• 대한치과보철학회지
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• 제19권1호
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• pp.47-54
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• 1981

Dental porcelains are widely used for restorative material because of its excellent esthetic property. But according to contact with natural teeth or metal in oral cavity, the porcelain may be worn and may effect on masticatory physiology and prosthetic function. The purpose of this experiment was to study on wear of porcelain surface which treated in different method. Using the abrasion device which was designed and constructed by myself, the different porcelain surface were abraded by gold alloy, nickel-chrome alloy and natural teeth in order to compare roughness. Results were as follows. 1. The group of porcelain abraded by gold alloy showed less surface roughness change (t=2.92, p<0.05), and the group of porcelain abraded by natural teeth had high surface roughness. change (t=6.84, p<0.05). 2. According to the method of surface treatment, the surface roughness were very significant (F=9.12, p<0.05). 3. After abrading, the porcelain surface roughness change was very significant (F=54.49, p<0.05). 4. There was no significant between surface treatment method and the kind of abrading materials. (F=1.01, p>0..05). 5. The group of natural glazing had the most smooth surface ($2.1{\pm}1.13{\mu}m$).

• 한국실내디자인학회논문집
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• 제17권4호
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• pp.42-49
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• 2008

Design concepts of light can be divided into two respects, visual plastic and metaphysical meaning. The current research focuses on the second respect. The meaning of light is abstract characteristics(for example, divinity, spirituality, or image) ultimately expressed by visual plastic. Because it makes architectural space abundant, it have been expressed frequently in architectural space until now. The purpose of this paper is to conceptualize and explain and arrange the meanings of light in the category that have been expressed in architectural space from ancient to current. The method of this study is content analysis and case study, and this is supplement by theoretical consideration on the meaning of light(relationship between perception and meaning, elements to form meaning etc.). This study consists of three steps. Firstly, through the content analysis of existing literature and documents, 17 meanings of light are confirmed. Secondly, these 17 meanings are defined and explained in 3 categories(symbolic, esthetic, and experiential character). Thirdly, they are additionally explained and articulated by case study. In the result, various meanings of light that have been fragmentarily expressed in architectural space until now is clearly arranged at a glance. Those suggested design concepts will be basic conferential material, available to the interior designers and students who want to utilize the organised study concepts.

• 한국실내디자인학회논문집
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• 제19권1호
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• pp.169-179
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• 2010

Since modernization period thru Japanese colonial era the modern architect began to play a important role for Korean housing architecture. So called 'House as an Art Work', detached houses by prominent architects, belong to a meaningful sector in Korean modern housing architecture. The harmony with tradition was always big issue for such works. This study aims to understand how paradigms for tradition were interpreted with the changes of the time. The analysis showed various tryout by architects, that concretize traditional characteristics in their work. For example, traditional lifestyle were clearly reflected in the floorplan during 30's and 40's. In the 70's building mass and formative roof design were emphasized to present traditional image. As well as it represented primitive esthetic and vernacular decoration. In addition, expressive tendency, that demonstrates korean sentiment through material and its texture, got a preference. Since latter half of 80's some traditional architectural elements were modernized and space characteristics were newly created from acculturation. Furthermore the philosophy of "Subdivision of building wings and Emptiness" follows this trend. This type made a courtyard and connected articulated building masses each other. "Sympathy with Nature" were most essential for a traditional houses in contrast with western architecture. Many architects today make various method to bring nature into interior space and to contemplate nature In the house. Such kinds of adaptation to tradition could be understood as a unique process to manifest identity of Korean modern houses.

• Imaging Science in Dentistry
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• 제50권2호
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• pp.175-180
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• 2020

Purpose: In this study, we used ultrasonography to monitor the use of hyaluronic acid (HA) as a filler in the face for esthetic reasons. We monitored changes in the filler shape, distribution, and relationship with adjacent anatomical structures over a 180-day period. Materials and Methods: Two patients each received an ultrasound-guided injection of HA, with different products and application sites for each patient. In 1 patient, the injection was administered in the angle of the mandible, while in the other, it was administered in the zygomatic region. The injection sites were monitored via ultrasonography at 24 hours, 30 days, and 180 days, at which times the imaging characteristics of the filler were observed. All injections were performed by the same professional, as were the ultrasound exams, which were conducted using the same equipment. Results: In both cases, the HA fillers were visualized using ultrasound at all time points. Some differences were observed between the cases in the images and the distribution of the pockets of filler. In 1 case, the filler appeared as a dark hypoechoic region with well-defined contours, and the material was observed to have moved posteriorly by the 180-day mark. In the other case, the material appeared hyperechoic relative to the previous case and presented no noticeable changes in its anteroposterior distribution over time. Conclusion: Based on these 2 cases, ultrasonography can be a complementary tool used to monitor facial fillers over the long term, allowing for the dynamic observation of different fillers.

