• Journal of Sensor Science and Technology
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• v.9 no.1
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• pp.70-75
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• 2000

The recycled single crystal silicon wafers have been fabricated into solar cells. It can be a solution for the high cost in materials for solar cells and recycling of materials. So, p-type (100) single crystal silicon wafers with high resistivity of $10-14\;{\Omega}cm$ and the thickness of $650\;{\mu}m$ were used for the fabrication of solar cells. Optimistic conditions of formation of back surface field, surface texturing and anti-reflection coating were studied for getting high efficiency. In addition, thickness variation of solar cell was also studied for increase of efficiency. As a result, the solar cell with efficiency of 10% with a curve fill factor of 0.53 was fabricated with the wafers which have the area of $4\;cm^2$ and thickness of $300\;{\mu}m$. According to above results, recycling possibility of wasted wafers to single crystal silicon solar cells was confirmed.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.42 no.6
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• pp.23-36
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• 2005

PLLs have been widely used for many applications including communication systems. This paper presents a VCO with an improved negative skewed delay scheme and a PLL using this VCO. The proposed VCO and PLL are intended for replacing traditional LC oscillators and PLLs used in communication systems and other applications. The circuit designs of the VCO and PLL are based on 0.18um CMOS technology with 1.8V supply voltage. The proposed VCO employs subfeedback loops using pass-transistors and needs two opposite control voltages for the pass transistors. The subfeedback loops speed up oscillation depending on the control voltages and thus provide a high oscillation frequency. The two voltage controls have opposite frequency gain characteristics and result in low phase-noise. The 7-stage VCO in 0.18um CMOS technology operates from $3.2GHz\~6.3GHz$ with phase noise of about -128.8 dBc/Hz at 1MHz frequency onset. For 1.8V supply voltage, the current consumption is about 3.8mA. The proposed PLL has dual loop-filters for the proposed VCO. The PLL is operated at 5GHz with 1.8V supply voltage. These results indicate that the proposed VCO can be used for radio frequency operations replacing LC oscillators. The circuits have been designed and simulated using 0.18um TSMC library.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.49 no.1
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• pp.12-19
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• 2012

Recently, the market of skin-care device has been steadily growing up. In this paper, we tried to develop a personal compound stimulus device more competitive than existing products. As the compound stimulus, biochemical stimulus of herbal extraction fluid, thermal stimulus of plate-shaped carbon fiber heater, and optical stimulus of near infrared LED were selected. By some evaluation tests, the thermal stimulation part and the optical stimulation part were found to be developed properly. Additionally, the efficacy of the mixed stimulus of thermal and optical stimulation was tested in C2C12 mouse myoblast. Through RT-PCR analysis, it was found that, by the developed compound stimulus, the expression of collagen I mRNA and collagen III mRNA increased by 4.9 and 1.3 times respectively.

• Microbiology and Biotechnology Letters
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• v.47 no.3
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• pp.465-472
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• 2019

Candida albicans is an opportunistic human pathogen that causes infections. Candidiasis is often related to antifungal resistance because the pathogen has the ability to form biofilms. In a previous study, we found that the Salvia miltiorriza ethanol extract demonstrated anticandidal activity by altering membrane permeability and inhibiting the cell wall synthesis in C. albicans. Our results here demonstrate that $78{\mu}g/ml$ of the S. miltiorriza extract significantly diminished the early stage biofilms formed by 10 clinical C. albicans isolates by 51.3%; this was analyzed by 2,3-Bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide salt (XTT) reduction assay. The effect of the S. miltiorrhiza extract on the adhesion of C. albicans cells to polystyrene plates and germ tube formation was examined via microscopic investigation. Although the density of the adhered cells was remarkably reduced up on incubation with $39{\mu}g/ml$ S. miltiorrhiza extract, germ tube formation by C. albicans was rarely affected. Quantitative real-time PCR analysis showed that the S. miltiorrhiza extract downregulated the expression of C. albicans hypha-specific genes, EAP1 by 34.7% (p < 0.001), ALS1 by 45.0% (p < 0.001), ALS3 by 48.1% (p < 0.001), and ECE1 by 21.3% (p = 0.006), respectively. Our data suggest that the S. miltiorrhiza ethanol extract significantly inhibited the early stage of biofilm formation by C. albicans by interfering with cell adhesion, by downregulating EAP1, ALS1 and ALS3, and presumably by modifying the cell wall and membrane structure.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.3
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• pp.1-8
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• 2007

