• 한국산학기술학회논문지
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• 제13권9호
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• pp.4159-4164
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• 2012

본 논문에서는 암호통신을 위한 전압 제어형 카오스 신호 발생회로를 설계하였다. 제안하는 회로는 3개의 MOS 소자로 이루어지는 비선형 함수 블록과 소스 팔로워를 버퍼로 하는 이산형 카오스 신호 발생회로로, 비겹침 2상 클럭으로 구동되며, 2개의 제어전압 단자를 가진다. 제안된 회로는 SPICE 모의실험을 통하여 시간특성, 주파수특성 및 분기도 등의 여러 가지 카오스 다이내믹스가 생성됨을 확인하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.1444-1445
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• 2008

최근 Wireless Local Area Network(WLAN), Wide-band Code Division Multiple Access(WCDMA), CDMA2000, Bluetooth 등 다양한 모바일 통신 시스템에 대한 수요가 증가하고 있다. 이와 같은 모바일 통신 시스템에는 70dB이상의 SFDR(Spurious Free Dynamic Range)을 가진 ADC(Analog-to-Digital Converter)가 사용된다. 본 논문에서는 모바일 통신 시스템을 위한 SFDR 70dBc의 성능을 제공하는 10비트, 100Msps 파이프라인 ADC를 제안한다. 제안한 ADC는 요구되는 해상도 및 속도 사양을 만족시키기 위해 3단 파이프라인 구조를 채택하였으며, 입력단 SHA(Sample and Hold)회로에는 Nyquist 입력에서도 10비트 이상의 정확도로 신호를 샘플링하기 위해 부트스트래핑 기법 기반의 샘플링 스위치를 적용하였다. residue amplifier 회로에는 전력을 줄이기 위해 8배 residue amplifier 대신 3개의 2배 ressidue amplifier를 사용하였다. ADC의 높은 사양을 만족시키기 위해서는 높은 이득을 가지는 op-amp가 필수적이다. 제안한 ADC 는 0.18um CMOS 공정으로 설계되었으며, 100Msps의 동작 속도에서 70dBc 수준의 SFDR과 60dB 수준의 SNDR(Signal to Noise and Distortion Ratio)을 보여준다.

• Journal of Biosystems Engineering
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• 제26권5호
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• pp.461-468
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• 2001

Impact between fruits and other materials is a major cause of product damage in harvesting and handling systems. The oriental pears are more susceptible to bruising than other fruits such as European pears and apples, and are required more careful handling. The interest in the handling of the pears for the processing systems has raised the question of the allowable drop height to which pears can be dropped without causing objectionable damage. Drop tests on pears were conducted using an impact device developed by authors to estimate the allowable drop height without bruising. The impact device was constructed to hold in a selected orientation and to release a fruit by vacuum for dropping on to a force transducer. The drop height was adjustable for zero to 60 cm to achieve the desired distance between the bottom of the fruits and the top of the impact force transducer. The transducer was secured to 150 kg$\sub$f/ concrete block. The transducer signal was sampled every 0.17 ms with a strain gage measurement board in the micro computer where it was digitaly stored for later analysis. The selected sample fruit was Niitaka cultivar of pears which is one of the most promising fruit for export in Korea. The pears were harvested during the 1998 harvest season from an orchard in Daejeon. The sample fruit was selected from two groups which were stored for 3 months and 5 months respectively by the method of current commercial practice. The pears were allowed to stabilize at environmental condition(18$^{\circ}C$, 65% rh) of the experimental room. One hundred fifty six pears were tested from the heights of 5, 7.5. 10 and 12.5 cm while measurement were made of impact peak force, contact time, time to peak force, dwell time, pear diameter and mass. The bioyield strength and modulus of elasticity were measured using UTM immediately after each drop test. The allowable drop height was estimated on the base of bioyield strength of the pears in two ways. One was assumed the peak force during impact test increasing linearly with time, and the other was based on the actual drop test results. The computer program was developed for measuring the impact characteristics of the pears and analyzing the data obtained in the study. The peak force increased while contact times decreased with increasing drop height and contact times of the sample from the hard tissue group. The allowable drop height increased with increasing bioyield strength and contact times, and also varied with Poisson\`s ratio, mass and equilibrium radius of the pears. The allowable drop height calculated by a theoretical method was in the range from 1 to 4 cm, meanwhile, the estimated drop height considering the result of the impact test was in the range from 1 to 6 cm. Since the physical properties of fruits affected significantly the allowable drop height, the physical properties of the fruits should be considered when estimating the allowable drop height.

