치과용 수복재의 수분흡수도와 압축강도의 변화에 관한 연구

장우혁,최영철,Chang, Woo-Hyuck,Choi, Yeong-Chul 대한소아치과학회 2003 大韓小兒齒科學會誌 Vol.30 No.1

레진계열의 심미성 수복재는 구성성분에 따라 각기 다른 특성과 물리적 성질을 나타낼 뿐만 아니라, 수복물 주변의 환경도 물성에 많은 영향을 미친다. 특히 수분의 흡수는 수복재 물성 변화에 큰 역할을 하며, 재료의 조성과 친수성 정도, 경화기전, 침지기간과 배지 등의 다양한 요소와 관련되어 수복재마다 각기 다른 양상을 나타낸다. 본 연구의 목적은 임상에서 많이 이용되고 있는 레진계열의 수복물 중에서 복합레진, 레진변형 글라스아이오노머 및 콤포머의 침지기간에 따른 수분흡수도와 압축강도의 변화를 계측하여 비교하고, 수분흡수도와 압축강도 간에 나타나는 상관관계를 밝히고자함이다. 복합레진으로는 Z-100(3M, U.S.A.), 콤포머는 F-2000(3M, U.S.A.), 레진변형 글라스아이오노머는 Vitremer Restorative(3M, U.S.A.)를 이용하여 수분흡수도와 압축강도 측정을 위한 시편을 각각 제작하였다. 각 시편을 1일, 2주, 4주, 8주간 $37^{\circ}C$ 증류수에 넣어 보관한 후 수분흡수도는 침지 전과 후의 질량차를 부피로 나눈 값으로 산출하고, 압축강도는 Instron(Instron Corporation Headquarters, U.S.A.)을 이용하여 측정한 후 다음과 같은 결과를 얻었다. 1. 세 가지 수복재 모두 침지기간이 길어짐에 따라 수분흡수도가 증가하였으며 수분흡수의 대부분은 초기 2주 동안에 나타났다(P<0.001). 2. 레진변형 글라스아이오노머의 수분흡수도가 복합레진과 콤포머에 비해 상대적으로 크게 나타났다. 3. 세 가지 수복재 모두 침지시간에 따라 압축강도가 감소하였으며(복합레진과 콤포머: P<0.001, 레진변형 글라스아이오노머: P<0.05), 특히 복합레진이 다른 재료에 비해 가장 큰 감소 경향을 나타냈다. 4. 세 가지 수복재 모두 수분흡수도가 증가함에 따라 압축강도가 감소하였다(P<0.05). The aesthetic restorative materials are widely used in recent dentistry, showed not only the different quality between each component but also showed that the environment of the material has important effect on the physical properties of the material. Especially, when the restoratives are restored in the mouth, and since saliva is existing, the restoratives are always exposed to water and affected by the saliva. The purpose of this study was to research and compare the change of the degree of water sorption after water immersion of three types of the resin-based materials and the compressive strength, and observe the relation between the change of the water absorbing degree and the compressive strength. Z-100(3M, U.S.A) as a composite resin, F-2000(3M, U.S.A) as a compomer and Vitremer Restoratives(3M, U.S.A) as a resin-modified GIC were used, and each specimen was made to measure the water sorption and to evaluate the compressive strength. The specimens for measurement of the water sorption and the compressive strength were divided into 4 groups(1 day, 2 weeks, 4 weeks, and 8weeks). Each specimen was filled in the 30cc vial with 20cc of distilled water during the fixed amount of period in $37^{\circ}C$. The water sorption is decided by dividing the difference of weight before and after the immersion by the volume, and the compressive strength was measured by using the instron after the immersion. The following results were obtained ; 1. The more the water sorption increased, the more the immersion period of three restorative materials was long. And the most of water sorption was obtained during the first 2 weeks(P<0.001). 2. The water sorption of resin-modified GIC was higher than composite resin and compomer. 3. The more the compressive strength decreased, the more the immersion period of three restorative materials increased(composite resin and compomer: P<0.001, resin-modified GIC: P<0.05). Especially, the amount of the reduction in compressive strength of the composite resin was the highest. 4. The more the water sorption of all materials increased, the more the compressive strength decreased(P<0.05).

