• Journal of Technologic Dentistry
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• v.31 no.2
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• pp.23-30
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• 2009

All-ceramic restorations have gained acceptance among clinicians and patients because of their superior esthetics. Most all-ceramic systems have a 2-layer structure, using a weak veneering ceramic over a strong supporting core. often, failure of all-ceramic restorations occurs when the veneering ceramic fractures, exposing the core material. The purpose of this study was to compare the shear bond strength of heat press ceramic system (Zirpress) to zirconia core with various surface treatments. 10 metal cores and 50 zirconia cores were fabricated and divided into six groups according to surface treatment such as Zirliner application, aluminium oxide blasting, and 9.5% HF etching. Sixty specimens were prepared using Zirpress, veneered 8mm height and 3mm in diameter, over the zirconia cores (n=10). The shear bond strength test was performed in a universal testing machine with a crosshead speed of 1/min. Ultimate shear bond strength data were analyzed with One-way ANOVA and the Scheffe's test (p=.05). Within the limits of this study, the following conclusions were drawn: The mean shear bond strengths (MPa) were: 12.93 for $110{\mu}m$ aluminium oxide blasting/Rexillium III/IPS e.Max Zirpress; 14.92 for $50{\mu}m$ aluminium oxide blasting ${\pm}9.5%$ HF etching/Zirconis core/IPS e.Max Zirpress; 16.37 for $110{\mu}$ aluminium oxide blasting + 9.5% HF etching/Zirconis core/IPS e.Max Zirpress; 12.89 for $200{\mu}$ aluminium oxide blasting + 9.5% HF etching/Zirconis core/IPS e.Max Zirpress; 19.30 for 9.5% HF etching/Zirconis core/IPS e.Max Zirpress; 19.55 for Zirliner/Zirconis core/IPS e.Max Zirpress. The mean shear bond strength for ZNTZH (Zirliner/Zirconis core) and ZNTEH (9.5% HF etching/Zirconis core) were significantly superior to MS110H ($110{\mu}$ aluminium oxide blasting/Rexillium III) and ZS200EH ($200{\mu}$ aluminium oxide blasting + 9.5% HF etching/Zirconis core) (p<0.05).

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.05a
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• pp.250-251
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• 2009

For the fabrication of a multilevel resist (MLR) based on a very thin amorphous carbon (a-C) layer an $Si_{3}N_{4}$ hard-mask layer, the selective etching of the $Si_{3}N_{4}$ layer using physical-vapor-deposited (PVD) a-C mask was investigated in a dual-frequency superimposed capacitively coupled plasma etcher by varying the following process parameters in $CH_{2}F_{2}/H_{2}/Ar$ plasmas : HF/LF powr ratio ($P_{HF}/P_{LF}$), and $CH_{2}F_{2}$ and $H_2$ flow rates. It was found that infinitely high etch selectivities of the $Si_{3}N_{4}$ layers to the PVD a-C on both the blanket and patterned wafers could be obtained for certain gas flow conditions. The $H_2$ and $CH_{2}F_{2}$ flow ratio was found to play a critical role in determining the process window for infinite $Si_{3}N_{4}$/PVDa-C etch selectivity, due to the change in the degree of polymerization. Etching of ArF PR/BARC/$SiO_x$/PVDa-C/$Si_{3}N_{4}$ MLR structure supported the possibility of using a very thin PVD a-C layer as an etch-mask layer for the $Si_{3}N_{4}$ layer.

• Animal Bioscience
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• v.34 no.10
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• pp.1663-1673
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• 2021

Objective: Pork belly is considered as the most commercially important and preferable primal cut by consumers worldwide. Thus, this study was conducted to determine the effects of fat levels on the meat quality characteristics of pork bellies. Methods: Seventy-eight growing-finishing pigs collected from different commercial pig farms were slaughtered and used in the present study. After slaughter 24 h, bellies were fabricated according to the Korean Pork Cutting Specification, and immediately sampled for analysis of their fat content. Based on the fat levels, the bellies were segregated into three different groups: low fat (LF, fat ≤20%, n = 15), medium fat (MF, fat 21% to 30%, n = 30), and high fat (HF, fat ≥31%, n = 33). The bellies were then analyzed for meat quality traits, fatty acids, flavor compounds and eating quality properties. Results: The HF group had lower moisture and cooking loss levels compared to the other groups (p<0.05). The LF group presented higher proportions of polyunsaturated fatty acids compared to the other groups (p<0.05). The LF group showed higher amounts of the Maillard reaction-derived flavor compounds (e.g., 2,5-dimethyl pyrazine, 2-ethyl-3,5-dimethyl, and 4-methylthiazole) associated with meaty and roasty flavors whereas, the HF group showed higher amounts of oleic acid- derived compounds (e.g., nonanal and octanal) associated with the fatty and oily flavors. Interestingly, significantly higher scores for all the eating quality attributes (flavor, juiciness, tenderness, and overall acceptance) were found in the HF group compared to those in the LF or MF group (p<0.05). Conclusion: The high-fat bellies (fat ≥31%) had a better technological quality and eating quality compared to the low-fat bellies (fat ≤20%). Thus, increasing the fat content may improve the technological quality and eating quality traits of pork bellies, however, this increase may also result in more trimmed loss due to excessively deposited body fat.

