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.

한국어의 변이음 규칙과 변이음의 결정 요인들

이호영,Lee Ho-Young 대한음성학회 1992 말소리 Vol.21 No.-

This paper aims to discuss determining factors of Korean allophones and to formulate and classify Korean allophonic rules systematically. The relationship between allophones and coarticulation, the most. influential factor of allophonic variation, is thoroughly investigated. Other factors -- speech tempo and style, dialect, and social factors such as age, set, class etc. -- are also briefly discussed. Allophonic rules are classified into two groups -- 3) those relevant to coarticulation and 2) those irrelevant to coarticulation. Rules of the first group are further classified into four subgroups according to the directionality of the coarticulation. Each allophonic nile formulation is explained and discussed in detai1. The allophonic rules formulated and classified in this paper are 1) Devoicing of Voiced Consonants, 2) Devoicing of Vowels, 3) Nasal Approach and Lateral Approach, 4) Uvularization, 5) Palatalization, 6) Voicing of Voiceless Lax Consonants, 7) Frication, 8) Labialization, 9) Nasalization, 10) Release Withholding and Release Masking, 11) Glottalization, 12) Flap Rule, 13) Vowel Weakening, and 14) Allophones of /ㅚ, ㅟ, ㅢ/ (which are realized as diphthongs or as monophthongs depending on phonetic contexts).

혼합 하중하에서의 고분자/거친금속 계면의 파손경로

이호영,김성룡,Lee Ho-Young,Kim Sung-Ryong 한국재료학회 2004 한국재료학회지 Vol.14 No.5

Copper-based leadframe sheets were oxidized in two kinds of hot alkaline solutions to form brown-oxide or black-oxide 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 Brazil-nut (SBN) specimens. The SBN specimens were used to measure the fracture toughness of the EMC/leadframe interfaces under mixed-mode (mode I + mode II) loading conditions. Fracture surfaces were analyzed by various equipment to investigate failure path. The results revealed that the failure paths were strongly dependent on the oxide type. In case of brown oxide, hackle-type failure was observed and failure path lay near the EMC/CuO interface with a little inclining to CuO at all case. On the other hand, in case of black oxide, quite different failure path was observed with respect to the distance from the tip of pre-crack and phase angle. Different failures occurred with oxide type is presumed to be due to the difference in microstructure of the oxides.

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.

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

국어 핵억양의 음향음성학적 연구

이호영,Lee Ho-Young 대한음성학회 1999 말소리 Vol.38 No.-

Korean intonation has been investigated mainly from the point of view of impressionistic phonetics and phonology. The purpose of this paper is to investigate Korean intonation especially nuclear tones, from the point of view of experimental phonetics. Since what we hear is not always the always as what we see in fundamental frequency contours, acoustic characteristics of Korean nuclear times are first discussed Based m quantitative data similar nuclear times are compared and the relationship between the nuclear ton and sentence type is investigated The relationship between the nuclear tone and the speaker's attitude is also discussed.

병행객체지향 언어에서 행위 방정식을 이용한 상속 변칙

이호영,이준,Lee, Ho-Young,Lee, Joon 한국정보통신학회 1999 한국정보통신학회논문지 Vol.3 No.3

상속 변칙이 발생하는 기본적인 이유는 병행객체에 대해 동기화 코드가 메소드 코드와 적당하게 분할되지 않을 때, 파생 클래스를 만들어내기 위한 코드의 확장이 슈퍼 클래스에 존재하는 동기화 코드와 메소드 코드를 변경하도록 할 때, 그리고 병행 객체지향 언어에서 상속성과 병행성이 결합할 때 발생한다. 강조할 점은 상속 변칙을 피하는 방법이다. 그래서 본 논문에서는 새로운 모델인 객체 모델을 제안하고 행위 방정식을 사용하여 병행 객체지향 언어에서 나타나는 상속 변칙의 문제를 최소화시키고자 한다. The fundamental reason why inheritance anomaly occurs is that for a concurrent object, when synchronization code is not properly separated from the method code, the extension of code to produce a derived class may force the change of both the synchronization code and the method code in the super class, and inheritance is integrated inheritance in a simple and satisfactory way within a concurrent object-oriented language. The main emphasis on how to avoid or minimize inheritance anomaly. Therefore, in this paper we propose a new model, object model, and will minimizes the problem of inheritance anomaly found in concurrent object-oriented programming languages using Behavior Equation.

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.

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