부정 접두사 in- 의 위치동화에 나타난 음성·음운론적 특성에 대한 언어 유형적 접근

장우혁(Chang, Woohyeok),심상완(Sangwan Shim) 한국음운론학회 2021 음성·음운·형태론 연구 Vol.27 No.2

In this paper, the presence and absence of place assimilation of the alveolar nasal in the negative prefix in- before stems which begin with a bilabial nasal <m> is discussed by comparing the prefix in Spanish with its occurrence in other languages (English, French, Italian, and Latin). In most languages, the nasal /n/ in the negative prefix in- undergoes place assimilation. However, it is interesting to note that this nasal sound in the Spanish negative prefix does not assimilate to a following bilabial nasal, so the geminate <mm> cannot be detected in Spanish. Phonetically, it has been revealed that the assimilated geminate nasal <mm>, which is produced after applying place assimilation to the nasal in the negative prefix, is not longer than a singleton <m>. Therefore, we can say that it is harder for listeners to perceive an ambisyllabic nasal [m] of the assimilated geminate in other languages than heterosyllabic nasals [n.m] in Spanish. For the phonological analysis, OT has been employed to categorize languages into two types (with or without place assimilation) by differentiating constraint rankings.

다중모드 통합시험환경을 이용한 계층구조 항공전자시스템의 검증

장우혁(Woohyuk Chang),박재성(Jae Seong Park),조영우(Young Wo Jo),변진구(Jinku Byun) 한국항공우주학회 2017 韓國航空宇宙學會誌 Vol.45 No.11

본 논문에서는 계층구조로 설계된 항공전자시스템의 체계적 검증을 위해 장비 모델을 활용하여 각 서브시스템 별 개별 검증, 다수 서브시스템들 간 통합 검증, 전체 시스템의 통합 검증 등으로 이루어진 단계적 검증 절차를 소개하였으며, 이를 기반으로 여러 단계의 시험이 1대의 통합시험환경으로 동시에 수행 가능한 다중모드 통합시험환경 개발 방안을 제안하여 기존의 순차적 시험 방식에 비해 시험 시간을 줄일 수 있음을 수학적으로 증명함으로써, 시험 효율성을 향상에 따른 검증 기간 단축과 비용 절감 효과를 입증하였다. In this paper, we first introduce a systematic verification procedure for hierarchically structured avionics system. By making use of equipment models, it can perform individual verifications of each subsystem, integrated verifications of multiple subsystems, and an integrated verification of a whole system. A multi-mode system integration laboratory is then proposed to make it possible to execute various individual or integrated verification tests at the same time. By mathematically proving that the proposed multi-mode system integration laboratory needs less verification time than the conventional verification methodology, it is expected to enhance the efficiency of the systematic verification procedure and as a result, reduce the overall verification period and costs.

낙설증후군의 임상양상

장우혁(Woo Hyok Chang),차순철(Soon Cheol Cha) 대한안과학회 2000 대한안과학회지 Vol.41 No.8

XML 기반의 데이터 저장관리를 위한 RDB2XML 변환 레퍼

장우혁(Woo-Hyuk Chang),김흥식(Heung-Shik Kim) 한국멀티미디어학회 2001 한국멀티미디어학회 학술발표논문집 Vol.2001 No.1

황반부를 침범한 열공망막박리 수술 후의 시력예후

장우혁(Woo Hyok Chang),박영훈(Young Hoon Park) 대한안과학회 2000 대한안과학회지 Vol.41 No.2

NRBC검사에 었어서 XE-2100과 Manual N-RBC Count의 비교

장우혁 ( Woo Hyuck Chang ),김천희 ( Chun Hee Kim ),조병철 ( Byeng Chul Cho ),지현숙 ( Hyun Sook Chi ) 대한임상검사과학회 2000 대한임상검사과학회지(KJCLS) Vol.32 No.3

