• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.11 s.353
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• pp.58-68
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• 2006

This work proposes a 10b 250MS/s $1.8mm^2$ 85mW 0.13um CMOS A/D Converter (ADC) for high-performance integrated systems such as next-generation DTV and WLAN simultaneously requiring low voltage, low power, and small area at high speed. The proposed 3-stage pipeline ADC minimizes chip area and power dissipation at the target resolution and sampling rate. The input SHA maintains 10b resolution with either gate-bootstrapped sampling switches or nominal CMOS sampling switches. The SHA and two MDACs based on a conventional 2-stage amplifier employ optimized trans-conductance ratios of two amplifier stages to achieve the required DC gain, bandwidth, and phase margin. The proposed signal insensitive 3-D fully symmetric capacitor layout reduces the device mismatch of two MDACs. The low-noise on-chip current and voltage references can choose optional off-chip voltage references. The prototype ADC is implemented in a 0.13um 1P8M CMOS process. The measured DNL and INL are within 0.24LSB and 0.35LSB while the ADC shows a maximum SNDR of 54dB and 48dB and a maximum SFDR of 67dB and 61dB at 200MS/s and 250MS/s, respectively. The ADC with an active die area of $1.8mm^2$ consumes 85mW at 250MS/s at a 1.2V supply.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.199-199
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• 2016

Commercially pure titanium (cp-Ti) and Ti alloys (typically Ti-6Al-4V) display excellent corrosion resistance and biocompatibility. Although the chemical composition and topography are considered important, the mechanical properties of the material and the loading conditions in the host have, conventionally. Ti and its alloys are not bioactive. Therefore, they do not chemically bond to the bone, whereas they physically bond with bone tissue. The electrochemical deposition process provides an effective surface for biocompatibility because large surface area can be served to cell proliferation. Electrochemical deposition method is an attractive technique for the deposition of hydroxyapatite (HAp). However, the adhesions of these coatings to the Ti surface needs to be improved for clinical used. Plasma electrolyte oxidation (PEO) enables control in the chemical com position, porous structure, and thickness of the $TiO_2$ layer on Ti surface. In addition, previous studies h ave concluded that the presence of $Ca^{+2}$ and ${PO_4}^{3-}$ ion coating on porous $TiO_2$ surface induced adhesion strength between HAp and Ti surface during electrochemical deposition. Silicon (Si) in particular has been found to be essential for normal bone and cartilage growth and development. Zinc (Zn) plays very important roles in bone formation and immune system regulation, and is also the most abundant trace element in bone. The objective of this work was to study electrochemical characteristcs of Zn and Si coating on Ti-6Al-4V by PEO treatment. The coating process involves two steps: 1) formation of porous $TiO_2$ on Ti-6Al-4V at high potential. A pulsed DC power supply was employed. 2) Electrochemical tests were carried out using potentiodynamic and AC impedance methoeds. The morphology, the chemical composition, and the micro-structure an alysis of the sample were examined using FE-SEM, EDS, and XRD. The enhancements of the HAp forming ability arise from $Si/Zn-TiO_2$ surface, which has formed the reduction of the Si/Zn ions. The promising results successfully demonstrate the immense potential of $Si/Zn-TiO_2$ coatings in dental and biomaterials applications.

• Proceedings of the KAIS Fall Conference
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• 2010.11a
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• pp.115-116
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• 2010

