• 한국경제지리학회지
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• 제12권4호
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• pp.597-612
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• 2009

이 연구에서는 도자기를 모티브로 한 일본의 한 농촌지역의 지역활성화운동의 사례를 살펴보고자 하였다. 특히 도자기가 지역활성화의 모티브가 된 역사와 핵심 활동가집단의 이념적 특성과 역할, 그리고 변화하는 현실에 대한 지역사회의 대응전략 등을 중점적으로 검토하였다. 마시코(益子)지역의 도자기산업은 19세기에 본격적으로 발전하기 시작하였고, 20세기에 접어들어서 여러 번 고비를 겪었지만 1960년대부터 민예운동과 결합되면서 비교적 안정적으로 도자기산업이 성장하였다. 이러한 마시코의 경험은 1980년대 말 이후 일본정부가 주력하였던 '위로부터의' 지역활성화운동과는 달리 자생적인 '밑으로부터의' 지역활성화운동이라고 평가할 수 있다. 또한 일본 전국에 유행처럼 번진 지역활성화운동들보다 선행하여 지역의 전통적이고 토착적인 문화적 자원을 적극적으로 활용한 사례라고 할 수 있다. 민예운동과 결합한 마시코의 지역활성화운동은 문화예술가 집단의 이념적 지도를 바탕으로 부단히 변화하는 현실의 상황들에 적극적으로 대응하여 왔다. 그 대표적인 예로 들 수 있는 것이 1950년대 중반부터 일용 도자기생산으로부터 민예품 도자기생산으로의 전환과 1960년대 중반의 도자기생산 및 판매의 핵심활동가집단의 공식적 출범과 산지직매체계의 구축, 그리고 1980년대 이후의 본격적인 민관협력 등이다. 현재까지 도자기를 모티브로 한 마시코의 지역활성화운동은 비교적 성공적인 길을 걸어왔지만, 지역사회의 다양하고 복잡한 최근의 내부 분화는 현실의 조건에 맞게 새로운 전통을 만들어가야 하는 상황에 놓여 있다는 것을 말해준다.

• 산업경영시스템학회지
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• 제46권3호
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• pp.15-22
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• 2023

BNKT Ceramics, one of the representative Pb free based piezoelectric ceramics, constitutes a perovskite(ABO3) structure. At this time, the perovskite structure (ABO3) is in the form where the corners of the octahedrons are connected, and in the unit cell, two ions, A and B, are cations, A ion is located at the body center, B ion is located at each corner, and an anion O is located at the center of each side. Since Bi, Na, and K sources constituting the A site are highly volatile at a sintering temperature of 1100℃ or higher, it is difficult to maintain uniformity of the composition. In order to solve this problem, there should be suppression of volatilization of the A site material or additional compensation of the volatilized. In this study, the basic composition of BNKT Ceramics was set to Bi_0.5(Na_0.78K_0.22)_0.5TiO₃ (= BNKT), and volatile site (Bi, Na, and K sources) were coated in the form of a shell to compensate additionally for the A site ions. In addition, the physical and electrical properties of BNKT and its coated with shell additives(= @BNK) were compared and analyzed, respectively. As a result of analyzing the crystal structure through XRD, both BNKT(Core) and @BNK(Shell) had perovskite phases, and the crystallinity was almost similar. Although the Curie temperature of the two sintered bodies was almost the same (TC = 290 ~ 300 ℃), it was confirmed that the d33 (piezoelectric coefficient) and Pr (residual polarization) values were different. The experimental results indicated that the additional compensation for a shell additive causes the coarsening, resulting in a decrease in sintering density and Pr(remanent polarization). However, coating shell additives to compensate for A site ion is an effective way to suppress volatilization. Based on these experimental results, it would be the biggest advantage to develop an eco-friendly material (Lead-free) that replaced lead (Pb), which is harmful to the human body. This lead-free piezoelectric material can be applied to a biomedical device or products(ex. earphones (hearing aids), heart rate monitors, ultrasonic vibrators, etc.) and skin beauty improvement products (mask packs for whitening and wrinkle improvement).

