• Journal of the Korean Academy of Esthetic Dentistry
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• v.6 no.1
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• pp.18-31
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• 1997

By the concerns of esthetic restoration were increased recently. many all ceramic crowns were developed. But they except In-Ceram Alumina were used only single crown. In-Ceram Alumina, developed by Dr. Sadon, was revealed to have high flexural Strength(450MPa). So it could be used not only anterior bridges but also posterior bridges. But In-Ceram Alumina was seen to be opaque, a little green color in transillumination light by high content of alumina oxide(85%). So new all ceramics with high strength and high translucence were needed. Spinell($MgAl_2O_3$) have a high melting point, high flexural strength, low heat conductivity, high light conductivity. In-Ceram Spinell offers glasslike light transmission by using the spinell cores instead of the alumina cores. And they have a high translucency like to natural tooth, an excellent margin integrity and a high strength(350MPa). The purposes of this study are 1) to know about the construction method of In-Ceram Spinell System, 2) to investigate the its clinical possibiliy through patients and literature reviews.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1881-1883
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• 2001

We manufactured a micro CPL by LlGA process, a new conceptual ultra-fine and precise forming method, using X-ray lithography process. We fabricated a BN X-ray mask having properties of good X-ray transmittance and large mechanical strength. Micro CPL was manufactured by dividing into an upper plate and a low plate. Each of plates was bonded by Ag paste screen printing. The upper plate was fabricated on glass wafer to observe flow and phase transformation of cooling solution. The lower plate was manufactured by Cu electroplating for good heat transmission. Precision of inner Parts, micro pin and micro channel, of manufactured micro CPL is under ${\pm}2{\mu}m$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.111-111
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• 2010

The mold transformers have been widely used in underground substations in large building and have some advantages in comparison to oil-transformer, that is low fire risk, excellent environmental compatibility, compact size and high reliability. In addition, the application of mold transformer for outdoor is possible due to development of epoxy resin. The mold transformer generally has cooling duct between low voltage coil and high voltage coil. A mold transformer made by one body molding method has been developed for small size and low loss, but it needs some cooling method because heat radiation between each winding is difficult. In this paper, the temperature distribution and thermal stress analysis of H class 100kVA pole cast resin transformer for power distribution are investigated by FEM program.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.9
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• pp.166-172
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• 2003

Vibration and Noise of air conditioner are entirely determined by compressor vibration. Compressor vibration transmitted to the enclosure of air conditioner or pipes connected compressor with heat exchanger. Enclosure generate(noise and vibration. Therefore, the analysis of compressor vibration analysis is considered significant technical issue. For the reduction of vibration of compressor, it is necessary to grasp correctly vibration transmission paths and excitation sources in the compressor shell. Because, shell ( Surface of compressor ) shows whole vibration characteristic of compressor mechanism. In this paper, vibration intensity was applied to measure vibration energy flow on the shell .From this technique, it is possible to catch the path of vibration propagation along the one cycle and the location of vibration energy sources may change with time on the shell.

• Journal of Magnetics
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• v.9 no.2
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• pp.65-68
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• 2004

Magnetically soft nanomaterials obtained by controlled crystallisation of metallic glasses are the newest group of materials for inductive components. In particular, research is carried out in the field of alloys for high temperature applications. This kind of materials must meet two basic requirements: good magnetic properties and stability of properties and structure. In the present work the magnetic properties and structure of Fe-Co-Hf-Zr-Cu-B (HIDTPERM-type) alloys were investigated, as well as their stability. Differential thermal analysis, (DTA), X-ray diffractometry (XRD), transmission electron microscopy (TEM), magnetometry (VSM) and quasistatic hysteresis loop recording were used to characterise structure and properties of the alloys investigated. Optimisation against properties and their stability was performed, resulting in formulation of chemical composition of the optimum alloy, as well as its heat treatment.

• International Journal of Air-Conditioning and Refrigeration
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• v.9 no.3
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• pp.46-56
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• 2001

The present study concerns the numerical simulation of a supply airflow control in a variable air volume (VAY) system. A stratified thermal model (multi-zone model) is suggested to predict a local thermal response of an air-conditioned space. The effects of various thermal parameters such as the cooling system capacity, the thermal mass of an air-conditioned space, the time delay of thermal effect, and the building envelope heat transmission are investigated. Further, the influence of control parameters such as the supply air temperature, the PI control factor and the thermostat location on a VAV system is quantitatively delineated. The results obtained show that the previous homogeneous lumped thermal model (single zone model) may overestimate the time taken to the set point temperature. It is also found that there exist the appropriate ranges of the control parameters for the optimal airflow control of the VAV system.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.7
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• pp.632-641
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• 2000

The present study concerns the simulation of supply-air control in a variable air volume (VAV) system. A stratified lumped thermal model (multi-zone model) is suggested to predict local thermal response of an air-conditioned space. The effects of various thermal parameters such as the cooling system capacity, the thermal mass of air-conditioned space, the time delay of thermal effect, and the building envelope heat transmission are investigated in detail. Further, the influence of control parameters, PI control factor and the sensor location on a VAV system is quantitatively delineated. The results obtained show that the previous homogeneous lumped thermal model (1-zone model) may predict a significantly different thermal response in the air-conditioned space according to the sensor location.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.694-696
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• 2002

Growth behaviors of carbon nanotubes (CNTs) are studied in terms of catalyst by using scanning electron microscopy and transmission electron microscope (TEM). Catalyst films deposited on various substrates are agglomerated into nano-islands during the heat-up to the growth temperature. In particular, we focus on the direct investigation of the microstructures of the CNTs and the interface of CNTs-catalyst-substrate using cross-sectional TEM. We investigate relationship to the subsequent CNTs growth on each nucleation site. The growth of CNTs depends on the catalyst itself but not the silicide formation between the catalyst and the substrate.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.263-263
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• 2000

Electromagnetic Suspension(EMS) System produces no noise, friction and heat through non-contacting operation Therefore, the applicable device using EMS system has a lot of attraction in case of the high-speed and non-contacting transmission EMS with nonlinear properties requires a precise airgap position control and stable kinematics characteristics under the disturbances, In this study, the nonlinear system was linearized by a Nonlinear Feedback Lineariztion(NFL) method. The NFL method requires that the modelling should be exact, and the state variables should be measured and a rapidly operating controller be necessary on account of a heavy data calculating In the experiments. the ideal control characteristics of the NFL was acquired through simulation at first. then the characteristics of the actual system were compared with those of simulation. In addition, the results by NFL were examined and analysed considering the characteristics of the PID control. The Control by NFL shows much stable control characteristics than the PID control. Whereas, the steady state errors occur for various disturbances. hence a robust control design is remained for a further study.

• Applied Microscopy
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• v.19 no.2
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• pp.17-26
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• 1989

The cells of Campylobacter jejuni treated with physical or chemical disinfection agents were comparatively examined by scanning and transmission electron microscopies for their morphological features and internal ultrastructures. The normal cells of C. jejuni, showed typical spiral rod shapes. The ribosomes, nucleoids, and other cellular constituents were observed to be distributed evenly throughout the cytoplasm. The cells treated with heat or UV-light were changed to spherical or irregular shapes and their cell envelopes were destroyed to form ghost cells by liberating their cytoplasmic components. The cells treated with chlorine or monochloramine were also changed into irregular round shapes. The chlorinated cells showed very rough surface structures with many blob-like protrusions, while the surface of the monochloramine-treated cells appeared to be relatively smooth.