PDiabetic neuropathy is one of the most common diabetes related complications including diabetic nephropathy and retinopahty. In clinical practices, nerve conduction velocity (NCV) has been used as a standard method for diagnosing diabetic neuropathy. However, it applies maximum current of 100mA to nerves causing stress and pain to patients. In this study, as a non-invasive method, $TcpO_2$ was utilized to investigate the difference and relationship between $TcpO_2$ and $SpO_2$ of normal and diabetic neuropathy subjects. In addition, a new method of diagnosing diabetic neuropathy using $TcpO_2$ is suggested. 50 normal subjects and 50 diabetic patients with neuropathy diagnosed by NCV participated in this study. Parameters used in this study were $TcpO_2$, $TcpCO_2$, and $SpO_2$. As a result of the $TcpO_2$ measurements, statistical significances were found from $TcpO_2$ of hands and feet from normal and patients group(p<0.01). $SpO_2$ measured from index finger of normal and patient groups showed no statistical significance(p>0.05). On the other hand, $SpO_2$ measured from great toes of normal and patient groups showed statistical significance(p<0.01). Correlation coefficient between $SpO_2$ of finger and $TcpO_2$ of hand was 0.400 (p<0.01) and $SpO_2$ of toe and $TcpO_2$ of foot was 0.471(p<0.01). Both correlation values were statistically significant. Sensitivities and specificities of the $TcpO_2$ method were found to be 66 % and 92 %, respectively. If the suggested $TcpO_2$ method is used periodically, prevention and early diagnosis of diabetic neuropathy would be possible.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.40 no.3
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• pp.163-171
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• 2003

To evaluate the performance of the digital radiography(DR) system developed in our group, the modulation transfer function(MTF) was measured and compared with that of an analog X- ray detector, film/screen system. The DR system has an amorphous selenium(a-Se) layer vacuum-evaporated on a TFT flat panel detector. The speed class 400 film/screen (Fuji) system has been being used in the clinical field as analog X-ray detectors. Both the square wave and slit method were used to evaluate their MTF. The square method was applied to both film/screen and the DR system. The slit method, however, was applied to only DR system. The full-width half maximum resolution of film/screen was 357${\mu}{\textrm}{m}$(1.4 lp/mm at 50% spatial frequency), and the resolution of DR was limited to 200${\mu}{\textrm}{m}$(2.5 lp/mm at 30%). These results indicate the measured resolution limitations approximate to the pixel pitch, 139 ${\mu}{\textrm}{m}$ of TFT. The MTF of DR is higher than that of film/screen by the factor of 1.785. It is proved that our a-Se based DR system has potential usefulness in the clinical field.

• International Commerce and Information Review
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• v.18 no.4
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• pp.55-78
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• 2016

In this study, service quality attributes of uTradeHub were classified based on the Kano model, and quality attributes that should be managed in priority to improve the service quality of uTradeHub were investigated using Timko's customer satisfaction coefficient(CSC) and average satisfaction coefficient(ASC). The results of the study are summarized as follows. First, as a result of classifying service quality attributes based on Kano model, 12 one dimensional qualities, 5 must-be qualities, 2 indifferent qualities were deducted, and many quality attributes of uTradeHub service were confirmed to be one dimensional quality to which is needed to be paid attention and paid more detailed attention to enhance service quality. Second, in the analysis result using Timko's customer satisfaction coefficient, "post processing for problems and complaints", "cost reduction", "efficiency of business processing" were ranked in the top of satisfaction coefficient, and they found to be quality attributes that customer satisfaction increases when service quality was satisfied. While, "post processing for problems and complaints", "interaction", "ability to respond promptly when problems occur" were ranked in the top of unsatisfaction coefficient, and they were analysed to be quality attributes that customer complaints increase when service quality was unsatisfied. Third, in the result of analyzing the quality attributes that should be managed in priority to improve the service quality of uTradeHub based on the average satisfaction coefficient(ASC), "post processing for problems and complaints", "cost reduction", "useful information" were ranked in the top 3, and they were classified as quality attributes that the satisfaction level increases more when they are improved than now, but the satisfaction level decreases when they are worsen.

