• 한국지구과학회지
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• 제37권7호
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• pp.389-397
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• 2016

${\delta}$ Scuti형 변광성 BO Lyn의 파장에 따른 광도곡선 차이를 알아보기 위해서 보현산천문대의 1.8m 반사망원경과 적외선 검출기 KASINICS를 이용한 측광 관측을 수행하였다. 2011년 3월 26일부터 4월 1일까지 총 7일간의 관측 자료로 J, H, Ks필터 광도곡선을 얻어 기존에 보고된 V필터에서의 광도곡선과 비교하여 주기, 극대점, 진폭, 형태에 대한 차이를 알아보았다. 적외선 광도곡선의 주기 분석 결과 단일 주파수해 $f_1=10.712cycle/day$, 주기$P=0.09335{\pm}0.00002days$의 값을 얻었으며, 파장에 따른 주기의 차이는 나타나지 않았다. 적외선에서는 $2f_1$에 해당하는 주파수가 검출되었는데, 이는 고진폭 ${\delta}$ Scuti형 변광성의 특징인 비대칭적인 광도곡선의 형태를 잘 설명해준다. 극대점의 위치를 비교한 결과 계산된 V필터의 예상 극대점보다 관측된 적외선 극대점이 전체 주기의 약 0.3에 해당하는 만큼 더 늦게 나타났다. 진폭은 ${\Delta}J/{\Delta}V=0.328$, ${\Delta}H/{\Delta}V=0.216$, ${\Delta}Ks/{\Delta}V=0.211$로 파장이 길어질수록 변광의 폭이 더 작게 나타났다. 파장에 따른 극대점의 지연과 변광폭의 차이는 맥동변광성의 밝기 변화가 주로 온도변화에 기인하기 때문인 것으로 여겨진다.

• Annals of Clinical Neurophysiology
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• 제1권2호
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• pp.118-125
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• 1999

Background and Aims : Nerve conduction study is invaluable in clinical neurology, especially for assessing peripheral neuropathies. Abnormal nerve conduction studies may result not only from peripheral nerve dysfunction itself, but also from other various mechanical, technical, and physiological factors such as age, sex, height and temperature. So we conducted this study to establish the our own normal values. Methods : In this study, from March. 1997 to July. 1998, 40 Korean adults among person came to Health Promotion Center over the age of 20 without any suspicion of neurological deficits were analysed to determine the effect of compound effects of several physiological factors. Results : The nerve conduction velocities of the upper extremity and proximal segments were faster than those of the lower extremity and distal segments. Physiological factors such as age, height and temperature affect the results of nerve conduction studies in multiple regression analysis. The sex difference is recognized over peroneal motor nerve. There are no sex differences in amplitude transformed into normal distribution. The significant physiological factor affecting the amplitude of nerve conduction is age, whereas height and temperature play no role. Conclusions : In multiple regression analysis, height is widespread variable for the nerve conduction velocities and temperature is important variable for lower extremities. The parametric statistical analysis cannot be applied to the amplitude of the compound muscle or nerve action potentials because of marked left shift in distribution. Sqareroot transformation of the CMAP and CNAP may be useful in normalizing the distribution. The most significant physiological factor affection the amplitude is age. Sex differences are not seen in nerve conduction study.

• 한국지반신소재학회논문집
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• 제14권3호
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• pp.1-12
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• 2015

