• Journal of Technologic Dentistry
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• v.34 no.2
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• pp.83-93
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• 2012

Purpose: The objective of this study is to find out physical properties and the flexural strength changed by the low temperature degradation of the block which is needed to make bio-prosthetic dentistry which is better than feldspar affiliated ceramic made by building up ceramic powder and also to apply this to the clinical use of zirconia monolithic all-ceramic crown. Methods: Flexural strength of each sample was evaluated before and after the Low Temperature Degradation, and physical properties of the Tetra Zirconia Block containing 3mol % was evaluated as well. The average and standard deviation of each experimental group were came out of the evaluation. Statistical package for social science 18.0 was used for statistics. Results: The average density of the monolithic all-ceramic crown was $6.0280{\pm}0.0147g/cm$, the relative density was 99.01 %. When the sample was sintered at $1480^{\circ}C$ the diameter of average particle was $396.62{\pm}33.71nm$. All the samples had no monolithic peak after XRD evaluation but only had tetragonal peak. There were statistically significant differences in the result of flexural strength of the samples evaluated after and before the low temperature degradation, the flexural strength before the low temperature degradation was $1747.40{\ss}{\acute{A}}$, at the temperature of $130^{\circ}C$ the flexural strength after the low temperature degradation was 1063.99MPa (p<0.001). There was statistically significant difference in the result of strength of 1020.07MPa after the low temperature degradation at the temperature of $200^{\circ}C$ (p<0.001). Conclusion: The block which was made for this evaluation possesses such an excellent strength among dental restorative materials that it is thought to have no problems to use for tetragonal zirconia polycrystal.

• Korean Journal of Food Science and Technology
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• v.30 no.4
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• pp.811-816
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• 1998

A fermented vegetable kimchi swells in package bags often during distribution to comsumer after storage. The swelling has been prohibited by packaging the kimchi in a modified LDPE film that has been made by filling a ceramic powders disinfecting to lactic acid bacteria and growth enhancing to vegetables. The film exhibited higher permeability to carbon dioxide and ethylene than LDPE film. The tastes of kimchi in the film sustained its optical quality longer than that in LDPE film at room temperature.

• Ceramist
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• v.8 no.3
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• pp.25-30
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• 2005

최근 SOP에 대한 관심이 늘어나고 있으며 그에 따라 새로운 재료에 대한 관심도 증폭되고 있다. 예전의 단순한 신호 전달의 매개체 역할에서 벗어나 많은 수동 소자나 RF소자들을 내장하고 궁극적으로는 능동 소자까지 단일 기판위에 탑재하기 위해서는 기존의 RF 적인 전기적인 요구 특성 위에 많은 부가 특성들이 요구된다. 특히 SI이나 GaAs같은 능동 소자들과의 Assembly과정에서의 신뢰성을 확보하기 위해 낮은 선팽창 계수나 높은 탄성 계수 등의 기계적인 특성들이 요구되고 있으며 또한 점차 복잡한 회로 구조 등을 구현하기 위해 무수축이라는 새로운 공법 또한 요구되어 지고 있다. 그리고 사용주파수가 점차 높아짐에 따라 한편으로는 저유전율과 저손실의 재료가 요구되고 있으며 다른 한편으로는 embedded Capacitance의 요구에 맞춰 고유전율의 기판재료 또한 요구되어 지고 있다. 따라서 궁극적으로는 회로 구현의 목적에 따라 저유전율과 고유전율의 이종 재료의 접합이라는 문제 또한 자연스럽게 대두되고 있다. 이처럼 SoP에 대한 시장의 요구가 증가함에 따라 새로운 재료개발의 요구 또한 늘어나게 될 것으로 예상된다.

• Journal of electromagnetic engineering and science
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• v.10 no.3
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• pp.150-157
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• 2010

We proposed a $4{\times}8$ array antenna with aperture-coupled patch antenna elements. The antenna was designed for 60 GHz operation and fabrication on the low-temperature cofired ceramic(LTCC) substrate($\varepsilon_r$=5.8). The feedline with the stub was designed to enhance the radiating element bandwidth and the transition characteristics between the waveguide (WG) and microstrip line(MSL). Through the optimization of the antenna and feedline geometry, the antenna gain and the performance of the 10 dB bandwidth were 20.2 dBi and 13 % up, respectively. The measured results agreed with the simulated ones.