• 한국근적외분광분석학회:학술대회논문집
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• 한국근적외분광분석학회 2001년도 NIR-2001
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• pp.1530-1530
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• 2001

The objectives of this study were to develop models to predict quality parameters of Korean bee-honeys by visible and NIR spectroscopic technique. Two kinds of bee-honey fronl acacia and polyflower sources were tested in this study. The honeys were harvested in the spring of 2000 and stored in the storage facility at 20$^{\circ}C$ during experiments. Total of 394 samples of honey were analyzed. Reflectance spectra, moisture contents, ash, invert sugar, sucrose, F/G (fructose/glucose) ratio, HMF (hydroxymethyl furfural), and C12/C13 ratio of honeys were measured. The average values for the tested honeys were 19.9% of moisture contents, 0.12% of ash, 68.4% of invert sugar, 5.7% of sucrose, 1.27 of F/G(fructose/glucose) ratio, 14.4 mg/kg of HMF, and -19.1 of C12/C13 ratio. A spectrophotometer, equipped with a single-beam scanning monochromator (NIR Systems, Model 6500, USA) and a horizontal setup module, was used to collect reflectance data from honey. The reflectance spectra were measured in wavelength ranges of 400∼2,498 nm. with 2 nm of interval. Thirty-two repetitive scans were averaged, transformed to log(1/Reflectance), and then were stored in a microcomputer file, forming one spectrum per measurement. A sample cell and reflectance plate were made to hold honey samples constantly. Spectra of honey samples were divided into a calibration set and a validation set. The calibration set was used during model development, and the validation set was used to predict quality parameters from unknown spectra. The PLS(Partial Least Square) models were developed to predict the quality parameters of honeys. The first and the second derivatives of raw spectra were also used to develop the models with proper smoothing gap. The MSC (multiplicative scatter correction) and the SNV & Dtr.(standard normal variate and detranding) preprocessing were applied to all spectra to minimize sample-to-sample light scatter differences. The PLS models showed good relationships between predicted and measured quality parameters of honeys in the wavelength range of 1100∼2200 nm. However, the PLS analysis was not good enough to predict HMF of honeys.

• 대한후두음성언어의학회지
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• 제23권1호
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• pp.33-42
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• 2012

Background and Objectives : Dysarthria refers to speech disorder that causes difficulties in speech communication due to paralysis, muscle weakening, and incoordination of speech muscle mechanism caused by damaged central or peripheral nerve system. Pitch, strength and speed are influenced by dysarthria during detonation due to difficulties in muscle control. As evaluation items, alternate motion rate and diadochokinesis have been commonly used, and articulation is also an important evaluation items. The purpose of this study is to find acoustic characteristics on sound production of dysarthria patients. Materials and Methods : Research subjects have been selected as 20 dysarthria patients and 20 subjects for control group, and voice sample was composed of bilabial, alveolar sound, and velar sound in diadochokinetic rate, while consonant articulation test was composed of bilabial plosive, alveolar plosive, velar plosive. Analysis items were composed of 1) speaking rate, energy, articulation time of diadochokinesis, 2) voice onset time (VOT), total duration (TD), vowel duration (VD), hold of plosives. Results and Conclusions : The number of diadochokinetic rate of dysarthria was smaller than control group. Both control group and dysarthria group was highly presented in the order of /t/>/p/>/k/. Minimum energy range per cycle during diadochokinetic rate of dysarthria group was smaller than control group, and presented statistical significance in /p/, /k/, /ptk/. Maximum energy range was larger than control group, and presented statistical significance in /t/, /ptk/. Articulation time, gap, total articulation time during diadochokinetic rate of dysarthria group was longer than control group and presented statistical significance. The articulation time was presented in both control group and dysarthria group in the order of /k/>/t/>/p/, while Gap was presented in the order of /p/>/t/>/k/ for control group and /p/>/k/>/t/ for dysarthria group. VOT, TD, VD regarding plosives of dysarthria group were longer than control group. Hold showed large deviation compared to control group that had appeared due to declined larynx and articulation organ motility.

