• Proceedings of the Korean Fiber Society Conference
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• 2003.04a
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• pp.364-365
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• 2003

토목합성재료는 지반위에 전폭으로 연결되어 사용되고 하중도 전장 및 전폭으로 전달되므로 인장강도 역시 전장 및 전폭으로 시험하는 것이 바람직하나 시험기의 용량 및 시험편 파지장치의 기술적 제약 상 전폭시험이 불가능하다. 현재 국내에서는 그래브 및 스트립 상태인 소폭으로 시험한 후 m당 인장강도로 환산하여 시공설계에 적용하고 있으므로 실제 재료의 설계 시 인장강도와 측정된 인장강도간에 차이가 있다. 그러나 미국, 유럽 등에서는 광폭시험편을 준비하여 인장강도를 측정함으로써 이러한 오차를 최소화하고 있다. (중략)

• Electrical & Electronic Materials
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• v.22 no.9
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• pp.3-10
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• 2009

• Electrical & Electronic Materials
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• v.35 no.3
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• pp.4-14
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• 2022

• Journal of the korean academy of Pediatric Dentistry
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• v.50 no.3
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• pp.307-317
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• 2023

Due to increasing demand for aesthetics, zirconia crowns have become a popular choice for treating primary molars. However, there is limited literature available comparing the survival rates of zirconia crowns with those of other restorative materials. The objective of this study was to compare the 36-month survival rates of zirconia crowns and stainless steel crowns for proximal caries, as well as to analyze failure types associated with each crown type. Electronic medical records and radiographs of 1,061 primary molars from 498 patients treated with 2 types of prefabricated crowns at Chosun University Dental Hospital and 2 private dental clinics between 2017 and 2019 were collected and analyzed. The survival rate of zirconia crowns was found to be lower compared to that of stainless steel crowns. Regarding the groups without pulp treatment, the survival rate of stainless steel crowns was significantly higher than that of zirconia crowns. However, in the groups that received pulp therapy, no significant difference in the survival rates was observed between the two preformed crowns. Notably, abnormal root resorption or periapical lesions were identified as the primary cause of restorative failure in stainless steel crowns, whereas loss of restoration was the predominant cause in zirconia crowns. This study holds valuable implications for clinicians when selecting preformed crowns for primary molars.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.22 no.5
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• pp.317-331
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• 1989

Chaenogobius laevis inhabit brackish waters. Adult male protects egg mass laid under the stones. The egg with small oil globule varied from 3.40 to 4.04 mm in diameter. When water temperature is $22.0\~23.0^{\circ}C$, larvae hatched about 113 hours after fertilization. The newly hatched larvae reared for 33 days grow up to 12.10 mm in total length and developed to the jevenile. When larvae length attained about 8.0 mm, jaw bones were more rapidly ossified than vertebrae and cranium.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.12
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• pp.8447-8454
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• 2015

ISO 12215-5 standard describes allowable stress design specifications of monohull small boat with a length of hull between 2.5 m and 24 m constructed from fiber reinforced plastics, aluminium or steel alloys, glued wood or other suitable boat building material. If small boat hull is under 2.5m in overall length or nonstandard material is used as boat building material, structural reliability of small boat hull is assured by drop test specification, but not by structural design specification in accordance with ISO 12215-5. Drop test specification of boat hull can be applied to manufactured product. But it is difficult and complicated to apply drop test specification to structural design of boat hull. In this study, we present structural design method of polyethylene boat hull on the basis of longitudinal bending strength test specification.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.05a
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• pp.280-283
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• 1996

The electrical inductivity decreases when the content of NiO is used within 1 at% and increases when it's used more than that. Impedance spectrum seems to be one semicircle. The size of semicircle increases when the content of NiO is sued within 1 at% and decreases when it's used mor than that.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.300-302
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• 1996

Using the AC and DC methods we have studied th electrical properties of ZnO added TiO$_2$. The electrical conductivity of ZnO added TiO$_2$ was nearly unchanged with increasing the content of ZnO. Ac conductivity and conductance as a function of Frequency showed the similar trends. The impedance, admittance, and modulus spectrums were consistent with the results of DC conductivity.

• Ceramist
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• v.19 no.1
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• pp.62-67
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• 2016

지금까지 고용량 MLCC를 제조하기 위한 목적으로, MLCC용 유전체 재료의 기술 개발 동향을 재료적인 관점에서, 주로 BT 미립화에 따른 장점에 대해서 논하였다. 지금까지는 set 업체의 경박단소화, 다기능화 추세에 맞추어서 제품 개발이 이루어져 왔고, 이러한 제품을 완성시키기 위해서 재료 측면에서는 미립화가 지속적으로 이루어져 왔고, 미립화에 따른 유전율 감소 등의 부효과를 상쇄시키기 위한 미세구조 제어, 표면 개질 등의 기술개발도 동반하여 이루어져 왔다. 최근에는 이러한 추세가 전장 부품쪽에도 옮겨져서, 자동차에 채용되는 부품수 증가에 따른 소형화 needs가 지속적으로 커지고 있는 상황이다. 차량용 엔포테인먼트 시스템, 무인 주행 차량 등의 기술 상용화 시점이 얼마 남지 않은 시점에서 재료단에서 일반 IT 기기 대비, 신뢰성 특성이 강화되어야 하는 점을 고려해 보았을 때, 재료 개발의 중요성은 아무리 강조해도 지나치지 않을 것이다.

• Korean Journal of Materials Research
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• v.10 no.5
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• pp.360-363
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• 2000

Deformation in the hysteresis loop of $Pb(Zr,Ti)O_3$ (PZT) thin films with various Zr/Ti ratios has been studied by varying the top electrode preparation method and the annealing temperature. Pt/PZT/Pt capacitors was found to be positively poled due to dc plasma potential generated during reactive ion etch (RIE) of Rt. Internal field is formed by space charges trapped at domain boundaries. Aging phenomenon such as constriction in the middle of the hysteresis loop was observed in the PZT film with top electrode deposited by sputtering. Top electrode annealing restores the hysteresis loop by removing the space charges. As Zr/Ti ratio decrease, voltage shift increases and an-nealing temperature at which internal field disappears also increases.