilever beam(SDCB) and sandwiched Brazil-nut(SBN)specimers to measure the adhesion strength of leadframe-EMC interface. The SDCB and the SBN specimens were designed to measure the adhesion strength in terms fracture toughness under puasi-mode I and mixed mode loadinf, respectively. After the tests, fracture surfaces were analyzed paths were observed in the SDCB-tested speciments, failure paths varied with crack speed and loading conditions.

Foraminifera from shell deposits of the Jindo Island

이호영,Lee Ho-Young The Korean Society Of Petroleum Geology 1993 한국석유지질학회지 Vol.1 No.1

진도에 분포되는 패각층의 유공충 군집은 온난환경에서 퇴적되었음을 지시한다. 총 12개의 표품에서 10속 11종의 저서성 유공충이 산출되었다. 이중에서 Cavarotalia annectens가 주요종으로 57에서 90퍼센트를 차지한다. 본역의 패각층은 유공충 군집으로 보아 흘로세 퇴적물이다. Foraminiferal assemblages from shell beds of Jindo Island indicate shallow water accumulation under warm to temperate condition near the mouth of a small estuary. 11 species of benthonic Foraminifera belonging to 10 genus have been extracted from 12 samples. Cavarotalia annectens dominates, accounting for 57 to 90 percent of the total fauna. The foraminiferal assemblages of the shell beds indicates Post-glacial sedimentation.

The Pronunciation of English Consonant Clusters by Koreans

이호영,Lee Ho-Young The Korean Society Of Phonetic Sciences And Speech 2000 말소리 Vol.40 No.-

한국어와 영어는 서로 다른 음소 배열 제약과 음운 규칙을 가지고 있기 때문에 영어 학습자들은 특정 영어 자음군을 정확하게 발음하는 데 어려움을 겪게 된다 따라서 이 논문은 영어 학습자들이 어떤 영어 자음군을 배우기 어려워 하고 왜 이러한 어려움이 생겨나는지 한국어와 영어의 음소 배열 제약과 음운 규칙을 비교해서 밝히는 것을 목적으로 한다.

산화처리된 구리계 리드프레임과 EMC 사이의 접착력 측정

이호영,유진,Lee, Ho-Young,Yu, Jin 한국재료학회 1999 한국재료학회지 Vol.9 No.10

Due to the inherently poor adhesion strength of Cu-based leadframe/EMC(Epoxy Molding Compound) interface, popcorn-cracking phenomena of thin plastic packages frequently occur during the solder reflow process. In this study, in order to enhance the adhesion strength of Cu-based leadframe/EMC interface, brown-oxide layer was formed on the leadframe surface by immersing of leadframe sheets in hot alkaline solution, and the adhesion strength of leadframe/EMC interface was measured by using SDCB(Sandwiched Double Cantilever Beam) and SBN(Sandwiched Brazil-Nut) specimens. Results showed that brown oxide treatment of leadframe introduced fine acicular CuO crystals on the leadframe surface and improved the adhesion strength of leadframe/EMC interface. Enhancement of adhesion strength was directly related to the thickening kinetics of oxide layer. This might be due to the mechanical interlocking of fine acicular CuO crystals into EMC. 본래 약한 구리계 리드프레임/EMC(Epoxy Molding Compound) 계면의 접착력은 솔더 리플로우 (solder reflow) 공정 중에 종종 박형 플라스틱 패키지의 팝콘 균열 현상(popcorn-cracking phenomena)을 일으킨다. 본 연구에서는 리드프레임/EMC 계면의 접착력을 향상시키기 위하여 리드프레임을 알칼리 용액에 담궈 표면에 brown oxide를 형성시켰으며, EMC로 몰딩(molding)하여 SDCB(Sandwiched Double Cantilever Beam) 시편 및 SBN(Sandwiched Brazil-Nut) 시편을 준비하여 접착력을 측정하였다. 리드프레임의 brown oxide 처리는 미세한 바늘모양의 CuO 결정들을 리드프레임 표면에서 형성시켰으며, 리드프레임/EMC 계면의 접착력을 향상시켰다. 접착력의 향상은 산화층의 평균두께와 직접적인 관련이 있었다. 이는 미세한 바늘모양의 CuO 결정들이 EMC와 기계적인 고착(mechanical interlocking)을 하기 때문으로 생각된다.

백내장수술 환자에게 적용된 모노비전(Monovision)에 대한 임상 연구

이호영,허준,Ho Young Lee,Jun Her,Ph,D 대한안과학회 2008 대한안과학회지 Vol.49 No.9

Purpose: To evaluate the clinical results of monovision treatment applied to cataract patients who planned to undergo phacoemulsification and posterior chamber intraocular lens (PC IOL) implantation. Methods: Phacoemulsificaiton and implantation of a monofocal PC IOL were performed in 40 patients between January 2005 and January 2006. Surgeries were performed on the dominant eye with the postoperative goals of emmetropia and on the nondominant eye with the postoperative goals of mild myopia. Patients' satisfaction, refractive change, and visual acuity were evaluated for at least 3 months after the surgery. Results: The mean postoperative uncorrected near visual acuity (UCNVA) of binocular eyes was 0.56±0.52, which was a statistically significant improvement compared with the mean preoperative UCNVA (P<0.001). The mean postoperative uncorrected far visual acuity(UCFVA) of binocular eyes was 0.70±0.34, which was a statistically significant improvement compared with the mean preoperative UCFVA (P<0.001). In all, 77.5% (31 of 40) of patients were satisfied with the results. Conclusions: Monovision induced by phacoemulsification and implantation of a monofocal PC IOL is suggested to be a good option in patients with presbyopia and cataract. J Korean Ophthalmol Soc 2008;49(9):1437-1442

