• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.9
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• pp.1941-1948
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• 1997

In this paper, the power efficient linear upconversion mixer which is a functional circuit in transmit path of intermediate frequency(IF) part of Code Division Multiple (CDMA) cellular phone was explained. In generally, the low CMOS devices limits the implementation of upconversion mixer especially for lower loads. Using replica transconductor, the linear range is extended up to the limit. Thiscircuit was imprlemented using $0.8{\mu}\textrm{m}$ N-well CMOS technology with 2-poly/2-metal. The active area of chip is $0.53mm{\times}0.92mm$. The power consumption is 30mW with 3.3V suply voltage. The 1dB conpression characteristics is -27.3dB with $25{\Omega}$. load and being applied by 2-tone input signal. The mixer operates properly above 200MHz.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.8
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• pp.2064-2071
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• 1998

A new digital clock level translator has been designed in order to produce a clock source of the internal logic circuits. The translator output has 50% duty ratio from small sinusoidal input such as TCXO which oscillates itself in poratable components. The circuit consists of positive and negative comparators, RS latch, charge pump, and reference vol- tage generator. It detects pulse width of the output waveform and feedbacks the control signal to the input com-parator. It detects pulse width of the output waveform and feedbacks the control signal to the input com-parator reference, producing output waveform with valid 50% duty ratio of the digital signal level. The designed level translator can be used as a sampling clock source of ADC, PLL and the colck source of the clock synthesizer. The circuit wasdesigned in a 0.8.mu.m analog CMOS technology with double metal, double poly, and BSIM3 circuit simulation model. From our experimental results, a stable operating characteristics of 50 +3% duty ratio was obtained from the sinusoidal input wave of 370 mV.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.5
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• pp.372-378
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• 2009

With the increase in capacity of photovoltaic generation systems, studies are being actively conducted to improve system efficiency. In order to develop the high performance photovoltaic power system it is required to understand the physical characteristics of the solar cell. However, solar cell models have a non-linear form with many parameters entangled and conventional methods suggested to extract the parameters of the solar cell model require some kind of assumptions, which accompanies the calculation errors, thereby lowering the accuracy of the model. Therefore, in this paper a novel method is proposed to calculate the ideality factor and reverse saturation current of the solar cell from the I-V curve measured and announced by solar cell manufacturers, derive the ideal I-V curve, and then extract the series and shunt resistances value from the difference between the ideal and measured I-V curve. Also, validity of the proposed method is demonstrated by calculating the correlation between I-V curve based on modeling parameters and I-V curve actually measured through least squares method.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.11
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• pp.277-280
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• 1996

We have developed a ground-isolation circuit in order to reduce the noise of the internal controller system for the total artificial heart(TAH) and ventricular assist device(VAD). Using the ground-isolation technique, we could transmit the analog target signal to other pheriperal device including IBM PC via RS232C and polygraph, with no noise. Experimental results of VAD showed that there was less impulsive noise in current signal which caused in our previous conventional system. Therefore it could be proved that implementation of isolation technique is very effective to improve the signal to noise ratios of analog signal transmission for TAH or VAD.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.11
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• pp.273-276
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• 1996

In the Total Artificial Heart (TAH) and Ventricular Assist Device (VAD), the size implanting the internal controller into human body is very serious problem. Hence, we need the size reduction of that controller for safe implantation. Using PSD302 chip for microcontroller-based applications, we could decrease the number of components in the digital control board and miniaturize the digital control board. We could replace a ROM, RAM, and a latch with that single chip, so the size of the newly developed board could be half the previous board.

• 한국노년학
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• v.32 no.4
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• pp.1181-1197
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• 2012

This study aims to validate the Attitudes to Aging Questionnaire(AAQ), which was recently developed in foreign countries, for Korean elderly. Using a sample of 320 older individuals living in Seoul, Gyeonggi, Chungcheong areas, statistical analyses including item analysis, exploratory factor analysis, convergent validity analysis were attempted to AAQ which composed of three factors with 24 items. In result, the three factor model of AAQ(including psychosocial loss, physical change, and psychological growth) were reconstructed in which new three factors(psychological loss, social loss, and change and growth in body and mind) were confirmed and three items were deleted. Reliability and convergent validity of AAQ-21 were confirmed. AAQ-21 would be useful to researchers and practitioners working with older adults for systematically assessing the attitudes to aging of older individuals and thus contribute to development of social policies and welfare programs for the elderly.