• 한국융합학회논문지
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• 제6권4호
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• pp.9-14
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• 2015

본 논문은 기타의 목 부분의 형상에 따라 가해지는 힘에 의한 휘어짐의 문제를 해결하기 위한 것으로, 기존의 기타를 보강하여 실제 사용 시, 하중에 취약한 부분을 파악하는 방법을 연구하였다. 본 연구에서는 실제 기타에 적용되는 목재의 물성치를 연구모델에 적용하고 모델링 한 후, 유한요소해석을 수행하였다. 본 논문의 연구를 통해 나온 결과를 사용하여 기존의 기타의 문제로 지적되어온 휨과 파손에 대한 기반자료를 얻을 수 있을 것으로 사료되며 이를 보강 할 수 있는 디자인을 연구하여 그 기타를 개선하고자 한다. 개선된 연구모델에 대한 결과를 토대로 실제 설계에 응용한다면 휨과 파손을 방지하여 내구성을 향상시킬 수 있으며 디자인 면에서의 융합기술로의 접목도 가능하며 미적인 감각을 나타낼 수 있다.

• 대한치과보철학회지
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• 제46권3호
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• pp.227-237
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• 2008

STATEMENT OF PROBLEM: Zirconium oxide can be a substitute to titanium as implant materials to solve the esthetic problems of dark color in the gingival portion of implant restorations. PURPOSE: This study was performed to define attachment and growth behavior of osteoblast- like cells cultured on grooved surfaces of zirconium oxide and evaluate the genetic effect of zirconium oxide surfaces using the reverse transcriptase-polymerase chain reaction (RT-PCR). MATERIAL AND METHODS: MC3T3-E1 cells were cultured on (1) commercially pure titanium discs with smooth surface (T group), (2) yttrium-stabilized tetragonal zirconia polycrystal (Y-TZP) with machined surface (ZS group), and (3) Y-TZP with $100{\mu}m$ grooves (ZG group). Cell proliferation activity was evaluated through MTT assay and cell morphology was examined by SEM. The mRNA expression of Runx2, alkaline phosphatase, osteocalcin, TGF-${\beta}1$, IGF-1, G3PDH in E1 cells were evaluated by RT-PCR. RESULTS: From the MTT assay, after 48 hours of adhesion of MC3T3-E1 cells, the mean optical density value of T group and ZG group significantly increased compared to the ZS group. SEM images of osteoblast-like cells showed that significantly more cells were observed to attach to the grooves and appeared to follow the direction of the grooves. After 24 hours of cell adhesion, more spreading and flattening of cells with active filopodia formation occurred. Results of RT-PCR suggest that T group, ZS group, and ZG group showed comparable osteoblast-specific gene expression after 24 hours of cell incubation. CONCLUSION: Surface topography and material of implants can play an important role in expression of osteoblast phenotype markers. Zirconia ceramic showed comparable biological responses of osteoblast-like cells with titanium during a short-time cell culture period. Also, grooves influence cell spreading and guide the cells to be aligned within surface grooves.

• 대한치과보철학회지
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• 제46권3호
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• pp.298-306
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• 2008

STATEMENT OF PROBLEM: Effect of surface treatment of ceramic under loading does not appear to have been investigated. PURPOSE: The aim of this study was to investigate the effect of surface treatment of esthetic ceramic, which is performed to increase the bonding strength, on the fracture stress under controlled cyclic loading condition. MATERIAL AND METHODS: Sixty 1.0 mm-thick specimens were made from Mark II Vitablocs (Vita Zahnfabrik, Germany) and divided into 3 groups: polished (control), sandblasted, and etched. Specimens of each group were bonded to a dentin analog material base including micro-channels to facilitate the flow of water to the bonding interface. Bonded ceramics were cyclically loaded with a flat-end piston in the water (500,000 cycles, 15Hz). Following completion of cyclic loading, specimens were examined for subsurface crack formation and subsequent stress was determined and loaded to next specimen by the staircase method according to the crack existence. RESULTS: There were significant differences of mean fatigue limit in the sandblasted (222.86 ${\pm}$ 23.42 N) and etched group (222.86 ${\pm}$ 14.16 N) when compared to polished group (251.43 ${\pm}$ 10.6 N) (P<.05; Wald-type pair-wise comparison and post hoc Bonferroni test). Of cracked specimens, surface treated group showed longer crack propagation after 24 hours. All failures originated from the radial cracking without cone crack. Fracture resistance of this study was very low and comparable to failure load in the oral cavity. CONCLUSION: Well controlled cyclic loading could induce clinically relevant cracks and fracture resistance of Mark II ceramic was relatively low applicable only to anterior restorations. Surface treatment of inner surface of feldspathic porcelain in the matsicatory area could influence lifetime of restorations.