• 대한수학교육학회지:학교수학
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• 제19권3호
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• pp.533-551
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• 2017

통계교육 연구자들은 형식적 추리 방법을 지도하기에 앞서 비형식적 추리를 지도할 것을 강조하며 통계적 추리의 발달 과정에 주목하고 있다. 본 연구는 표본 비교하기 과제와 모집단의 그래프 추측하기 과제를 해결하는 과정에서 나타나는 중 고등학생들의 비형식적 통계적 추리의 수준과 각 수준별 특징을 분석하였다. 연구 결과, 표본 비교하기 과제에서는 개인적인 의견에 기초하여 타당하지 않은 추리를 하는 수준, 자료에 대한 국소적 관점을 가진 수준, 자료에 대한 전체적 관점으로 전환되는 수준, 분포의 다각적인 측면에 주목하는 수준, 통계적 개념들을 통합하여 추리하는 수준이 확인되었다. 모집단의 그래프 추측하기 과제에서는 개인적인 의견에 기초하여 타당하지 않은 추리를 하는 수준, 표본대표성에만 주목하고 표집변이성을 고려하지 않는 수준, 표본대표성과 표집변이성을 모두 고려하며 분포의 한 측면에 주목하여 부분적으로 타당한 추리를 하는 수준, 분포의 다각적 측면에 주목하는 수준, 통계적 개념들을 통합하여 추리하는 수준이 확인되었다.

• 간호행정학회지
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• 제19권5호
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• pp.555-564
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• 2013

Purpose: The purpose of this study was to examine nurses' experience of workplace incivility from coworkers, supervisors, patients or patients' families, and doctors. The researcher identified the relationships among empowerment, burnout, and organizational commitment of hospital nurses. Methods: The sample included 415 hospital nurses. Data were collected through questionnaires and analyzed using SPSS and AMOS. Results: The average incivility score was 2.94 from doctors and 2.89 from patients or patients' families, higher than from supervisors (1.90) and coworkers (1.87). The variables affecting burnout included direct effect of empowerment (${\beta}$=-.46, p<.001), direct effect of patients or patients' family incivility (${\beta}$=.14, p<.001), direct effect of supervisor incivility (${\beta}$=.12, p<.001), and direct effect of doctor incivility (${\beta}$=.09, p<.001). The variables affecting organizational commitment were direct effect of burnout (${\beta}$=-.58, p<.001), indirect effect of empowerment (${\beta}$=-.23, p<.001), indirect effect of patients or patients' family incivility (${\beta}$=-.12, p<.001), indirect effect of supervisor incivility (${\beta}$=-.10, p<.001), and indirect effect of doctor incivility (${\beta}$=-.09, p<.001). Conclusion: The results indicate that incivility affecting nurses results in a high degree of burnout and a low degree of organizational commitment. Therefore, it is necessary to assess incivility cases and to hold workshops designed to curb incivility and establish healthy workplaces.