• The Journal of the Korea Contents Association
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• v.22 no.10
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• pp.497-505
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• 2022

This study was conducted to confirm the effect of noise generated by military training on the life satisfaction of residents living near military facilities. In 2017, an interview survey was conducted on 904 adult residents living near military facilities. The life satisfaction score of the survey subjects was analyzed to be 3.17 out of a total of 5 points, which was confirmed to be lower than that of previous studies on adults. Factors influencing the life satisfaction of residents around military facilities were analyzed. Life satisfaction as dependent variables, demographic factors and physical damage experience factors, and mental damage experience factors were selected as independent variables. As a result of regression analysis, it was analyzed that monthly average household income (coef.=0.09, p<0.001), emotional anxiety (coef.=-0.34, p<0.001), and stress (coef.=-0.05, p<0.001) affected life satisfaction. This study is expected to be used as basic data for establishing policies to improve the life satisfaction of residents living in areas around military facilities.

• Korean Journal of Otorhinolaryngology-Head and Neck Surgery
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• v.55 no.8
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• pp.498-507
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• 2012

Background and Objectives We aimed to develop a Korean version of the velopharyngeal insufficiency (VPI) speech corpus system. Subjects and Method After developing a 3-channel simultaneous speech recording device capable of recording nasal/oral and normal compound speech separately, voice data were collected from VPI patients aged more than 10 years with/without the history of operation or prior speech therapy. This was compared to a control group for which VPI was simulated by using a french-3 nelaton tube inserted via both nostril through nasopharynx and pulling the soft palate anteriorly in varying degrees. The study consisted of three transcriptors: a speech therapist transcribed the voice file into text, a second transcriptor graded speech intelligibility and severity and the third tagged the types and onset times of misarticulation. The database were composed of three main tables regarding (1) speaker's demographics, (2) condition of the recording system and (3) transcripts. All of these were interfaced with the Praat voice analysis program, which enables the user to extract exact transcribed phrases for analysis. Results In the simulated VPI group, the higher the severity of VPI, the higher the nasalance score was obtained. In addition, we could verify the vocal energy that characterizes hypernasality and compensation in nasal/oral and compound sounds spoken by VPI patients as opposed to that characgerizes the normal control group. Conclusion With the Korean version of VPI speech corpus system, patients' common difficulties and speech tendencies in articulation can be objectively evaluated. Comparing these data with those of the normal voice, mispronunciation and dysarticulation of patients with VPI can be corrected.

• The Journal of the Korea Contents Association
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• v.14 no.4
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• pp.243-248
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• 2014

This study has been carried out to find out current status of understanding radiation safety expertise by workers under the present training scheme and to minimize radiation risks at work as well as to refurbish training systems for mitigation of uneasiness of the people at large in near future. Questionnaire survey asking 30 items was carried out during 3 months from May to July, 2013. The number of the overall respondents were about 500. Overall scores of hath degree of the basic knowledge and of the attitude related with radiation safety could he procured through analysis of the questionnaire data. Results were as followings: The workers of the higher academic level, the larger of the accumulated training time and the worker's personal antecedents, the more accredited license holders showed the larger scores of the basic knowledge of radiation as well as the attitude related with the radiation safety. The group having higher basic knowledge also showed the higher score in attitude related with radiation safety. The overall scores obtained from the radiation workers in industrial sector were relatively lower, in general, than those of the other sectors. These results suggest that the training program might better be separately implemented. A specific training program implementation might be desirable particularly for the workers in industrial sectors so as not only to reduce radiation risks of workers but also to mitigate the uneasiness arising among the people at large.

• Korean journal of applied entomology
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• v.56 no.2
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• pp.147-152
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• 2017

Heart contraction is essential for insect hemolymph circulation, in which various physiological changes need control of the heart contraction. Thus, interruption of heartbeats intimidate insect survival. Chlorine dioxide induces release of reactive oxygen species (ROS), which has been regarded as the main insecticidal agent. This study analyzed the effect of chlorine dioxide on heartbeats of the Indianmeal moth, Plodia interpunctella. The larvae have the dorsal vessel on the medial dorsal region in a form of an extending tube from the first thorax to 10th abdominal segment. Dorsal vessel contraction was noticeable between 3rd and 10th abdominal segments, where five heart chambers were observed. Average heartbeat rate was 118.6 beats per min at $25^{\circ}C$. However, the heartbeats varied with ambient temperature. Injection of chlorine dioxide to hemocoel suppressed the heartbeats in a dose-dependent manner. The suppressive effect of chlorine dioxide also increased with exposure time to gas form of the chemical at 100 ppm. However, vitamin E (an antioxidant against ROS) treatment significantly rescued the larvae treated with chlorine dioxide in the heart contraction activity. These results suggest that chlorine dioxide negatively influences on the heart contraction of P. interpunctella via its production of ROS.