• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.28 no.3
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• pp.188-195
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• 2002

The purpose of this investigation was to evaluate the relationship between the hydration time of demineralized freeze-dried bone (DFDB) and early new bone formation in rat calvarial defects filled with DFDB. Rats (n = 43) were divided into 4 experimental groups. Standard, transosseous circular defects of the calvaria were made midparietally. In experimental group 1, the defect was grafted immediately after soaking the DFDB. In experimental group 2, the defects were grafted with DFDB after soaking the DFDB for 10 minutes. In experimental groups 3 and 4, the defects were filled after soaking the DFDB for 30 and 60 minutes, respectively. Graft sites were analyzed histologically after healing periods of 1, 2, or 4 weeks. Each group showed similar bone regeneration at each time point by histological analysis. The results of this study were as follows: 1. After 1 week, a significant amount of inflammation, granulation tissue, and edema were found. A small amount of bone was seen, but the amount of bone did not differ between groups. 2. After 2 weeks, a small amount of new bone formation and DFDB resorption were observed. 3. After 4 weeks, a greater amount of new bone formation was observed. The greatest amount of bone formation occurred in experimental group 4 after 4 weeks. We conclude that the hydration time of DFDB does not affect new bone formation and that it is very important to control inflammation in bone grafting.

• The Journal of Advanced Prosthodontics
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• v.6 no.6
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• pp.539-546
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• 2014

PURPOSE. Silk fibroin (SF) is a new degradable barrier membrane for guided bone regeneration (GBR) that can reduce the risk of pathogen transmission and the high costs associated with the use of collagen membranes. This study compared the efficacy of SF membranes on GBR with collagen membranes (Bio-$Gide^{(R)}$) using a rat calvarial defect model. MATERIALS AND METHODS. Thirty-six male Sprague Dawley rats with two 5 mm-sized circular defects in the calvarial bone were prepared (n=72). The study groups were divided into a control group (no membrane) and two experimental groups (SF membrane and Bio-$Gide^{(R)}$). Each group of 24 samples was subdivided at 2, 4, and 8 weeks after implantation. New bone formation was evaluated using microcomputerized tomography and histological examination. RESULTS. Bone regeneration was observed in the SF and Bio-$Gide^{(R)}$-treated groups to a greater extent than in the control group (mean volume of new bone was $5.49{\pm}1.48mm^3$ at 8 weeks). There were different patterns of bone regeneration between the SF membrane and the Bio-$Gide^{(R)}$ samples. However, the absolute volume of new bone in the SF membrane-treated group was not significantly different from that in the collagen membrane-treated group at 8 weeks ($8.75{\pm}0.80$ vs. $8.47{\pm}0.75mm^3$, respectively, P=.592). CONCLUSION. SF membranes successfully enhanced comparable volumes of bone regeneration in calvarial bone defects compared with collagen membranes. Considering the lower cost and lesser risk of infectious transmission from animal tissue, SF membranes are a viable alternative to collagen membranes for GBR.

• Journal of the Korean Home Economics Association
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• v.20 no.2
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• pp.91-102
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• 1982

This study was designed to find out the nutritional defect of general Korean diet and the effective way of nutritional supplementation. Seventy weanling Sprague-Dawley male rats weighing 51.8$\pm$0.9g were blocked into ten groups and fed ten different diets ad libitum for eight weeks: Standard groups(st gp) was given 72% sugar-20% casein diet: Cereal-vegetable group(c-v gp) was fed cereal-vegetable diet(c-v diet) composed of rice, barley, soybean, spinach and cabbage: the other eight groups were fed c-v diets supplemented with casein, vitamin $B_{2}$, calcium, vitamin A, vitamin B2 and A, vitamin A and calcium, vitamin $B_{2}$ and calcium, vitamin A and $B_{2}$and calcium, respectively, on the basis of each nutrients content of standard diet. The results were as follows: 1. Food intakes and body weight gains in all the experimental groups were significantly lower than st gp. Among experimental groups, casein gp and vit B2 gp tended to gain more body weights than c-v gp. 2. Through all the experimental period, F.E.R., pp.E.R., and NDPcal% did nod show significant differences among all the experimental groups and st gp. 3. The weights of liver, kidney, and gastrocnemius were significantly lower in all the experimental groups as compared with st gp. But brain and sex organ weights did not show differences among all the groups. 4. Nitrogen contents of total carcass, liver, and gastrocnemius in all the experimental groups tended to be increased as compared with st gp, and among experimental groups, they tended to be increased by casein supplementation and decreased by ca supplementation. 5. Apparent nitrogen digestibility, urinary and fecal nitrogen excretion, the amount of nitrogen retained, and N.P.U. did not show any significant differences among all the groups. 6. Serum total protein concentrations did not show any significant differences among all the groups.