광역상수도의 경우 수자원공사 및 지방상수도 사업자들에 의해 전문적으로 수질을 관리하고 음용수를 보급하고 있으나 소규모 수도시설의 경우 전문능력을 갖춘 관리자가 아닌 마을의 대표자가 맡아 관리함에 따라 안정성 및 유지관리의 어려움이 자주 제기되고 있다.[1] 또한 소규모 수도시설의 경우 취수원으로 지하수나 계곡수를 이용하여 여과나 염소소독을 거쳐 음용수로 이용함에 따라 중금속 및 무기이온 등 각종 오염물질이 효과적으로 제거되지 않아 이를 사용하는 주민들이 불편함을 겪고 있는 실정이다. 환경부의 법정 수질 검사에 따르면 부적합 판정을 받은 곳의 대부분은 마을상수도와 소규모 급수시설인 것으로 나타났으며 초과 항목으로는 무기이온 중 특히 불소와 질산성질소 인 것으로 나타났다.[2] 이러한 문제점을 해결하고자 기존의 고도 정수처리 시설인 막여과, 오존처리, 활성탄 흡착 공정 등을[3-5] 적용하고 있으나 소규모 수도시설에 적용하기에는 유지관리, 규모, 경제적 측면 등 여러 한계점을 지니고 있다. 따라서 본 연구에서는 이러한 문제점을 해결하기 위한 방안으로 전기응집기술을 이용하여 음용수 수질기준을 초과하는 무기이온 중 불소와 질산성 질소를 제거하고자 하였다. 전기응집기술은 제거효율이 높고, 운전이 용이하며 부가적인 화학약품의 첨가가 불필요하다.[6,7] 또한 기존의 고도정수처리 기술에 비해 전기응집 공정은 처리효율과 경제적인 측면 모두를 만족시키고 있어 소규모 수도시설의 불소와 질산성질소를 효과적으로 제거할 수 있는 방안으로 판단된다. 본 연구에 사용된 실험장치는 직류전원공급장치 (DC power supply), 반응조, 전극으로 구성되어 있다. 직류전원공급장치는 최대전압 30 Volt, 최대 전류 30 Amper 까지 조절 가능하였으며 반응조의 크기는 14.5cm(w) ${\times}$ 9cm(L) ${\times}$ 22cm(H) 이고 실용적 1.5L이다. 반응조의 상부에는 전극이 고정될 수 있도록 0.5cm 간격의 홈을 만들어 제작 하였다. 전극은 가용성 전극인 알루미늄 (Al), 스테인레스스틸(SUS304)를 이용하였다. 이를 통해 전류밀도, 전극간격 등의 변수를 두어 최적의 전기응집 운전 조건을 파악하였으며 이는 소규모 수도시설의 수질개선 향상에 도움이 될 수 있을 것으로 판단된다.

• The Journal of Korean Medicine
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• v.27 no.1 s.65
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• pp.165-183
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• 2006

Objectives : We implemented the Artemisia Extract Moxibustion Method and had the clinical tests for the diabetes with it. Methods : We implemented Artemisia extract made by extracting the vasodilator and antioxidant compounds from Artemisia-CH2C12 fraction and the moxibustion method constructed with DC Power supply, controller, Artemisia pad. single and multiple heating terminal with PTC(Positive Temperature Coefficient) thermistor. And we performed to estimate the efficiency on the questionnaire and the clinical tests with 23 cases of the diabetics. Results : We have estimated the improvement over 60% the symptoms that were the upper and lower limbs pain, frequent urination, spontaneous perspiration, thirst, decrease of body weight, and malaise after the moxibustion treatment on 5 cases among 23 cases. And the 19 cases took the biochemical check-up after the moxibustion treatment. From the results of biochemical check-up, the average HbAlc of before treatment was 8.400%, and after treatment 7.632%. The average HbAlc was decreased significantly after treatment (P<0.001). And the average urinary blood of before treatment was 0.73 and after treatment 0.27. The average urinary blood was decreased significantly after treatment (P<0.001). In addition the average FBS before treatment was 182.64 mg/dl, after treatment 161.77 mg/dl. Conclusions : We could estimate that our proposed moxibustion method was a significant treatment method for the diabetes.

• Restorative Dentistry and Endodontics
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• v.25 no.4
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• pp.527-535
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• 2000

The purpose of this study was to evaluate effects of smear layer and dentin primers on the sealing ability of root canals. 126 extracted human teeth with single, straight canals and mature apices were used. The Samples were first classified into six groups as follows: presence of smear layer; absence of smear layer; Scotchbond Bond Multi-Purpose; All Bond 2; Mac Bond 2; Clearfil Liner Bond 2. A Positive control was also established. All teeth except the control group were then obturated with thermoplasticized gutta-percha and AH26. Electrochemical and dye penetration technique were later used to evaluate the degree of micro leakage through the root canal. Seventy teeth were then immersed in a 1% potassium chloride solution and An external power supply(DC 10 V) was then applied to the circuit for the electrochemical microleakage test. The degree of Microleakage was determined over period of 28 days before being evaluated. In total, 48 teeth were submitted to the dye infiltration technique. All specimen were suspended in 2% methylene blue dye for 1 week before being longitudinally split. The degree of dye infiltration was measured under a stereo microscope at ${\times}10$ magnification and evaluated. The results were as follows: 1. Apical microleakage increased throughout the test period in all group and one group having a smear layer showed a dramatic increase under electrochemical test (p<0.05). In the group having smear layer, the degree of apical microleakage was the highest, and the micro leakage was much higher than in the smear layer removed group in electrochemical test (p<0.05). Scotchbond Multi-Purpose, All Bond 2, Mac Bond 2 and Clearfil Liner Bond 2 showed lower micro leakage than one group having smear layer. The All Bond 2 and Clearfil Liner Bond 2 treated groups showed the lowest microleakage in electrochemical test (p<0.05). 2. There was no significant difference between the experimental groups in dye penetration technique. These results suggested that the removal of the smear layer from root canal and concomitantly the application of dentin primer into root canal could improve the sealing ability of root canal obturation.