• 천문학회보
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• 제36권2호
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• pp.66.2-66.2
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• 2011

The unexpected rising flux of early-type galaxies at decreasing ultraviolet (UV) wavelengths is a long-standing mystery. One important observational constraint is the correlation between UV-optical colours and Mg2 line strengths found by Burstein et al. (1988). The simplest interpretation of this phenomenon is that the UV strength is related to the Mg line-strength. Under this assumption, we expect galaxies with larger Mg gradients to have larger UV colour gradients. By combining UV imaging from GALEX, optical imaging from MDM and SAURON integral-field spectroscopy, we investigate the spatially-resolved relationships between UV colours and stellar population properties of 34 early-type galaxies from the SAURON survey sample. We find that galaxies with old stellar populations show tight correlations between the FUV colours (FUV-V and FUV-NUV) and the Mg b index, $H{\beta}$ index and metallicity [Z/H]. We have also derived logarithmic internal radial colour, measured line strength and derived stellar population gradients for each galaxy and again found a strong dependence of the FUV-V and FUV-NUV colour gradients on both the Mg b line-strength and the metallicity gradients. In particular, global gradients of Mg b and [Z/H] with respect to the UV colour across galaxies are consistent with their local gradients within galaxies, suggesting that the global correlations also hold locally. From a simple model based on multi-band colour fits of UV upturn and UV-weak galaxies, we have identified a plausible range of parameters that reproduces the observed radial colour profiles. In these models, the centers of elliptical galaxies, where the UV flux is strong, are enhanced in metals by roughly 60% compared to UV-weak regions.

• 대한가정학회지
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• 제39권1호
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• pp.65-80
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• 2001

This study aimed to investigate the changed consciousness and expenditure on Kyong-Jo after IMF economic crisis and the some factors which have effects on the change. The expenditure on Kyong-Jo included donations and gifts associated with congratulations and condolences. The data were collected through the personal questionnaire on Cheju Island. The sample consisted of 400 married adults whose age were between 20 to 65. The independent variables were some individual characteristics, household related variables, and Kyong-Jo related variables. The dependent variables included the change in consciousness and expenditure on Kyong-Jo. The data were analyzed by methods such as frequencies, means, Multiple Regression and Logistic Regression analysis. Major results were as follows. The respondents perceived that Kyong-Jo is fundamentally a good custom to help each other when some one is in the hard time. Their perception of the expenditure on Kyong-Jo has not been changed even since IMF economic crisis. 70% of the respondents staid that there was little difference of the expenditure on Kyong-Jo before and after IMF economic crisis. This trend is in contrast to the perception and the expenditure of the people who lived in the other residences after IMF economic crisis. The factors which had significant effects on the respondent's consciousness of the expenditure on Kyong-Jo were occupation, whether owns a house or not, household income, and household assets. The change of household expenditure on Kyong-Jo was effected by the respondent's sex, occupation, household income, household assets, and social network. These results suggested that the respondents on Cheju Island more strongly hold the conservative perception to the expenditure on Kyong-Jo rather than the people in other residences.

• 아태비즈니스연구
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• 제14권1호
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• pp.73-91
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• 2023

Purpose - The purpose of this study is to re-examine the disclosure effect of stock splits and long-term performance after stock splits using stock split data over the past 10 years, and infer the motivation (signal or opportunism) of stock splits. In addition, we focus on exploring the determinants of the short- and long-term market response to stock splits. Design/methodology/approach - We measure the short-term market response to a stock split and the long-term stock performance after the stock split announcement using the event study method. We analyze whether there is a difference in the long-term and short-term market response to a stock split according to various company characteristics through univariate analysis and regression analysis. Findings - In the case of the entire sample, a statistically significant positive excess return is observed on the stock split announcement date, and the excess return during the 24-month holding period after the stock split do not show a difference from zero. In particular, the difference between short-term and long-term returns on stock splits is larger in companies with a large stock split ratio, small companies, large growth potential, and companies with a combination of financial events after a stock split. Research implications or Originality - The results of this study suggest that at least the signal hypothesis for a stock split does not hold in the Korean stock market. On the other hand, it suggests that there is a possibility that a stock split can be abused by the manager's opportunistic motive, and that this opportunism can be discriminated depending on the size of the stock split, corporate characteristics, and financing plan.