• The Journal of Korean Medicine
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• v.36 no.1
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• pp.75-85
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• 2015

Objectives: Type 2 diabetes mellitus is a metabolic disease characterized by insulin resistance and high blood glucose level from progressive insulin secretory defect. The rhizome of Atractylodes japonica Koidz. (AJ) has been used for treatment of retention of water in oriental medicine. The aim of this study is to examine the effects of AJ on type 2 diabetes rats. Methods: Type 2 diabetes was induced by 60% high fat diet and low dose streptozotocin. Rats were divided into 4 groups (n = 6); Nor (normal control group), Con (diabetic group treated with vehicle), Met (diabetic group treated with 200 mg/kg metformin) and AJ (diabetic group treated with 100 mg/kg AJ). The body weights and food intakes were measured during the treatment period. After 4 weeks treatment, blood glucose level, HOMA-IR, and protein expressions of IRS-1, p-IRS-1, PPAR-${\gamma}$, and GLUT4 were measured, and histopathological examination of beta cell was performed. Results: Compared with the control group, blood glucose level and HOMA-IR were reduced in rats treated with AJ. Impaired beta cells in pancreas of rats were recovered and phosphorylation of IRS-1 was increased in rats treated with AJ. And also, protein expressions of PPAR-${\gamma}$ and GLUT4 were increased by treatment of AJ. Conclusions: The results suggest that Atractylodes japonica Koidz. may have anti-diabetic effect on type 2 diabetic rats through regulation of blood glucose level and insulin resistance. Therefore Atractylodes japonica Koidz. may have positive effects on patients with type 2 diabetes.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.4 no.1
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• pp.29-34
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• 2010

The fully implantable hearing devices (FIHDs) have been studied to compensate the defect of conventional hearing aids. Typically, a microphone for FIHDs was implanted under the skin of the temporal bone. So, implantable microphone characteristics can be affected by the eating food, chattering teeth and moving artifact. In this paper, we fabricated the physical model that was similar to characteristics of human temporal bone and skin, and we measured implanted microphone sensitivity for effect of bone conducted noise signal. For the measurement of microphone sensitivity, we applied 1 kHz pure sounds that were transmitted to implanted microphone and sine wave vibrations of varied frequency were simultaneously transmitted through the artificial bone. As a result, sensitivity of implanted microphone can be modified by bone conducted signal and this phenomenon was confirmed at varied frequency band.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1867-1869
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• 2003

In this paper, chamber(Circuit breaker compartment of C-GIS) made of stainless steel with 4 mm width is used. Artificial defect was made on enclosure or HV conductor of chamber and $SF_6$ gas was injected into it according to pressure. In this experiment, Acoustic emission sensors of different types was used to compare sensitivity to detect acoustic signal occurred by Partial discharge(PD) of according to types and resonance frequency in $SF_6$ gas atmosphere. Sensors used in tests was R6I, R15I and 2/4/6 Pre-Amplifier connected with R6IU without pre. amp. In case of R6IU, gain was adjusted with 40 dB like other sensors and operated by differential mode. Post amplifier(post. amp) and band pass filter(BPF) were developed Gain of post. amp. is 60 dB and BPF has band width of $50{\sim}300$ kHz. Also, envelope circuit developed reduces frequency of AE sensor. As a result, in $SF_6$ atmosphere, R6IU and R6I had resonance frequency of 60 Hz was better than R15I. Also, R6IU was better than R6I because of type property of pre.amp. had differential mode.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.6
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• pp.490-494
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• 2020

Sulphur hexafluoride (SF₆) is mostly used as a current-insulating medium in gas-insulated switchgears (GIS), owing to its excellent dielectric strength and arc-extinguishing performance. The global warming potential (GWP) of SF₆, however, is 23,900 times that of CO₂, and its life time in the atmosphere is 3,200 years. For these reasons, new eco-friendly gases to replace SF₆ are required. In this study, the partial discharge (PD) characteristics of green gas for grid (g³) and dry air (N₂/O₂) were analyzed to compare with those of SF₆. A PD electrode system was designed to simulate the protrusion defect in GISs and fabricated for experimentation. To compare the PD characteristics of each gas, the discharge inception voltage (DIV), discharge extinction voltage (DEV), discharge magnitude, discharge pulse number, and phase pattern were analyzed. Results from this study are expected to provide fundamental materials for the design of eco-friendly GISs.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.287-290
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• 2005