• Journal of the Korean Ceramic Society
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• v.40 no.10
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• pp.967-972
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• 2003

The inner-diameter 5 cm cold hollow cathode ion source was designed for the high current density and the homogeneous beam profile of ion beam. The ion source consisted of a cylindrical cathode, a generation part of magnetic field, a plasma chamber, convex type ion optic system with two grid electrode, and DC power supply system. The cold hollow cathode ion sources were classified into standard type (I), electron output electrode modified type (II). The operation of the ion source was done with discharge current, ion beam potential and argon gas flow rate. The modification of electron output electrode resulted in uniform plasma generation and uniform area of ion beam was extended from 5 cm to 20 cm. Improved ion source was evaluated with beam uniformity, ion current, team extraction efficiency, and ionization efficiency.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.1
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• pp.39-45
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• 2009

Statement of problem: Recently precalcification treatment has been studied to shorten the period of the implant. Purpose: This study was performed to evaluate the effect of precalcification treatment of $TiO_2$ Nanotube formed on Ti-6Al-4V Alloy. Material and methods: Specimens of $20{\times}10{\times}2\;mm$ in dimensions were polished sequentially from #220 to #1000 SiC paper, ultrasonically washed with acetone and distilled water for 5 min, and dried in an oven at $50^{\circ}C$ for 24 hours. The nanotubular layer was processed by electrochemical anodic oxidation in electrolytes containing 0.5 M $Na_2SO_4$ and 1.0 wt% NaF. Anodization was carried out using a regulated DC power supply (Kwangduck FA, Korea) at a potential of 20 V and current density of $30\;㎃/cm_2$ for 2 hours. Specimens were heat-treated at $600^{\circ}C$ for 2 hours to crystallize the amorphous $TiO_2$ nanotubes, and precalcified by soaking in $Na_2HPO_4$ solution for 24 hours and then in saturated $Ca(OH)_2$ solution for 5 hours. To evaluate the bioactivity of the precalcified $TiO_2$ nanotube layer, hydroxyapatite formation was investigated in a Hanks' balanced salts solution with pH 7.4 at $36.5^{\circ}C$ for 2 weeks. Results: Vertically oriented amorphous $TiO_2$ nanotubes of diameters 48.0 - 65.0 ㎚ were fabricated by anodizing treatment at 20 V for 2 hours in an 0.5 M $Na_2SO_4$ and 1.0 NaF solution. $TiO_2$ nanotubes were composed with strong anatase peak with presence of rutile peak after heat treatment at $600^{\circ}C$. The surface reactivity of $TiO_2$ nanotubes in SBF solution was enhanced by precalcification treatment in 0.5 M $Na_2HPO_4$ solution for 24 hours and then in saturated $Ca(OH)_2$ solution for 5 hours. The immersion in Hank's solution for 2 weeks showed that the intensity of $TiO_2$ rutile peak increased but the surface reactivity decreased by heat treatment at $600^{\circ}C$. Conclusion: This study shows that the precalcified treatment of $TiO_2$ Nanotube formed on Ti-6Al-4V Alloy enhances the surface reactivity.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.3
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• pp.46-55
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• 2016

This work proposes a 13b 100MS/s 45nm CMOS ADC with a high dynamic performance for IF-domain high-speed signal processing systems based on a four-step pipeline architecture to optimize operating specifications. The SHA employs a wideband high-speed sampling network properly to process high-frequency input signals exceeding a sampling frequency. The SHA and MDACs adopt a two-stage amplifier with a gain-boosting technique to obtain the required high DC gain and the wide signal-swing range, while the amplifier and bias circuits use the same unit-size devices repeatedly to minimize device mismatch. Furthermore, a separate analog power supply voltage for on-chip current and voltage references minimizes performance degradation caused by the undesired noise and interference from adjacent functional blocks during high-speed operation. The proposed ADC occupies an active die area of $0.70mm^2$, based on various process-insensitive layout techniques to minimize the physical process imperfection effects. The prototype ADC in a 45nm CMOS demonstrates a measured DNL and INL within 0.77LSB and 1.57LSB, with a maximum SNDR and SFDR of 64.2dB and 78.4dB at 100MS/s, respectively. The ADC is implemented with long-channel devices rather than minimum channel-length devices available in this CMOS technology to process a wide input range of $2.0V_{PP}$ for the required system and to obtain a high dynamic performance at IF-domain input signal bands. The ADC consumes 425.0mW with a single analog voltage of 2.5V and two digital voltages of 2.5V and 1.1V.