• Journal of Nutrition and Health
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• v.43 no.3
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• pp.224-232
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• 2010

The prevalence of heart failure (HF) is increasing globally and growing evidence has shown that dietary factors play an important role in preventing and improving prognosis of HF. However, little data on nutrient intake in Korean HF patients which are available to develop dietary guidelines for HF. The aims of this study were to estimate nutrient intake in 78 HF patients and evaluate whether the estimated nutrient intake is appropriate compared to dietary reference intake for Koreans. Data are presented as the ratio of actual intake and estimated average requirement (EAR) for each nutrient. The result showed that the average nutrient intakes including total energy and protein met EAR in total patients. However, the deficiencies in mineral and vitamin intakes were found. Moreover, the proportion of subjects with lower intake than EAR was substantial. The results showed that the proportion of male HF patients with inferior intakes to EAR in calcium, potassium (compared to adequate intake: AI), folate and vitamin $B_{12}$ were 38%, 79%, 38%, and 65%, respectively. Also, the proportion of female HF patients with inferior intakes to EAR in calcium, potassium (compared to AI), folate and vitamin $B_{12}$ were 35%, 88%, 38% and 40%, respectively. In particular, the elderly with HF ($\geq$ 70 yrs, n = 28) showed more serious deficiencies in calcium, potassium (compared to AI), folate and vitamin $B_{12}$. In summary, the intakes of potassium, calcium, folate, and vitamin B12 were not sufficient to meet EAR in HF patients. Furthermore, the proportions of subjects with lower intake than EAR in these nutrients were substantial, raising the possibility that these micronutrients may be involved in the pathogenesis of HF. Practical dietary guideline for HF patients is needed to improve prognosis of HF.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.6
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• pp.449-453
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• 2010

In this paper, the electrical characteristics of Fin-type SONOS(silicon-oxide-nitride-oxide-silicon) flash memory device with different trapping layers are analyzed in depth. Two kinds of trapping layers i.e., silicon nitride($Si_3N_4$) and hafnium oxide($HfO_2$) are applied. Compared to the conventional Fin-type SONOS device using the $Si_3N_4$ trapping layer, the Fin-type SOHOS(silicon-oxide-high-k-oxide-silicon) device using the $HfO_2$ trapping layer shows superior program/erase speed. However, the data retention properties in SOHOS device are worse than the SONOS flash memory device. Degraded data retention in the SOHOS device may be attributed to the tunneling leakage current induced by interface trap states, which are supported by the subthreshold slope and low frequency noise characteristics.

• Journal of Powder Materials
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• v.23 no.5
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• pp.391-396
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• 2016

In this study, ultra-fine soft-magnetic micro-powders are prepared by high-pressure gas atomization of an Fe-based alloy, Fe-Hf-B-Nb-P-C. Spherical powders are successfully obtained by disintegration of the alloy melts under high-pressure He or $N_2$ gas. The mean particle diameter of the obtained powders is $25.7{\mu}m$ and $42.1{\mu}m$ for He and $N_2$ gas, respectively. Their crystallographic structure is confirmed to be amorphous throughout the interior when the particle diameter is less than $45{\mu}m$. The prepared powders show excellent soft magnetic properties with a saturation magnetization of 164.5 emu/g and a coercivity of 9.0 Oe. Finally, a toroidal core is fabricated for measuring the magnetic permeability, and a ${\mu}_r$ of up to 78.5 is obtained. It is strongly believed that soft magnetic powders prepared by gas atomization will be beneficial in the fabrication of high-performance devices, including inductors and motors.

• Journal of Microbiology and Biotechnology
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• v.25 no.10
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• pp.1670-1679
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• 2015