• Journal of Oriental Neuropsychiatry
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• v.20 no.3
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• pp.189-203
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• 2009

Objectives : This study was to analyze characteristics of MMPI profile, personality and defensive mechanism on 32 Hwa-byeng patients. Methods : 32 Hwa-byeng patients and 28 normal control group were administered the MMPI. The characteristics of MMPI profile and the clinical scales of personality and defensive mechanism were analyzed statistically. Results : 1. Half of female Hwa-byeng patients are in their forties, twelve patients are high school graduates, housewives seem to have Hwa-byeng more than workers, and married ones have Hwa-byeng more than singles, divorcees or separated one 2. 60.6% patients are getting stressed from their husbands(the specific reasons are infidelity(55%), incapability(25%) and violence(20%)). And the rest are from in-law(28.8%), children(6.4%) and their own parents(3.2%). 3. MMPI profile of Hwa-byeng patients appeared as a type of 3-1 elevated by the scale of 3(Hy) and 1 (Hs). And Hwa-byeng patients appeared significantly high in the rest of scales except L, K, Mf and Ma scales comparing to control group. 4. Hwa-byeng patients were classified into 3 groups. First group is "V" type which is high in K scale and low in 3 (Hy), 4(Pd), 6(Pa). Second group is "V" type which is high in K scale and high in 3(Hy), 4(Pd), 6(Pa). Third group is high in F scale and high in 1(Hs), Z(D), 3(Hy), 4(Pd), 6(Pa), 7(Pt), 8(Sc) and 0(Si). 5. The analysis on MMPI profiles indicates that the thirties are highier in F scale than the fifties, the fifties are highier in Hy scale than the forties, workers are highier in Pd scale than housewives, singles or divorcees are highier in Pa scale than the married. 6. The characteristics of personality in Hwa-byeng patients are as follows. They are significantly lower in HST, NAR and very higher in CPS, PAG, DEP, STY, AVD, SZD comparing to control group. Especially in AVD and SZD scales are appeared the highest.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.43 no.3 s.309
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• pp.78-84
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• 2006

Our study aimed at quantitative assessment of a cleft palate nose deformity condition by analyzing the following parameters gathered from a photographic image of a cleft palate patient: (1) angle difference between two nostril axes, (2) center of the nostril and distance between two centers, (3) overlapped area of two nostrils, and (4) the overlapped area ratio of the two nostrils. A regression equation of doctor's grades was obtained using the eight parameters. Three plastic surgeons gave us the glades for the each photographic image by to increments with maximum grade of 100. The average reproducibility of the grades given by the three plastic surgeons and the three laymen using the developed program was $10.8{\pm}4.6%\;and\;7.4{\pm}1.8%$, respectively. Kappa values representing the degree of consensus of the plastic surgeons and the three laymen were 0.43 and 0.83, respectively. Correlation coefficient of the grades evaluated by the surgeons and obtained by the regression equation was 0.642 and that of the grades by the surgeons and by the neural network was 0.798. In conclusion, the developed neural network model provided us better reproducibility, much better consensus, and better correlation than doctor's subjective evaluation in addition to objectiveness and easy application.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.43 no.3 s.309
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• pp.60-66
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• 2006

The purpose of this study was to suggest a new detection method for early diagnosing diabetic neuropathic foot by obtaining a ratio of toe to finger blood flow using photoplethysmography(PPG) and Laser Doppler(LD). Nerve conduction velocity (NCV) has been routinely used for diagnosing neuropathic foot, but it applies strong electric stimulus to peripheries resulting in stress and pain. The blood flow ratio of 50 neuropathic diabetes($0.96{\pm}0.20$) was significantly higher than that of 64 normal person($0.46{\pm}0.15$)(p<0.000). It also showed that toe temperature of neuropathic diabetes($30.5{\pm}1.4^{\circ}C$) was significantly higher than that of normal group($29.3{\pm}2.0^{\circ}C$)(p<0.000). The optimal boundary value of the blood flow ratio was found to be 0.678 and the sensitivity and specificity of this proposed method resulted in 95.3% and 95.3% respectively. Lastly, there were no neuropathic diabetes whose temperature difference between finger and toe was higher than $4.5\;^{\circ}C$.