국내외에서 차수벽이나 흙막이 벽체로 많이 사용되고 있는 강널말뚝의 관입시 일반적으로 진동해머를 이용하여 시공하고 있다. 진동해머 중에서도 유압식 진동해머가 많이 사용되고 있는데, 진동해머의 시동을 켜고 끌 경우 진동해머 편심축의 이동에 따라 고유진동수의 변화로 진동해머에서 공진이 일어나 진동 및 소음이 크게 발생하는 문제점이 있다. 이에 본 연구에서는 일반 유압식 진동해머에서 발생하는 공진 발생에 의한 진동 및 소음을 줄이기 위하여 진폭가변형 유압진동해머를 개발하였다. 개발된 진폭가변형 유압진동해머는 두 쌍의 편심체 수평 각도를 조절하여 진동수 및 진폭을 조절할 수 있으며, 일반 유압식 진동해머와 개발된 진폭가변형 유압진동해머의 기진체 현장실험을 이용한 성능 평가 비교를 통해, 기존 일반 유압식 진동해머에 비해 진폭가변형 유압진동해머의 진동 및 소음이 감소함을 확인하였다. 또한 현장실험 결과 진폭가변형 유압진동해머는 굴삭기의 추력으로 인해 기존 전기식 진동해머에 비해 관입속도가 증가하였으며, 일반 유압식 진동해머에 비해서도 진폭가변으로 지반조건에 따라 관입속도가 빨라질 수 있음을 확인하였다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2001년도 춘계종합학술대회
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• pp.489-492
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• 2001

본 논문에서는 효율적인 홀로그래픽 데이타 저장을 위해, 세기변조를 통한 2차원 이진데이타를 표현함에 있어서 가변적이고 이산적인 랜덤 위상마스크를 함께 사용하는 방법을 연구했다. 가변 위상 마스크는 twisted nematic LCD를 사용해 구현했다.

• 천문학회지
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• 제42권6호
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• pp.155-159
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• 2009

In order to determine color excess in the $uvby\beta$ color system for high amplitude $\delta$ Scuti stars, reddening free $[m_1]$, $[c_1]$, and $\beta$ indices data were obtained from the existing literature for 21 stars. Then, the three intrinsic relations of $(b-y)_0$ - $[m_1]$, $(b-y)_0$ - $[c_1]$, and $(b-y)_0$ - $\beta$ were investigated. Among these, it was shown that the $(b-y)_0$-$[c_1]$ relation is the most useful. By establishing intrinsic $(b-y)_0$-$[c_1]$ relations for six reddening calibration stars, color excesses of other stars were determined.

• Communications for Statistical Applications and Methods
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• 제20권4호
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• pp.271-281
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• 2013

This paper considers a problem of classification of variable stars based on functional data analysis. For a better understanding of galaxy structure and stellar evolution, various approaches for classification of variable stars have been studied. Several features that explain the characteristics of variable stars (such as color index, amplitude, period, and Fourier coefficients) were usually used to classify variable stars. Excluding other factors but focusing only on the curve shapes of variable stars, Deb and Singh (2009) proposed a classification procedure using multivariate principal component analysis. However, this approach is limited to accommodate some features of the light curve data that are unequally spaced in the phase domain and have some functional properties. In this paper, we propose a light curve estimation method that is suitable for functional data analysis, and provide a classification procedure for variable stars that combined the features of a light curve with existing functional data analysis methods. To evaluate its practical applicability, we apply the proposed classification procedure to the data sets of variable stars from the project STellar Astrophysics and Research on Exoplanets (STARE).

• 한국인터넷방송통신학회논문지
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• 제16권2호
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• pp.107-112
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• 2016

본 논문에서는 비선형 전달 특성을 갖는 채널에서 발생되는 부호간 간섭의 영향을 최소화시킬 수 있는 S-MMA (Sliced-Multi Modulus Algorithm) 등화 알고리즘에 가변 스텝 크기를 적용하여 등화 성능을 개선시킬 수 있는 알고리즘을 제안한다. 기존의 MMA 알고리즘에서 정상 상태에서 등화 성능과 misadjustment를 개선하기 위하여 S-MMA가 등장하였으며, 이들 알고리즘에서는 오차 신호의 크기에 따른 고정 스텝 크기로 적응하기 때문에 성능 개선에 한계가 있다. 이와 같은 문제를 극복하기 위하여 제안 알고리즘에서는 오차 신호의 크기에 비례하는 가변 스텝 크기를 적용하며, 개선 효과를 보이기 위하여 컴퓨터 시뮬레이션을 수행하였으며, 시뮬레이션 결과 제안 VSS S-MMA 알고리즘이 기존 S-MMA보다 등화 성능이 우월함을 확인하였다.