• The Journal of Advanced Prosthodontics
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• 제9권5호
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• pp.387-393
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• 2017

PURPOSE. Beverages may affect the translucency of esthetic dental restorative materials.The aim of the present study was to investigate the effects of coffee and red wine on the translucency of a PICN material with two translucency levels, and finished with different methods. MATERIALS AND METHODS. 2M2 high translucent and translucent VITA Enamic hybrid ceramic blocks were investigated. Rectangular specimens with the dimensions of $12mm{\times}14mm{\times}2mm$ were prepared. The specimens were finished and polished with different methods as suggested by the manufacturer. The translucency parameters of the specimens were evaluated before and after 24 hours, 7 days, and 28 days immersion in distilled water, coffee and red wine. Translucency parameters were measured using a portable spectrophotometer. RESULTS. At the end of 28 days, there was no statistically significant difference between the groups of specimens kept in coffee (P>.05). In the red wine groups, there was a statistically significant difference between the control group and all other groups (P<.05) at the end of 28 days. CONCLUSION. The translucency of hybrid ceramic for a restoration may not be important regarding the effects of coffee on translucency change because the specimens with different translucencies and finishing methods that were immersed to coffee had similar translucency parameters at the end of 28 days. The translucency of hybrid ceramic may be important in the case of red wine, however, since the results showed that highly translucent specimens exposed to red wine demonstrated better translucency parameters than specimens made from translucent blocks at the end of 28 days.

• 대한치과보철학회지
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• 제46권6호
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• pp.577-585
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• 2008

STATEMENT OF PROBLEM: The discoloration of anterior teeth restoration is one of the material problems demanding retreatment. OBJECTIVES: To evaluate the color stability and affecting factors on esthetic restorative materials when subjected to accelerated aging. MATERIAL AND METHODS: This study was conducted using porcelain disks (IPS Empress 2-glazed, IPS Empress 2-polished), direct restorative resin disks (SYNERGY Duo) and indirect restorative resin disks (Sinfony, TESCERA ATL). Accelerated aging was done by precipitating the specimens in 38.C distilled water and irradiating with xenon light, and the total irradiation was 397.98 KJ/mm. Color and microhardness change of the specimens were measured before accelerated aging and after 100 hours, 200 hours and 300 hours of accelerated aging, and Surface of the specimens were examined with SEM before and after 300 hours of accelerated aging. RESULTS: 1. After 300 hours' accelerated aging, a ${\Delta}E$ value was 3.3 or lower in IPS Empress 2-glazed, IPS Empress 2-polished and Sinfony. 2. After 300 hours' accelerated aging, gloss was lost and surface changes including microcracks were observed in TESCERA ATL and SYNERGY Duo, and color changes of them ranged between 3.58 and 6.40 ${\Delta}E$ units. 3. During 300 hours' accelerated aging, the microhardness of surface was increased by 3.21 - 19.64% in all kinds of composites resin. CONCLUSION: After 300 hours' accelerated aging, SEM images IPS Empress 2-glazed, IPS Empress 2-polished and Sinfony showed little morphological change and their color changes were considered to be clinically acceptable. And there was significant correlation between microhardness changes and color changes of composites (P < .05).

• Restorative Dentistry and Endodontics
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• 제19권2호
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• pp.447-459
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• 1994

The purpose of this study is to evaluate of shear bond strength of light-curing composite resin to light-curing glass ionomer cement. Composite resin and glass ionomer cement have been widely used as an esthetic filling materials in dental clinics. To achieve better clinical results, sandwich technic was developed with conpensating for disadvantages of these two materials. Especially, light-curing glass ionomer cement provided greately improved bonding strength of teeth or composite resin, and then excellent clinical results can be acquired. In this study, 6 commercial light-curing glass ionomer cements(3 commercial restorative materials : Fuji II LC, Variglass VLC, Vitremer, and 3 commercial lining materials : Fuji Lining LC, Baseline VLC, Vitrebond) were devided two groups. According to manufacturer's appointment, no surface treatment was referred to N groups. Supposing. of clinical practice, surface grinding with water spray at 320 grit sand paper, 40 seconds etching with 37% phosphoric acid, 20 seconds washing, 20 seconds air drying was referred to N groups. Totally 12 experimental groups were devided, and all 120 specimens from 10 specimens of each groups were made. After light-curing composite resin was bonded to light-curing glass ionomer cement, shear bond strength was tested by Instron universal testing machine between glass ionomer cement and composit resin. The data were analyzed statistically by Student's t-test and ANOVA. The obtained results were as follows; 1. In light-curing glass ionomer cement, restorative materials showed higher shear bond strength to composite resin than lining materials(p<0.05). 2. Variglass VLC of restorative material group and Baseline VLC of lining material group have highest shear bond strength to composite resin(p<0.001). 3. In light-curing glass ionomer cement, surface grinding and acid etching reduced shear bond strength to composite resin(p<0.001)}. 4. VGN group 1s highest shear bond strength to composite resin, VBE group is lowest shear bond strength to composite resin(p<0.001).