• Communications for Statistical Applications and Methods
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• v.25 no.5
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• pp.453-470
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• 2018

We study how to distinguish the parameters of the sparse autoregressive (AR) process from zero using a non-convex penalized estimation. A class of non-convex penalties are considered that include the smoothly clipped absolute deviation and minimax concave penalties as special examples. We prove that the penalized estimators achieve some standard theoretical properties such as weak and strong oracle properties which have been proved in sparse linear regression framework. The results hold when the maximal order of the AR process increases to infinity and the minimal size of true non-zero parameters decreases toward zero as the sample size increases. Further, we construct a practical method to select tuning parameters using generalized information criterion, of which the minimizer asymptotically recovers the best theoretical non-penalized estimator of the sparse AR process. Simulation studies are given to confirm the theoretical results.

• Korean Journal of Occupational Health Nursing
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• v.8 no.2
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• pp.176-192
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• 1999

The purpose of this study is to analysis change of industrial health and safety before and after economic crisis(1997~1998). The data were obtained through mail interview with health supervisor(occupational health nurses) during February, 1999. The final sample was consisted of 127 respondents, 97 are selected in this study. The major findings were as follows: First, the percent of industries whose empl safe supervisors, physicians and industry hygi decreased in number is 79.4%, 3.8%, 50.0 21.5% in each. Second, man receiving over 1.5 million won as an average wage of health supervisor is 27.5% in 1997, but it decreased to 25.3% in 1998. Man receiving under 100~150 million won is 48.4% in 1997, but this percent decreased to 36.3% in 1998 and 13.6% of health supervisor regularly were transformed to contingent worker in 1998. Third, especially, budgets for health and saf work place decreased to 13.8% in 1998 than 19. Fourth, industrial accident case, unre accident case, occupational disease decreased than 1997, but mortality from industrial a increased in 250%. Fifth, according to the health diagnosis report, number of case with evidence of disease increased in liver disease, tuberculosis and so on, and number of case with evidence of occupational disease increased in noise induced hearing loss, pneumoconiosis. organic solvent poisoning and so on. Sixth, this survey shows that health council, health education in duty of health supervisor was conducted passive in 1998 thin 1997, and percent of hold two or more positions is 47.6% in medical insurance, 10.7% in accountant's business 8.3 in secretory. 7.1% in telephone operator awl 22.6% in etc. Seventh, distress of health supervisor after economic crisis is 30.9% in employment instability, 19.8% in hold two or more positions and decrease of budgets. For subjugation of the trouble, the respond of active policy of government occupied most.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.11B
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• pp.1895-1902
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• 2000

이 논문에서는 AD 변화기의 앞에 설치되는 샘플-앤드-홀드 회로의 비선형성을 보상하기 위해 신경 회로망 기법과 볼테라 급수 모델을 직접적으로 적용하는 기법을 제안한다. 제안하는 기법들의 성능을 비교하기 위해, 볼테라 급수 모델에 기반을 둔 전통적인 p차 역산 방식의 결과와 비교 검토한다. 비교 검토를 위해서는 모노-톤과 투-톤 신호를 사용하여 출력의 고조파 및 혼변조 레벨을 살펴보았다. p차 역산 방식이 역 시스템을 구하는 것이라면 제안하는 기법들은 최적화 기법에 바탕을 두고 있다고 할 수 있다. 결과를 보면 어떤 한 방식이 다른 방식보다 성능이 월등하다고 할 수 없는데, 그 이유는 각 방식마다 나름대로의 장단점을 갖고 있기 때문이다. 보상 방식의 선택은 신호의 통계적 성질, 신호 레벨, 비선형성의 정도 등을 고려해야 한다.

• Proceedings of the KIEE Conference
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• 2007.10c
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• pp.132-134
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• 2007

The conventional method used low pass filter for computing resistive leakage current from total leakage current. Therefore, it takes long time for computation. In this paper, a new algorithm is proposed to reduce the computation time. In the theory, the resistive leakage current is computed exactly from the signals during only a half period of power voltage. The suggested method uses integrator and sample-hold circuit and it is confirmed to be able to measure the resistive leakage current from total leakage current by simulation.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1398-1400
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• 2005

A novel data driver for passive matrix organic lightemitting devices (PM-OLEDs) with high gray scale images was designed. The proposed circuit consisted of a main current bias circuit as well as sample & hold circuits in each channel of the data driver to compensate a current offset. These results indicate that a data driver designed by using the current offset compensation technique holds promise for poten tial applications in PM-OLED displays with high gray scale images.