Background : π1e presence of NRBC is normal for frrst several days in newbom. π1e presence of NRBC in the peripheral blood in adu1t is not associated with a specific single c1inical diagnosis, but in other situations the appearance of NRBC indicates disordered erythropoiesis. In many cases, NRBC in peripheral blood is an important marker of significant hematological and non-hematological diseases. NRBC should therefore be identified precisely Most automated hematology analyzers have a flagging system to indicate the presence of NRBC in a sample qua1itatively. πus makes it necessary to correct the WBC count by substrating the number of NRBC according to manual microscopy. But, manual microscopic examination has low sensitivity, specificity, and reproducibi1ity. Method Peripheral blood specimens anticoagulatεd with EDTA wεrε studiεd. 100 samples were analysed on XE-2100 and manual NRBC count. Result Manual microscopic reference NRBC counts of 10 patient specimens showed good correlation with XE-2100 (y= 1.2692x - 0.4722 ; r = 0.9354). But, the manual microscopic NRBC result counted 100 cells indicates low correlation (y=0.7787x + 7.6241 ; r = 0.8640). Performance for with-in day precison showed a mean coefficient of variation (CV) for the XE-2100 of = 5.4% (2.0-8.4%), with a mean CV for manual NRBC counts of 22.1 %. The between day precision using QC material (SF-CHECK), was 2.94% for low control 1.29% for normal control, and 1.63% for hlgh control. Conclusion : We conc1ude that thls automated method using XE-2100 was suitable for accurate NRBC counting in peripheral blood specimens with improved performance in terms of accuracy, reproducibi1ity, and sensitivity when compared to manual microscopic methods.

무인기 임무 계획을 위한 통합 프레임워크

장우혁(Woohyuk Chang),이동호(Dong Ho Lee),김상환(Sang-Hwan Kim) 한국항공우주학회 2019 한국항공우주학회 학술발표회 논문집 Vol.2019 No.11

무선 네트워크에서의 그룹 기반 협력 멀티캐스팅

장우혁(Woohyuk Chang),안우근(Woo-Geun Ahn),이주용(Ju Yong Lee) 한국통신학회 2010 한국통신학회 학술대회논문집 Vol.2010 No.11

몽골어 파열음의 음향적 특성이 몽골인 한국어 수준별 학습자의 한국어 파열음에 대한 음성인식에 미치는 영향

장우혁(Chang, Woohyeok) 한국몽골학회 2021 몽골학 Vol.- No.67

본 연구의 주된 목적은 몽골인 한국어 학습자가 후두 자질의 측면에서 삼원적 대립을 보이는 한국어 파열음을 어떻게 인식하는지를 알아보는 것이다. 30명의 몽골인 학습자가 음성인식실험에 참가하였는데 실험 참가자들은 다시 한국어 능숙도에 따라서 15명의 수준이 낮은 그룹과 15명의 수준이 높은 그룹으로 나누어졌다. 실험 결과에 따르면, 몽골인 참가자들이 그들의 한국어 능숙도와 상관없이 한국어 파열음 중에서 평음과 격음을 잘 구분하지 못 하는 것으로 드러났다. 이러한 사실은 한국어를 배우는 몽골인 학습자가 한국어 파열음을 정확히 인식하는데 필요한 VOT값과 F0값의 차이를 음향적 단서로 적절히 활용하지 못 한다는 것을 암시하고 있다. The main purpose of this study is to investigate how Mongolian learners of Korean perceive Korean plosives which has a three-way contrast in terms of laryngeal features. 30 Mongolian learners participated in speech perception tasks, and they were divided into two groups based on their proficiency of Korean: 15 participants for a low level and 15 for a high level. In the tasks, the Mongolian participants showed a poor performance in discriminating plain stops from aspirated ones, regardless of their Korean proficiency level. This implies that Mongolian learners of Korean are not able to utilize the differences in VOT and F0 values as acoustic cues to correctly distinguish the Korean plosive series. Given that Mongolian learners can successfully discriminate Mongolian plosives only with the VOT cue, their sensitivity to F0 has been diminished. Thus, this can have a negative effect on their perception of Korean plosives, which leads us to conclude that sources of Mongolian learners’ errors in discriminating Korean plosives involve failure to employ F0 as a perceptual cue to their perception of non-native sound contrast.