• 대한치과재료학회지
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• 제44권2호
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• pp.151-161
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• 2017

본 연구에서는 다양한 두께와 색조를 가진 레진 -나노세라믹 CAD-CAM block(RNB)의 시편을 이용하여 광중합 시 시편을 투과하는 광자의 수와 시편을 통과하는 빛의 양에 영향을 미칠 수 있는 반투명도 지수를 측정하고, 시편 하방의 이원중합 레진시멘트의 미세경도 측정을 통해 그 중합적 특성을 파악하였다. Lava Ultimate (3M/ESPE, St. Paul, MN, USA) 세라믹 시편을 A1, A2, A3색조 (HT (high translucency)와 LT (low translucency))로 각각 1, 2, 3, 4 mm 두께로 제작하였다 (n = 3). Photodiode detector (M1420, EG&G PARC, Princeton, NJ, U.S.A.)를 통해 시편을 통과하는 광자의 수를 측정하였고 spectrophotometer (SpectroPro-500, Acton Research, Acton, MA, U.S.A.)를 이용하여 시편의 반투명도 지수를 측정하였다. Stainless steel mold (6 mm 직경, 1 mm 두께)를 제작하여 이원중합 레진시멘트(Rely X ARC, 3M/ESPE, St. Paul, MN, USA)를 제조사의 지시대로 조작하여 적용 후 Mylar strip를 얹은 뒤 주입된 레진시멘트가 완전히 덮일 수 있도록 각 실험군의 시편을 위치시키고 광조사기로 40초간 광중합 하였다. 이후 24시간 동안 $37^{\circ}C$에 보관 후 미세경도를 측정하였다. 광자의 수는 HT, LT군에서 모두 세라믹 시편의 두께가 증가함에 따라 유의하게 감소하였고, A1 군이 A2군과 A3군에 비해 유의하게 적은 감소를 보였다 (p<0.05). 반투명도 지수는 HT, LT 그룹에서 시편의 두께가 증가함에 따라 유의하게 감소하였고 A1군이 A2군과 A3군에 비해 높은 값을 나타냈다 (p<0.05). HT, LT그룹 각각 두께가 증가함에 따라, 색조가 증가함에 따라 미세경도는 감소하였으며, 1 mm군과 4 mm군, 그리고 A1군과 A3군에서는 통계적으로 유의하게 감소하였다 (p<0.05).

• Transactions on Electrical and Electronic Materials
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• 제18권5호
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• pp.246-249
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• 2017

Pollution flashover of outdoor insulators is a common risk, which affects the safe operation of overhead transmission networks. Early electrical power systems, which feature insulators made from ceramic materials have been used all over the world with good performance. At present, non-ceramic insulators are in common use, as a result of their good electrical as well as mechanical properties. The aim of this paper is to discuss and compare the flashover performance of insulators typically used in power lines, such as, porcelain, ethylene-propylene-diene-monomer (EPDM) rubber, room temperature vulcanized (RTV) and high temperature vulcanized (HTV) coated silicone rubber. The effect of various parameters, including the severity of pollution, ice accumulation, and shade profile, are considered.. From the studies reviewed it was concluded that there is a distinct difference in the flashover voltages of different types of insulators, and the silicone provides the best flashover performance of all insulating materials.

• 로봇학회논문지
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• 제13권3호
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• pp.198-204
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• 2018

Quadrotor with limited flight time due to battery level can have the extended mission life by applying energy harvesting technology. Bio-inspiration from the birds' locomotion of flight and perch-and-stare can make energy consumption efficient, and energy harvesting technology can generate energy. In order to charge the battery with solar power, the drones are required to be in a position without shade. In the mountainous terrain, a novel mechanism is required in order to be located stably at the top of the tree or the inclined rock. In this study, we propose an analysis of the origami structure and the concept design of the perching mechanism with two stable equilibrium states. The origami structure composed of compliant material can be applied to the perching mechanism that can be locked passively. Moreover, the experimental results of the trajectory and perching test are discussed.

• 대한심미치과학회지
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• 제8권1호
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• pp.84-89
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• 1999

These days, Dental Technic has been contributed to make more delicating Dental Prosthesis Restoration for patient and dentist. Diagnostic wax-up and making Temporary Crown are emphasized as an important part of Dental Technic. Choosing suitable Material and working with various new Equipments like Microscope improve accuracy. Repeated practice by setting up an organized system gives better result. Also, Esthetic Prosthesis requires patient's appearance and personality as well as patient' age, sex, and shade so on. Moreover, the problem which occurs by the patient's oral condition ha to be discussed before taking final impression. At a time like this, Scientific-mind and Logical thought Ability should be considered the important issue for more progressive Dental Technic.

• 한국조경학회지
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• 제24권1호
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• pp.65-78
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• 1996

To study the temperature mitigation effects from urban green, several arrangements of green spaces were selected and air/ground temperatures were measured in Chongju city area. The results of this study can be summarized as follows; 1. It was found that the natural ground materials effect more affirmatively on the air and ground temperature than artificial ones do. The best results were recorded from the grass surface presenting highest mitigation effect and lowest daily temperature deviation. 2. Temperature mitigation effects of Tree-Shade on ground are different from season, ground material, and crown-size. Them most effects were found in interlocking block, the least in grass surface among recorded 2 seasons and 3 materials. In case of air temperature, the effects were more or less decreased in most cases. 3. From the survey, it was confirmed that the smaller urban greens can do its role of temperature mitigation as larger ones does. In case of this study, the effect was recorded about 2.3$^{\circ}C$.

