• 건축역사연구
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• 제6권1호
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• pp.9-25
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• 1997

The purpose of this study is to examine the standard scale of measuring a block of Kyongju(慶州), the Capital of the Silla Dynasty(B.C.57${\sim}$A.D.935). Through the study, it is clarified that 1). the block of Kyongju city is planned and divided by using the eight-Zhou-foot(周尺) as a standard scale, which is equivalent to the length of one-bo(보(步); 2). the distance between the center of the streets is around 100 bo and the width of the block is around 90 bo; 3). the distance between the streets is very near to the distance 167.054m of Jing-tian-zhi(井田制), which supports the use of Zhou-foot as a standard scale. As a result, it can be maintained that the city planning of Kyongju is related to that the Jing-tian-zhi of the Zhou Dynasty and the standard scale of measuring a block of Kyongju us executed by using the eight-Zhou-foot standard scale.

• 대한기계학회논문집B
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• 제30권11호
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• pp.1101-1106
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• 2006

To investigate a relation between fine scale eddies and particle dispersion in a near-wall turbulence, direct numerical simulations of turbulent channel flow laden particle are performed for $Re_{\tau}$=180. The motions of 0,8 million particles are calculated for several particle response times ($t_p$) which is the particle response time based on stokes’ friction law. The number density of particles has a tendency to increase with approaching the near-wall regions ($y^+$<20) except for cases of very small and large particle response times (i.e. $t_p$=0.02 and 15). Near the wall, the behavior and distribution of particles are deeply associated with the fine scale eddies, and are dependent on particle response times and a distance from the wall. The Stokes number that causes preferential distribution in turbulence is changed by a distance from the wall. The influential Stokes number based on the Burgers' vortex model is derived by using the time scale of the fine scale eddies. The influential Stokes number is also dependent on a distance from the wall and shows large value in the buffer layer.

• 천문학회보
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• 제36권2호
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• pp.51.1-51.1
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• 2011

We introduce new methods to measure distance in precision using large scale structure formation. The accuracy to determine geometrical factors is enhanced in comparison to the previous method known as BAO. We determine both D_A and H simultaneously as well as structure of growth of density fluctuations and peculiar velocities. Our method is independent of any given prior on large scale structure formation such as the shape of spectra.

• 융합신호처리학회논문지
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• 제2권3호
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• pp.86-92
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• 2001

미소 단위로 이동하는 물체의 이동 거리를 측정하기 위한 정밀 측정기기, 반도체 제조 장치, 공작기계 등의 위치 제어는 매우 중요한 요건이며, 이러한 장치들의 이동거리 측정에 대한 정확도는 전체 시스템의 성능을 좌우하게 된다. 따라서 정밀기기에서 이동 거리를 고정밀도로 측정할 수 있는 센싱 디바이스가 요구되며, 여기에는 레이저 간섭계의 분해능에 준하는 분해능을 갖고, 경제성 및 디지털 인터페이스에 대한 장점을 갖는 광학식 엔코더가 사용될 수 있다. 본 논문에서는 이동 거리를 측정하기 위해 회절 원리를 기초로한 고분해능 및 디지털 인터페이스가 용이한 간섭계형 리니어 스케일을 실험적으로 구성하였다. 그리고 이 리니어 스케일에서 발생된 간섭 신호는 제작된 광 검출기와 신호처리 회로를 통해 디지털화하였다. 그 결과 실험적으로 구성된 간섭계형 리니어 스케일은 스케일의 이동에 대하여 어떠한 분주 회로도 추가하지 않고, 단지 쉬운 광학적 구성으로 0.5$\mu\textrm{m}$의 분해능을 얻었다.

• 대한의용생체공학회:의공학회지
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• 제25권2호
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• pp.145-150
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• 2004

시각장애인의 시각보조를 위하여 공간 및 방향감각 보조시스템으로 초음파거리계 및 전자나침반을 개발하였다. 초음파거리계는 40 KHz 초음파의 반사를 이용하여 장애물까지 거리 정보를 거리에 비례하는 시간간격의 가청음 자극을 제공하며, 전자나침반은 자기저항브리지를 이용하여 지구자기장을 검출하고 자북 방향 정보를 이마주위의 진동모터를 통하여 촉각자극을 제공하도록 설계하였다. 초음파저리계의 측정범위는 0.065-3.26미터이며 전자나침반의 방향 분해능은 22.5도이다. 그리고 초음파거리계와 전자나침반을 통합한 일체형 시각보조시스템을 구현하였으며 이때 거리정보는 두부에서 진동모터의 위치로 전달하도록 하였다. 본 연구의 목표는 시각장애인의 공간 및 방향감각을 위한 실용적인 보조시스템을 구현하는 것이며, 본 보조시스템을 반복 사용함에 따라 시각장애인의 공간 및 방향감각 기능이 향상될 것으로 추측된다.