인장하중하에서의 고분자/거친금속 계면의 파손에 대한 비교연구 II: 접착모델

이호영,김성룡,Lee Ho-Young,Kim Sung-Ryong 한국재료학회 2005 한국재료학회지 Vol.15 No.1

Copper based leadframe sheets were immersed in two kinds of hot alkaline solutions to form brown-oxide or blackoxide layer on the surface. The oxide-coated leadframe sheets were molded with epoxy molding compound (EMC). After post mold curing, the oxide-coated EMC-leadframe joints were machined to form sandwiched double-cantilever beam (SDCB) specimens. The SDCB specimens were used to measure the fracture toughness of the EMC/leadframe interfaces under quasi-Mode I loading conditions. After fracture toughness testing, the fracture surface were analyzed by various equipment to investigate failure path. An adhesion model was suggested to explain the failure path formation. The adhesion model is based on the strengthening mechanism of fiber-reinforced composite. The present paper deals with the introduction of the adhesion model. The explanation of the failure path with the proposed adhesion model was introduced in the companion paper.

기술과 자유로운 상상의 연결 패러다임

이호영,Lee, Ho Young 연세대학교 의과대학 2011 의학교육논단 Vol.13 No.2

The status of medical doctors is relatively high in society. However, in spite of this acknowledged status, physicians are not aware of the extent to which they have the ability to care for patients or how much effort they should make to meet people's expectations. Therefore, we should examine what society asks of doctors and how doctors need to be educated to meet the expectations of society. In this article, the author asserts that physicians need four skills. First, doctors should know how to speak and communicate. In the work of a doctor, language is the most important for tasks such as understanding texts, communication with patients, analyzing data, and starting new projects. Second, doctors should have intuition. In a doctor's medical judgment, intuition is very important and it can initiate from an educated guess. In other words, good intuition can be developed based on a good educated guess, which in turn can derive from one's explored knowledge, communication with one's inner dialogues, and good interpretation skill. Third, doctors should have creativity. Doctors should produce an image about patients from intuition, and those intuitions are based on creativity. Usually, students in medical school have creative ability; therefore, the instructor should facilitate their learning to connect this creativity to free imagination ability and medical skills. Fourth, doctors should be humane. Patients want to communicate with doctors about their disease and further about their lives. The reason why a humane doctor is important is that this humane approach itself could cure patients and reduce their pain. When a doctor's humane attitude is realized in the hospital, the patients and doctors could be pleased sincerely.

안구위축 혹은 변색된 실명안에서 Scleral Shell 의안 착용 결과에 대한 임상 연구

이호영,양재욱.Ho Young Lee. M.D.. Jae Wook Yang. M.D.. Ph.D. 대한안과학회 2008 대한안과학회지 Vol.49 No.7

Purpose: To show that scleral shells can be good cosmetic prostheses for phthisis bulbi or discolored blind eyes for which no evisceration or enucleation is indicated. Methods: Twenty patients with phthisis bulbi or discolored blind eyes were enrolled in this study. All patients were using scleral shells. We evaluated any complications induced by the scleral shells and the cosmetic results during the follow-up period. Results: The average central thickness of the scleral shell was 1.84±0.26 mm, and the average volume was 1.52±0.25 ml. The average difference in palpebral fissure width between the fellow eye and the eye with a fitted scleral shell was 0.8±0.62 mm. One patient complained about ocular irritation and difficulty in fitting but was satisfied with the cosmetic appearance. Conclusions: Fitting scleral cover shells over phthisis bulbi or discolored blind eyes without evisceration or enucleation could be a successful remedy for enhancing cosmetic appearance. J Korean Ophthalmol Soc 49(7):1041-1045, 2008

수종의 치근형 골내매식체와 조직간의 반응에 관한 조직학적 연구

이호영,김영수,Lee, Ho-Young,Kim, Yung-Soo 대한치과보철학회 1990 대한치과보철학회지 Vol.28 No.1

The success or failure of endosseous dental implants is related to the cellular activity at the implant surface. Success seems to be associated with the enclosure of the implant in a non-inflammed connective tissue or the formation of a direct bone implant interface. The purpose of this study was to examine the tissue reactions to the various implants at the submergible state in dog mandible. The $Br\"{a}nemark$, Core-Vent, Intergral, Bone spiral were selected for evaluation and also the Kimplant, Nephrite were used for the experimental study. After 4 months the animals were sacrificed. The interface zone between bone and implant was investigated using x-rays, light microscope, scanning electron microscope, transmission electron microscope. The following results were obtained from this study. 1. $Br\"{a}nemark$, Core-Vent, Kimplant, Integral showed no mobility and bone growth over the healing screws of the implants. Histologically most of the implant surface were covered by remodelled lamellar bone, and partly by a cellular layer or the thin fibrous tissue layer. 2. The Bone spiral showed no mobility and partially radiolucent line around the implant. The upper part of the implant was surrounded by a thin fibrous connective tissue and the middle, apical part of it were contacted with bone directly. 3. The Nephrite implant showed severe mobility and a radiolucent line around the implant. Histologically it showed mild inflammation and was surrounded by a fibrous connective tissue. 4. Scanning electron microscope showed that there was no amorphous ground substance in the Nephrite implant but the formation of ground substance over the collagen filaments in other implants. 5. Transmission electron microscope showed that collagen filaments were approached irregularly to the surface of all implants and in the $Br\"{a}nemark$, Core-Vent, Kimplant, Integral there was amorphous layer between the implant and the collagen filaments. It seemed to be ground substances.