Two hollow fiber membrane biofilm reactors (HF-MBfRs) were operated for autotrophic nitrification and hydrogenotrophic denitrification for over 300 days. Oxygen and hydrogen were supplied through the hollow fiber membrane for nitrification and denitrification, respectively. During the period, the nitrogen was removed with the efficiency of 82-97% for ammonium and 87-97% for nitrate and with the nitrogen removal load of 0.09-0.26 kg NH₄⁺-N/m³/d and 0.10-0.21 kg NO₃^--N/m³/d, depending on hydraulic retention time variation by the two HF-MBfRs for autotrophic nitrification and hydrogenotrophic denitrification, respectively. Biofilms were collected from diverse topological positions in the reactors, each at different nitrogen loading rates, and the microbial communities were analyzed with partial 16S rRNA gene sequences in denaturing gradient gel electrophoresis (DGGE). Detected DGGE band sequences in the reactors were correlated with nitrification or denitrification. The profile of the DGGE bands depended on the NH₄⁺ or NO₃^- loading rate, but it was hard to find a major strain affecting the nitrogen removal efficiency. Nitrospira-related phylum was detected in all biofilm samples from the nitrification reactors. Paracoccus sp. and Aquaspirillum sp., which are an autohydrogenotrophic bacterium and an oligotrophic denitrifier, respectively, were observed in the denitrification reactors. The distribution of microbial communities was relatively stable at different nitrogen loading rates, and DGGE analysis based on 16S rRNA (341f /534r) could successfully detect nitrate-oxidizing and hydrogen-oxidizing bacteria but not ammonium-oxidizing bacteria in the HF-MBfRs.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.279-279
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• 2011

나노 입자를 이용한 비휘발성 메모리 소자의 전기적 특성 향상을 위하여 일함수가 Si 보다 큰 금속, 금속산화물, 금속 실리사이드 나노입자를 이용한 다양한 형태의 메모리 구조가 제안되어져 왔다.[1] 특히 이와 같은 나노 부유 게이트 구조에서 터널 절연막의 구조를 소자의 동작 속도를 결정하는데 이는 터널링 되어 주입되는 전자의 확률에 의존하기 때문이다. 양자 우물에 국한된 전하가 누설되지 않으면서 주입되는 전자의 터널링 확률을 증가시키기 위하여, dielectric constant 와 barrier height를 고려한 다양한 구조의 터널 절연막의 형태가 제안 되었다.[2-3] 특히 낮은 전계에서도 높은 터널링 확률은 메모리 소자의 동작 속도를 향상시킬 수 있다. 본 연구에서는 n형 Si 기판위에 Si3N4 및 HfAlO를 각각 1.5 nm 및 3 nm 로 atomic layer deposition 방법으로 증착하였으며 3~5 nm 지름을 가지는 $TiSi_2$ 및 $WSi_2$ 나노 입자를 형성한 후 컨트롤 절연막인 $SiO_2$를 ultra-high vacuum sputtering을 사용하여 20 nm 두께로 형성 하였다. 마지막으로 $200{\mu}m$ 지름을 가지는 Al 전극을 200 nm 두께로 형성하여 나노 부유 게이트 커패시터를 제작하였다. 제작된 소자는 Agilent E4980A precision LCR meter 및 HP 4156A precision semiconductor parameter analyzer 를 사용하여 전기용량-전압 및 전류-전압 특성분석을 하여 전하저장 특성 및 제작된 소자의 터널링 특성을 확인 하여 본 연구를 통하여 제작된 나노 부유 게이트 커패시터 구조가 메모리 소자응용이 가능함을 확인하였다.

• The Journal of Korean Obstetrics and Gynecology
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• v.25 no.4
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• pp.56-65
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• 2012

Purpose: This study aims to analyze Heart Rate Variability(HRV) in women with fibroadenoma compared with non-fibroadenoma women. Methods: We studied 82 patients visiting Kang-Nam Kyung-Hee Korean Hospital Medical Examination Center from January, 2010 to November, 2011. The subjects were categorized in two groups, fibroadenoma group(n=16) and non-fibroadenoma group (n=66). We investigated the difference of HRV between two groups. Results: The square root of the mean squared difference of successive NNs (RMSSD) in fibroadenoma group is significantly lower than non-fibroadenoma group. LF/HF ratio in fibroadenoma group is significantly higher than non-fibroadenoma group. There was no significant difference in low frequency(LF) and high frequency (HF). However, normalized LF in fibroadenoma group is significantly higher than non-fibroadenoma group. In addition, normalized HF in fibroadenoma group is significantly lower than non-fibroadenoma group. Conclusions: Fibroadenoma group is related to autonomic nerve imbalances that is assumed by psychological problems.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.649-654
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• 2019

Stable haptic interaction with virtual environments is essential not only for the safety of the user but also for improving the immersion of the user. If the coefficient of a virtual spring is increased, the system becomes unstable. Therefore, the coefficient of the virtual spring is limited. The haptic system with the high-frequency zero-order-hold (HF-ZOH) is proposed to enhance the stability margin of a virtual spring. In this paper, the relationship among the sampling period of HF-ZOH, the coefficient of the physical damper, and the maximum stable margin of the virtual spring is analyzed. The lager the coefficient of the physical damper is, the shorter the sampling period of the HF-ZOH is, the larger the stable region of the virtual spring becomes. If the ratio N is larger than 40, the stable region of the proposed method is about three times to eight times that of the previous method, according to the coefficient of the physical damper. Hence the method enables to improve the user's realism in virtual environments.