• Proceedings of the IEEK Conference
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• 2000.07b
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• pp.587-590
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• 2000

For high-accuracy signal processing of differential capacitance transducers, an interface circuitry based on a switched-capacitor sample/hold circuit is developed. Driven by nonoverlapping two-phase clocks, the interface produces the output voltage which is proportional to the ratio of difference-to-sum of two capacitors of a differential transducer. Performances of a prototype chip fabricated using 0.6 $\mu\textrm{m}$ n-well CMOS process were measured and compared with those simulated by HSPICE. The measured results indicate that 0.1% resolution is achievable with the proposed interface and the temperature-dependence of the interface is small enough fur practical applications.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.4
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• pp.193-200
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• 2014

In this paper, the prototype of one-channel gamma-ray spectroscope for automatic radiopharmaceutical systhesis system was designed and characterized. The prototype employed CZT (CdZnTe) spear detector for gamma-ray detection and employed analog-type signal processing method. A radioactive sample Co-60 was used for measuring performance of the gamma-ray spectroscope and energy spectrum is gained with bandwidth of 1173keV. The analog board is made up of SF (shaping filter) and PHA (peak and hold amplifier) for shaping CZT output signal appropriately and ADC (analog to digital converter) and FPGA (field programmable gate array) for drawing gamma-ray spectrum by counting the digitalized gamma-ray signal data.

• Journal of International Academy of Physical Therapy Research
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• v.3 no.2
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• pp.413-421
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• 2012

Few studies address the use of manual muscle stretching to improve spinal active range of motion(AROM). There is evidence that' Hold-Relax'(HR) is effective for increasing ROM in the extremities, which leads the researchers to anticipate similar benefits in the spine. The purpose of this study is to investigate the effects of HR(trunk flexors) and active thoracic flexion and extension on thoracic mobility, specifically flexion and extension in healthy individuals. A convenience sample of 30 physical therapy students(22-38 years) were randomly assigned to intervention sequence 'A-B' or 'B-A', with at least 7 days between interventions. Intervention' A' consisted of HR of the ventral trunk musculature while 'B' consisted of thoracic flexion-extension AROM. Thoracic flexion and extension AROM were measured before and after each intervention using the double inclinometer method. Paired t-tests were used to compare AROM pre and post-intervention for both groups, and to test for carry-over and learning effects. There was a statistically significant increase(mean=$3^{\circ}$ ; p=0.006) in thoracic extension following HR of the trunk flexors. There were no significant changes in thoracic flexion following HR, or in flexion or extension following the AROM intervention. No carryover or learning effects were identified. HR may be an effective tool for improving AROM in the thoracic spine in pain free individuals. Further investigation is warranted with symptomatic populations and to define the minimal clinical difference(MCD) for thoracic spine mobility.

• Proceedings of the IEEK Conference
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• 2000.06b
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• pp.201-204
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• 2000

In this paper, an A/D converter is implemented to obtain 8bit resolution at a conversion rate of 10Msample/s. This architecture is proposed using the 2-step architecture for high speed conversion rate. It is consisted of sample/hold circuit, low power comparator, voltage reference circuit and DAC of binary weighted capacitor array. Proposed A/D converter is designed using 0.2$\mu\textrm{m}$ CMOS technology. The SNR is 45.3dB at a sampling rate of 10MHz with 1.95MHz sine input signal. When an 8bit 10Msample/s A/D converter is simulated, the Differential Nonlinearity / Integral Nonlinearity (DNL/ INL) error are ${\pm}$1 / ${\pm}$2 LSB, respectively. The power consumption is 13㎽ at single +2.5V supply voltage.

• Communications for Statistical Applications and Methods
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• v.15 no.5
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• pp.709-717
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• 2008

The difference of two one-sided kernel estimators is usually used to detect the location of the discontinuity points of regression function. The large absolute value of the statistic imply discontinuity of regression function, so we may use the difference of two one-sided kernel estimators as the test statistic for testing null hypothesis of a smooth regression function. The problem is, however, we only know the asymptotic distribution of the test statistic under $H_0$ and we hardly expect the good performance of test if we rely solely on the asymptotic distribution for determining the critical points. In this paper, we show that if we adjust the bias of test statistic properly, the asymptotic rules hold for even small sample size situation.