• The Journal of Advanced Prosthodontics
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• 제7권5호
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• pp.358-367
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• 2015

PURPOSE. The aim of this study was to evaluate the biaxial flexural strength (BFS) of one zirconia-based ceramic used with various veneering ceramics. MATERIALS AND METHODS. Zirconia core material (Katana) and five veneering ceramics (Cerabien ZR; CZR, Lava Ceram; LV, Cercon Ceram Kiss; CC, IPS e.max Ceram; EM and VITA VM9; VT) were selected. Using the powder/liquid layering technique, bilayered disk specimens (diameter: 12.50 mm, thickness: 1.50 mm) were prepared to follow ISO standard 6872:2008 into five groups according to veneering ceramics as follows; Katana zirconia veneering with CZR (K/CZR), Katana zirconia veneering with LV (K/LV), Katana zirconia veneering with CC (K/CC), Katana zirconia veneering with EM (K/EM) and Katana zirconia veneering with VT (K/VT). After 20,000 thermocycling, load tests were conducted using a universal testing machine (Instron). The BFS were calculated and analyzed with one-way ANOVA and Tukey HSD (${\alpha}$=0.05). The Weibull analysis was performed for reliability of strength. The mode of fracture and fractured surface were observed by SEM. RESULTS. It showed that K/CC had significantly the highest BFS, followed by K/LV. BFS of K/CZR, K/EM and K/VT were not significantly different from each other, but were significantly lower than the other two groups. Weibull distribution reported the same trend of reliability as the BFS results. CONCLUSION. From the result of this study, the BFS of the bilayered zirconia/veneer composite did not only depend on the Young's modulus value of the materials. Further studies regarding interfacial strength and sintering factors are necessary to achieve the optimal strength.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2015년도 자성 및 자성재료 국제학술대회
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• pp.104-104
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• 2015

• 대한치과보철학회지
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• 제39권2호
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• pp.197-207
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• 2001

Development of new ceramics and esthetic needs of patients increase the use of all ceramic restorations. Fractured teeth often need metal post and core as foundation for final restoration. When all ceramic restorations are planned, metal post and core may lead to compromised esthetics because of opacity and gray color of metal post and core. Many techniques have been proposed to solve this problem such as application of an opaque porcelain to the metal core or all ceramic post and core. This study was performed to evaluate effect on color of Empress 2 crown according to various post systems. Color was evaluated by the CIE $L^*a^*b^*$ systems and measured by spectrophotometer (Model CM-3500, Minolta, Japan). Specimens were divided into 4 groups as follows Group 1 : gold cast post specimen + Empress 2 crown specimen Group 2 : application of an opaque porcelain to gold cast post specimen + Empress 2 crown specimen Group 3 : cosmopost specimen + Empress 2 crown specimen Group 4 : In-ceram post specimen + Empress 2 crown specimen. The results obtained as follows, 1. $L^*$ Values showed that group 2, 3, 4 were higher than group 1 with significant difference and group 2, 3, 4 were not significantly different. 2. $a^*$ Values and $b^*$ values also showed that group 2. 3, 4 were higher than group 1 with significant difference and group 2, 3, 4 were not significantly different. 3. ${\Delta}E^* ab$ Values showed that ${\Delta}E^* ab$ 3 was the highest value and ${\Delta}E^* ab$ 5 was the lowest value.

• Journal of Korean Dental Science
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• 제8권1호
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• pp.28-35
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• 2015

Purpose: To investigate the influence of crown margin design on the stress distribution and to localize critical sites in maxillary canine under functional loading by using three dimensional finite element analysis. Materials and Methods: The bite force of 100 N, 150 N, and 200 N was applied with an angulation of $45^{\circ}$ to the longitudinal axis of tooth. Six models were restored with IPS e.max (Ivoclar Vivadent, Schaan, Liechtenstein) with a different margin design. With lingual ledge and various thicknesses, three different core ceramics were designed in each model. Result: In the core ceramic, the maximum tensile stresses were found at the labiocervical region. In the veneering ceramic the maximum tensile stresses were found at the area where the force was applied in all models. Conclusion: Shoulder and chamfer margin types are acceptable for all-ceramic rehabilitations. A ledge on the core ceramic at cervical region may affect the strength of all-ceramic crowns.

• 한국정밀공학회지
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• 제27권12호
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• pp.22-27
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• 2010

The usage of ultra-precision machining is increasing by the manufacturing of precision optical elements such as camera lens, laser printer, CD player, DVD and microscope parts etc.. The WC alloy material is in wide use by mold core to improve the productivity and accuracy in manufacturing those precision parts. The WC alloy mould core can be machined effectively by the parallel grinding process which is an excellent technique for manufacturing of surface profile hard to machining materials such as the hardened metal alloy, Ceramics, Glass and so on. Magnetic assisted polishing as a final polishing process has also been utilized to obtain ultra-precision mirror surface with the elimination of traces presented on ground surface. It is able to deduce the optimal ultra-precision machining conditions of the WC alloy material from the experiment and analyses results.