• 음성과학
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• 제3권
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• pp.167-176
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• 1998

Conventional time-scale modification methods have the problem that as the modification rate gets higher the time-scale modified speech signal becomes less intelligible, because they ignore the effect of articulation rate on speech characteristics. Results of research on speech perception show that the timing information of transient portions of a speech signal plays an important role in discriminating among different speech sounds. Inspired by this fact, we propose a novel scheme for modifying the time-scale of speech. In the proposed scheme, the timing information of the transient portions of speech is preserved, while the steady portions of speech are compressed or expanded somewhat excessively for maintaining overall time-scale change. In order to identify the transient and steady portions of a speech signal, we employ a simple method using LPC cepstral distance between neighboring frames. The result of the subjective preference test indicates that the proposed method produces performance superior to that of the conventional SOLA method, especially for very fast playback case.

• 실천공학교육논문지
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• 제16권4호
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• pp.577-585
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• 2024

This study analyzed the relationship between GPS-based physical activity patterns and mental health using Kaggle Student Life data. Data were collected over a 10-week period from 48 students at Dartmouth College through Android smartphones and included GPS, dark, and phone lock data, and measures such as the Patient Health Questionnaire-9 (PHQ-9), Loneliness Scale, the Positive and Negative Affect Schedule (PANAS), and Perceived Stress Scale. Using latitude and longitude data obtained from GPS measurements, various physical activity indicators were calculated, including the total distance traveled, average distance traveled, average distance traveled in the morning, average distance traveled in the afternoon, average distance traveled in the evening, and average distance traveled in the middle of the night. Pearson's correlation analysis was performed to explore the relationship between GPS-based physical activity patterns and mental health. The study results indicated a significant negative correlation between the average distance traveled in the afternoon and PHQ-9 scores. Results indicated that the higher the afternoon activity, the lower the depressive symptoms. There was a positive correlation be-tween the PANAS-Pos score and the average distance traveled in the evening, indicating that positive emotions tended to increase as evening activities increased. This finding suggests a relationship between physical activity at specific times and mental health.

• 한국연소학회:학술대회논문집
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• 한국연소학회 1997년도 제15회 KOSCO SYMPOSIUM 논문집
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• pp.163-173
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• 1997

This article presents an application of a large-scale structural mixing model (Broadwell et al. 1984) to the blowout of turbulent reacting jets discharging perpendicularly into an unconfined cross air-flow. In an analysis of a common stability curve, a plausible explanation can be made that the phenomenon of blowout is related only to the mixing time scale of the two flows. The most notable observation is that the blowout distance is traced at fixed positions at all times according to the velocity ratio R. Measurements of the lower blowout limits in the liftable flame agree qualitatively with the blowout parameter ${\varepsilon}$, proposed by Broadwell et al. Good agreement between the results calculated by a modified blowout parameter ${\varepsilon}^'$ and experimental results confirms the important effect of a large-scale structure in specifying the stabilization feature of blowouts.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2000
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• pp.73-80
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• 2000

The distance correction term -logA0 of the local magnitude scale was estimated for earthquakes in southern Korea using linear least-squares inversion and interpolation scheme. Total 1054 short-period velocity seismograms from 107 local events recorded at hypocentral distances ranging from 10 to 480 km were used in this study. Simulated Wood-Anderson amplitudes were obtained from velocity seismograms with use of revised Wood-Anderson instrument response with static magnification 2080, damping factor 0.7, and natural period 0.8 sec. The estimated distance correction term for southern Korea is found to be -logA0=1.137 log(r/17) + 0.001159(r-17) + 20, where r is hypocentral distance in kilometers. The attenuation rate of this distance correction term falls between those of southern California and eastern North America.

• 한국공작기계학회논문집
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• 제13권2호
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• pp.61-68
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• 2004

A non-contact precision measurement system is a theodolite system, a laser tacker and a photogrammetry system etc. Nowadays, the system reaches to a limit of measurement accuracy required from industrial product of middle and large scale. The one of the solutions for this problem is to maximize the accuracy of the existing measurement system. According to it we performed the study far a measurement accuracy of theodolite system when the distance between two theodolites is changed 1m to 5m. We could blow that the changes of distance affect the measurement accuracy of theodolite system and that the maximum measurement accuracy is $\pm$ 0.02 mm on theodolite distance 3∼4 m.