• Restorative Dentistry and Endodontics
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• 제41권4호
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• pp.239-245
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• 2016

The purpose of this article was to review the changes in translucency of direct esthetic restorative materials after curing, aging and treatment. As a criterion for the evaluation of clinical translucency changes, visual perceptibility threshold in translucency parameter difference (${\Delta}TP$) of 2 was used. Translucency changes after curing were perceivable depending on experimental methods and products (largest ${\Delta}TP$ in resin composites = 15.9). Translucency changes after aging were reported as either relatively stable or showed perceivable changes by aging protocols (largest ${\Delta}TP$ in resin composites = -3.8). Translucency changes after curing, aging and treatment were perceivable in several products and experimental methods. Therefore, shade matching of direct esthetic materials should be performed considering these instabilities of translucency in direct esthetic materials.

• 대한치과보존학회:학술대회논문집
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• 대한치과보존학회 2003년도 제120회 추계학술대회 제 5차 한ㆍ일 치과보존학회 공동학술대회
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• pp.610-610
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• 2003

The purpose of this study was to propose a new dental color system through color evaluation of generally used dental composite and porcelain. In this study, Vita Omega 900 dental porcelain and 10 kinds of composite resins were used. A disk specimens(15mm diameter, 4mm thickness) of each material/shade combination were made. Resin compasite was condensed into Teflon mold and pressed between glass plates to flatten the surface. Pressed compasite was polymerized using an Optilux 501(Demetron, USA) for 200 seconds of each side.(중략)

• 한국자원식물학회지
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• 제13권2호
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• pp.124-130
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• 2000

우리 나라의 남부지방에서 고품질의 참당귀를 생산하고자 비가림하우스를 이용하여 차광재배로 하고현상을 방지한 후 멀칭재배을 실시하여 시험을 실시한 결과는 다음과 같다. 1 멀칭 종류별 토양의 습도와 지온은 무멀칭보다 멀칭재배에서 높았고, 특히 멀칭 중에서도 P. E.(polyethylene) 멀칭이 가장 높았다. 2. 잡초의 발생은 멀칭 종류별 투명 P. E. 멀칭재배에서 가장 적게 발생되었고, 투명 P. E. 멀칭재배에서는 많이 발생되었다. 3. 생육은 P. E. 멀칭재배가 짚멀칭이나 무멀칭보다 엽수가 많고 엽장이 커서 양호하였다. 4. 추대는 2∼5% 정도가 발생되었으며, P. E. 멀칭 재배에서 약간 많이 발생되는 경향이었다. 5. 수량은 P. E. 멀칭재배가 토양의 물리성이 좋아서 근수가 많고, 근장과 묘두직경이 커서 뿌리 생장이 양호하여 증수되었다.

• 한국자원식물학회지
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• 제13권1호
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• pp.11-17
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• 2000

우리 나라의 남부지방에서 고품질의 참당귀를 생산하고자 비가림하우스를 이용하여 차광재배로 하고현상을 방지한 후 멀칭재배을 실시하여 시험을 실시한 결과는 다음과 같다. 1. 멀칭 종류별 토양의 습도와 지온은 무멀칭보다 멀칭재배에서 높았고, 특히 멀칭 중에서도 P. E.(polyethylene) 멀칭이 가장 높았다. 2 잡초의 발생은 멀칭 종류별 검정 P. E. 멀칭재배에서 가장 적게 발생되었고, 투명 P E.멀칭재배에서는 많이 발생 되었다. 3. 생육은 P E. 멀칭재배가 짚멀칭이나 무멀칭보다 엽수가 많고 엽장이 커서 양호하였다. 4. 추대는 2∼5% 정도가 발생되었으며, P. E. 멀칭재배에서 약간 많이 발생되는 경향이었다. 5. 수량은 P E. 멀칭재배가 토양의 물리성이 좋아서 근수가 많고, 근장과 묘두직경이 커서 뿌리 생장이 양호하여 증수되었다. 한편, 검정 P E. 멀칭재배는 잡초 발생의 억제 효과가 뚜렷하여 P E. 멀칭재배시 노동력이 부족할 경우 적극 권장할 만한 멀칭재료로 생각되어진다.

• The Journal of Advanced Prosthodontics
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• 제8권1호
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• pp.16-20
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• 2016

PURPOSE. Polymer infiltrated ceramic network (PICN) materials, also called hybrid ceramics, are new materials in dental market. The manufacturer of the PICN material VITA Enamic suggests 3 different finishing procedures for this new material. In the present study, surface roughness and color differences caused from different finishing procedures of VITA Enamic were investigated. MATERIALS AND METHODS. 120 specimens were prepared in dimensions $2{\times}10{\times}12mm$ from VITA Enamic hybrid ceramic blocks with 'high translucency' and 'translucency 2M2' shades. The specimens were divided into 8 groups. For each group, different finishing procedures suggested by the manufacturer were performed. Surface roughness values were determined by a tactile portable profilometer. Color changes were evaluated using a clinical spectrophotometer. The data were analyzed using one-way ANOVA and Tukey's post-hoc comparison. The significance level was set at ${\alpha}=0.05$. RESULTS. The roughest surfaces were observed in Glaze Groups. Their surface roughness values were similar to that of the control group. Clinical Kit and Technical Kit groups did not show a statistically significant difference regarding surface roughness (P>.05). The largest color difference regarding ${\Delta}E_{00}$ was observed in Clinical Kit finishing groups. There were also statistically significant color changes between the groups (P<.05). However, all the groups showed clinically acceptable color change (${\Delta}E_{00}$<2.25) except Clinical Kit Groups (${\Delta}E_{00}$>2.25). CONCLUSION. Within the limitations of the present study, it may be suggested that finishing the VITA Enamic restorations by Technical Kit instead of Glaze and Clinical Kit gives better clinical performance in regard to surface roughness and shade matching.