• Annals of Clinical Neurophysiology
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• 제6권1호
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• pp.31-34
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• 2004

Backgrounds: The pathway of the sural nerve (SN) is variable, but usually divided into medial and lateral sural branches joining the posterior tibial nerve (PTN) and the peroneal nerve (PN). The sural nerve may be affected by PN palsy. The frequency or the severity of SN involvement in peroneal palsy is not known. The purpose of the study is to investigate the frequency and the severity of the SN involvement by the peroneal nerve palsy. Methods: Total 85 patients were included with peroneal palsy. Amplitudes of distal peroneal, sural, and superficial peroneal nerves (SPN) were compared between normal and paralyzed sides. The frequency and severity of SN involvement by peroneal palsy were investigated. Results: Mean age was $48.4{\pm}17.4$ years old at the time of the test. Peroneal palsy was right side in 32, left in 38, and bilateral in 15 patients. Mean amplitudes of affected distal PN, SPN, and SN were $1.51{\pm}1.64mV$, $3.50{\pm}4.86{\mu}V$, and $10.42{\pm}6.59{\mu}V$ in right side, and $1.19{\pm}1.57mV$, $4.38{\pm}5.67{\mu}V$, and $11.06{\pm}6.87{\mu}V$ in left side, respectively. Sensory nerve action potential (SNAP) amplitude of the SN in the affected side was average $73.7{\pm}33.1%$ of normal, which was significantly lower than that in the normal side(p<0.01). The decrease of the sural SNAP amplitude was more than 15% in 39 out of 70 patients with unilateral peroneal palsy. Peroneal compound muscle action potential (CMAP) amplitude was not correlated with the amplitude of the sural SNAP. By complete peroneal palsy, SN SNAP amplitude was decreased to 4% of SNAP and $57.7{\pm}31.8%$ of that in normal side. Conclusions: PN injury without PTN involvement may induce reduction of sural SNAP amplitude. Because of the anatomic variation of SN, the electrophysiological findings are variable. It should be considered to interpret the location of the PN lesion.

• Structural Engineering and Mechanics
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• 제34권4호
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• pp.491-505
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• 2010

A computational analysis of the nonlinear free vibration of corrugated annular plates with shallow sinusoidal corrugations under uniformly static ambient temperature is examined. The governing equations based on Hamilton's principle and nonlinear bending theory of thin shallow shell are established for a corrugated plate with a concentric rigid mass at the center and rotational springs at the outer edges. A simple harmonic function in time is assumed and the time variable is eliminated from partial differential governing equations using the Kantorovich averaging procedure. The resulting ordinary equations, which form a nonlinear two-point boundary value problem in spatial variable, are then solved numerically by shooting method, and the temperature-dependent characteristic relations of frequency vs. amplitude for nonlinear vibration of heated corrugated annular plates are obtained. Several numerical results are presented in both tabular and graphical forms, which demonstrate the accuracy of present method and illustrate the amplitude frequency dependence for the plate under such parameters as ambient temperature, plate geometry, rigid mass and elastic constrain.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.213-219
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• 2003

Acoustic emission behavior during fatigue crack growth test was investigated under various loading condition. To describe the acoustic emission activity, counts rate (d/dn) was related with SIFR (stress intensity factor range, K). Results indicated that SIFR could be divided into two parts according to its relationship with counts rate. For $K<25_{MPa\sqrt{m}}$, counts rate was increased as the SIFR increased. However, for values greater than $25_{MPa\sqrt{m}}$ , decreasing behavior was shown. This behavior of counts rate corresponding SIFR was keeping the same trend regardless of load range or crack length. Acoustic emission response to the single overload was sudden drop and slow recovery in counts rate like crack growth retardation. Under variable loading condition, counts rate of each loading block was same as that of constant amplitude loading. Overall experimental data was somewhat scattered since sensitive characteristics of acoustic emission method. However, these empirical relations indicated that counts rate was uniquely correlate with single parameter, SIFR.