Once hot forgings for automotive parts such as wheel bearing flange to which cyclic asymmetric bending stress is continuously applied are produced, it is necessary to control their microstructure to obtain superior mechanical properties. It is however hard to control the microstructure uniformly because the strength is reduced as coarsening of ferrite grains. To investigate the microstructural alteration according to process variables during hot working, the variation of the ferrite grain size was studied by utilizing of the computer aided servo-hydraulic Gleeble tester which is hot deformation behavior reproduction equipment. In addition, the effect of the ferrite grain size of raw material on the austenite grain behavior of hot forgings was also examined. The rolling contact fatigue resistance of the induction hardened SAE 1055 steel was compared with the occasion of the same condition of SAE52100 bearing steel. As a result, it was confirmed that the ferrite grain sizes of the forgings depend on the heating temperature and cooling start temperature during hot forging and cooling processes. The induction hardened SAE1055 steel showed a superior rolling contact fatigue resistance to the induction hardened SAE52100 steel. The reason is that SAE1055 steel is freer from the material defect such as segregation than the comparative steel.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.229.2-229.2
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• 2013

Yttrium oxide (Y2O3)는 band gap이 5.5 eV 정도로 상대적으로 넓고, 굴절상수가 1.8, 유전율이 10~15, Silicon 과의 격자 불일치가 작은 특성을 가지고 있다. 또한 녹는점이 높아 열적으로 안정하기 때문에 전자소자 및 광학소자에 다양하게 응용되는 물질이다. Y2O3 박막은 다양한 방법으로 증착할 수 있는데, 그 방법에는 e-beam evaporation, laser ablation, sputtering, thermal oxidation, metal-organic chemical vapor deposition, and atomic layer deposition (ALD) 등이 있다. ALD는 기판 표면에 흡착된 원자들의 자기 제한적 반응에 의하여 박막이 증착되기 때문에 박막 두께조절이 용이하고 step coverage와 uniformity 측면에서 큰 장점이 있다. 이전에는 Y(thd)3 and Y(CH3Cp)3 와 같은 금속 전구체를 이용하여 ALD를 진행하여, 증착 속도가 낮고 defect이 많아 non-stoichiometric한 조성의 박막이 증착되는 문제점이 있었다. 이번 연구에서는, (iPrCp)2Y(iPr-amd)와 탈이온수를 사용하여 Y2O3 박막을 증착하였다. Y2O3 박막 증착에 사용한 Y 전구체는 상온에서 액체이고 $192^{\circ}C$ 에서 1 Torr의 높은 증기압을 갖는다. Y2O3 박막 증착을 위하여 Y 전구체는 $150^{\circ}C$ 로 가열하여 N2 gas를 이용하여 bubbling 방식으로 공정 챔버 내로 공급하였다. Y2O3 박막의 ALD window는 $250{\sim}350^{\circ}C$ 였으며, Y 전구체의 공급시간이 5초에 다다르자 더 이상 증착 두께가 증가하지 않는 자기 제한적 반응을 확인할 수 있었다. 그리고 증착된 Y2O3 박막의 특성 분석을 위해 Atomic force microscopy (AFM)과 X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) 를 진행하였다. 박막의 Surface morphology 는 매끄럽고 uniform 하였으며, 특히 고체 금속 전구체를 사용했을 때와 비교하여 수산화물이 거의 없는 박막을 얻을 수 있었다. 그리고 조성 분석을 통해 증착된 Y2O3 박막이 stoichiometric하다는 것을 알수 있었다. 또한 metal-insulator-metal (MIM) 구조 (Ru/Y2O3/Ru) 의 resistor 소자를 형성하여 저항 스위칭 특성을 확인하였다.

• Korean Journal of Materials Research
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• v.18 no.2
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• pp.84-91
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• 2008

The effects of the deposition and annealing temperature on the structural, electrical and optical properties of Ag doped ZnO (ZnO : Ag) thin films were investigated. All of the films were deposited with a 2wt% $Ag_2O-doped$ ZnO target using an e-beam evaporator. The substrate temperature varied from room temperature (RT) to $250^{\circ}C$. An undoped ZnO thin film was also fabricated at $150^{\circ}C$ as a reference. The as-grown films were annealed in temperatures ranging from 350 to $650^{\circ}C$ for 5 h in air. The Ag content in the film decreased as the deposition and the post-annealing temperature increased due to the evaporation of the Ag in the film. During the annealing process, grain growth occurred, as confirmed from XRD and SEM results. The as-grown film deposited at RT showed n-type conduction; however, the films deposited at higher temperatures showed p-type conduction. The films fabricated at $150^{\circ}C$ revealed the highest hole concentration of $3.98{\times}1019\;cm^{-3}$ and a resistivity of $0.347\;{\Omega}{\cdot}cm$. The RT PL spectra of the as-grown ZnO : Ag films exhibited very weak emission intensity compared to undoped ZnO; moreover, the emission intensities became stronger as the annealing temperature increased with two main emission bands of near band-edge UV and defect-related green luminescence exhibited. The film deposited at $150^{\circ}C$ and annealed at $350^{\circ}C$ exhibited the lowest value of $I_{vis}/I_{uv}$ of 0.05.