• 마이크로전자및패키징학회지
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• 제7권1호
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• pp.13-18
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• 2000

금속기판 위에 결합된 저온 소성 세라믹(low temperature co-fired ceramics on metal, LTCC- M)은 소성 후에 x-, y- 방향으로의 수축을 1% 이하로 억제할 수 있어 수동 소자를 내장하는데 매우 유리하며, 금속 기판 전체를 접지로 사용함으로써 노이즈를 감소시킬 수 있다. 본 고에서는 내부 실장 수동 소자별 특성차에 대하여 소개하고, 이러한 내부 실장 소자를 이용하여 실제로 제작된 PAM(power amplifier module)을 소개하였다. 내장된 수동 소자는 테스트 패턴 상에서 10~20%의 변화값을 보였으며 실제 모듈에 적용하여도 목표치에 부합하는 소자 구성이 가능하였다. 수동 소자가 내부에 실장됨으로써 신호 처리 시간을 감소시킬 수 있고, 납점의 감소로 공정을 단순화시킬 수 있을 뿐만 아니라 신뢰성 또한 증가시킬 수 있으므로 향후 RF모듈 외에 파워 및 고기능 소자 등 다양한 분야에 응용이 가능할 것이다.

• 한국산학기술학회논문지
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• 제21권3호
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• pp.335-341
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• 2020

본 연구의 목적은 shear bond strength을 이용하여 pressed lithium disilicate 전장도재와 zirconia core의 접착을 비교 분석하는 것이다. Zirconia blank(Zirtooth, HASS, Gangneung, Korea)에 각 pressed ceramic(IPS e.max Zirpress, Vita PM9, GC Initial IQ, HASS Rosetta UP)이 적용된 시편을 제작하였다(N=40). 전단결합강도를 비교 평가하기 위해 The Schmitz-Schulmeyer test method을 이용하였고 산출된 파괴하중의 값을 분석했다. 산출된 네 가지 전단결합강도 값들 간의 평균 비교는 일원분산분석(one-way ANOVA)을 통해 이루어졌고, Tukey의 사후검정을 실시하여 서로 간의 평균 차이가 통계적으로 유의함을 검증하였다. 또 파절면의 3D 분석을 통하여 파괴 표면을 관찰하여, 그 파괴 양상도 분류하였다. 실험군별 전단결합강도는 IPS e.max Zirpress 16.69±3.11MPa, VITA PM9 14.21±3.63MPa, GC Initial IQ 11.17±2.92MPa, HASS Rosetta SM 27.90±5.71MPa이었으며, Lithium disilicate ceramic veneer(HASS Rosetta SM)의 결합 강도는 다른 제품들보다 통계적으로 유의하게 높았다(p<0.05). 또, 파괴면의 유형 분류 결과, 모든 시편에서 cohesive 파괴는 관찰되지 않았고 주로 adhesive와 cohesive가 같이 조합된 파괴 유형이 관찰되었다. 본 연구 결과에 의해서 pressed lithium disilicate 전장도재가 기존의 pressed to zirconia system보다 나은 접착력을 보여주었다.

• 한국세라믹학회지
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• 제46권3호
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• pp.225-228
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• 2009

The processing and characterization of ceramic nanocomposites, which produce bulk nanostructures with attractive mechanical properties, have been emphasized and introduced at Prof. Mukherjee's Lab at UC Davis. The following subjects will be introduced in detail in Part II, III, and IV. In Part II, the paper will describe a three-phase alumina-based nanoceramic composite demonstrating superplasticity at a surprisingly lower temperature and higher strain rate. The next part will show that an alumina-carbon nanotube-niobium nanocomposite produced fracture toughness values that are three times higher than that of pure nanocrystalline alumina. It was possible to take advantage of both fiber-toughening and ductile-metal toughening in this investigation. In the fourth section, discussed will be a silicon-nitride/silicon-carbide nanocomposite, produced by pyrolysis of liquid polymer precursors, demonstrating one of the lowest creep rates reported so far in ceramics at the comparable temperature of $1400^{\circ}C$. This was first achieved by avoiding the oxynitride glass phase at the intergrain boundaries. One important factor in the processing of these nanocomposites was the use of the electrical field assisted sintering method. This allowed the sintering to be completed at significantly lower temperatures and during much shorter times. These improvements in mechanical properties will be discussed in the context of the results from the microstructural investigations.