• Journal of Korea Society of Industrial Information Systems
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• v.19 no.1
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• pp.19-24
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• 2014

In this work, a compact patch antenna based on a low temperature cofired ceramic (LTCC) has been presented for V-band system-on-package (SoP) applications. In order to integrate it with transceiver block, a waveguide (W/G) to embedded microstrip line (eMSL) vertical transition was designed using slot-fed double stacked patch antennas for easy assembly and wide bandwidth. The $2{\times}2$ patch antenna integrating the transition was designed and fabricated in the 5-layer LTCC dielectrics. The whole size of the fabricated antenna including the $2{\times}2$ patches, transition and W/G was $20{\times}24{\times}5.39mm^3$. The fabricated antenna has achieved a 10 dB impedance bandwidth of 2.45 GHz from 61 to 63.45 GHz.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.139-142
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• 2001

As microeletronics technology continues to progress, there is also a continuous demand on highly integration and miniaturization of systems. For example, it is desirable to package several integrated circuits together in multilayer structure, such as multichip modules, to achieve higher levels of compactness and higher performance. Passive components (i.e., capacitors, resistors, and inductors) are very important for many MCM applications. In addition, the low-temperature co-fired ceramic (LTCC) process has considerable potential for embedding passive components in a small area at a low cost. In this paper, we investigate a method of statistically modeling integrated passive devices from just a small number of test structures. A set of LTCC inductors is fabricated and their scattering parameters (5-parameters) are measured for a range of frequencies from 50MHz to 5GHz. An accurate model for each test structure is obtained by using a building block based modeling methodology and circuit parameter optimization using the HSPICE circuit simulator.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.4
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• pp.32-39
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• 1998

Remez exchange algorithm was applied to realize an IF SAW filter for CDMA cellular phone systems. A SAW filter with withdrawal weighted transducers was simulated and then fabricated on 42.75.deg. ST-cut Quaritz wafer. Excellent agreement wasobtained between calculated andmeasured responses. Fabricated SAWfilterswere mounted on ceramic SMD package for reducing their size and volume. SAW filters were measured under matched circuit. As a result, 5 dB bandwidth of 1.32 MHz, 33dB bandwidth of 1.76 MHz, insertion loss of 13.8 dB and peak to peak ripple at passband of 0.26 dB were obtained. Linear group delay responses at passband were also obtained. These characteristics were good for practical use of IF SAW filter for CDMA system.

• Electronics and Telecommunications Trends
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• v.10 no.1 s.35
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• pp.47-57
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• 1995

최근 전자 및 통신기기에는 시스템의 소형화, 고기능 및 고신뢰도를 실현하기 위하여 하나의 기판위에 여러개의 chip을 장착하는 다중칩 패키지 기술이 사용되고 있다. 그러나 이로 인하여 기판 면적당 칩수의 증가로 power dissipation이 증가하게 되었으며, 이러한 power의 증가는 온도를 상승시켜서 시스템의 신뢰도를 저하시키는 원인이 되고 있기 때문에 이에 대한 열 해석이 요구되어진다. 따라서 본 고에서는 다중칩 패키지의 열 성능을 위하여 전도성이 좋은 세라믹 기판의 과도 온도 특성을 해석하고자, 전기적 유사 회로를 이용하여 thermal via가 없는 경우와 있는 경우에 대하여 열전달 특성을 고찰하였다. 그 결과 themal via에 의한 기판의 열전달 향상으로 다중칩 패키지의 동작 온도가 낮아짐을 알 수 있었다.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2003.09a
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• pp.19-39
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• 2003

Embedded Laminate Embedded RF Functional Blocks.Base Library of Laminate Embedded Filters and Baluns developed for 2.4GHz Applications -S-Parameters are provided at connection points -Utilizes a low cost 2 core construction.Statistical Variation Study in Report Phase.Measurements over variants show solid performance.Filters and Baluns are available for customer use.Laminate Embedded RF Functions - Various Filters, BALUNs, couplers, etc. for Bluetooth, 802.11, and Cellular.LTCC Embedded RF Functions - Various Filters, BALLNs, Diplexers, Antenna Switches, couplers, etc. for Bluetooth, 802.11, and Cellular.Eulbedded Passives - Various Inductor topologies Performance different than ideal or discrete inductor Must look at inductor performance in overall RF function - Working on embedded ceramic capacitors in laminate . Embedded Shields - Program in place to identify and define key design rules

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.4
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• pp.344-348
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• 2002

As microelectronics technology continues to progress, there is also a continuous demand on highly integration and miniaturization of systems. For example, it is desirable to package several integrated circuits together in multilayer structure, such as multichip modules, to achieve higher levels of compactness and higher performance. Passive components (i.e., capacitors, resistors, and inductors) are very important fort many MCM applications. In addition, the low-temperature co-fired ceramic (LTCC) process has considerable potential for embedding passive components in a small area at a low cost. In this paper, we investigate a method of statistically modeling integrated passive devices from just a small number of test structures. A set of LTCC inductors is fabricated and their scattering parameters (s-parameters) are measured for a range of frequencies from 50MHz to 5GHz. An accurate model for each test structure is obtained by using a building block based modeling methodology and circuit parameter optimization using the HSPICE circuit simulator.