• 대한전기학회논문지
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• 제41권9호
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• pp.1051-1059
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• 1992

In this paper, two general methods using time-series analysis in the functional separation of the myoelectric signal of human arm movements are developed. Autocorrelation, covariance method and sequential least squares algorithm were used to determine the model parameters and the order of signal model to describe six arm movement patterns` the forearm flexion and extension, the wrist pronation and supination, rotation-in and rotation-out. The confidence interval to classify the functions of arm movement was defined by the mean and standard deviation of total squared error. With the error signals of autoregressive(AR) model, the result showed that the highest success rate was obtained in the case of 4th order, and success rate was decreased with increase of order. Autocorrelation was the method of choice for better success rate. This technique might be applied to biomedical and rehabilitation engineering.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.28-31
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• 2002

This paper compared the surface roughness with variables before development of centerless grinding using far ferrule machining. In this paper, theoretical surface roughness is obtained from variables such as mesh number, rate of concentration of grinding wheel, wheel rotation of work-piece etc., and optimum condition of machining is selected. For satisfaction the technical side and economical side, centerless grinding using fur ferrule machining should be designed more than #600, 18.8% rate of concentration of grinding wheel, 1440rpm wheel rotation outwork-piece.

• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1998년도 PROCEEDINGS OF THE 14TH KACG TECHNICAL MEETING AND THE 5TH KOREA-JAPAN EMGS (ELECTRONIC MATERIALS GROWTH SYMPOSIUM)
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• pp.161-164
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• 1998

Erbium doped garnet crystals were grown by Czochralski method. Relationshipes between crystal quality and crystal growth factors such as pulling rate, rotation rate and concentration of active ions and sensitizers were investigated. Optimum pulling and rotation rate for high quality Er:YAG crystal were 1 mm/hr and 20 rpm and for Er,Cr:YSGG crystal 2-4 mm/hr and 10 rpm respectively. The size of the crystals grown was up to 20-30 mm in diameters and 95-135 mm in length. Er:YAG crystal grown under the nitrogen atmosphere was pink and transparent and Er,Cr:YSGG under the 98% {{{{ { N}_{ 2} }}}} and 2% {{{{ { O}_{2 } }}}} was dark green and transparent. Under the polarizing microscopic observations with crossed polar, striations and {211} core facets were detected. Spectroscopic properties for Er,Cr:YSGG laser rods with <111> axis, 80 mm in length and 6.3 mm in diameter for medical laser applications of 2.79 ${\mu}$m wavelength were manufactured and then laser oscillation was achieved.

• 대한기계학회논문집B
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• 제24권4호
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• pp.578-588
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• 2000

A low-Reynolds-number second moment turbulence closure is improved with the aid of DNS data. For the model coefficients of pressure-strain terms, we adopted Shima's model with some modification. Shin and Choi's new dissipation-rate equation is employed to simulate accurately the turbulence energy dissipation rate distribution in the near wall sublayer. The results of computations are compared with DNS, LES data and experimental data for turbulent plane channel flow with rotation about spanwise axis. The present second moment closure achieves a level of agreement similar to that for the non-rotating. In particular, it accurately captures the distribution of turbulence energy dissipation rate in the near wall region.

• 반도체디스플레이기술학회지
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• 제17권4호
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• pp.91-96
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• 2018

In this study temperature distribution and gas flow inside a planetary type reactor in which a number of satellites on a spinning susceptor were rotating were analyzed using numerical simulation. Effects of flow rates on gas flow and temperature distribution were investigated in order to obtain design parameters. The commercial computational fluid dynamics software CFD-ACE+ was used in this study. The multiple-frame-of-reference was used to solve continuity, momentum and energy conservation equations which governed the transport phenomena inside the reactor. Kinetic theory was used to describe the physical properties of gas mixture. Effects of the rotation speed of the satellites was clearly seen when the inlet flow rate was small. Thickness of the boundary layer affected by the satellites rotation became very thin as the flow rate increased. The temperature field was little affected by the incoming flow rate of precursors.

• 한국통신학회논문지
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• 제35권11A호
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• pp.1073-1077
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• 2010

본 논문은 Reyleigh 페이딩 채널 환경에서 다이버시티 이득 4를 얻는 새로운 4차원 성상회전(constellation rotation, CR) 기법을 제안한다. 제안된 기법은 기존의 한 변의 CR을 이용한 2차원 CR 기법과 달리 연속된 두 QAM 신호들에 대하여 두 번의 CR을 수행함으로써 동작한다. 전산 실험 결과 새로운 기법은 기존의 기법에 비해 채널 부호화의 전송률과 페이딩 채널 내 erasure 확률 값이 증가할수록 더욱 큰 성능 향상을 보인다. 또한 새로운 기법은 사용되는 각도 값들을 바꾸어 기존의 기법으로 쉽게 전환 가능하며 따라서 송신 시스템 구현 측면에서 큰 장점을 갖는다.

• 대한물리의학회지
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• 제10권1호
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• pp.115-120
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• 2015

PURPOSE: Vertebrobasilar insufficiency (VBI) should be carefully assessed in patient for whom manipulation of the cervical spine is to be undertaken. The purpose of this study was to investigate the changes in posterior cerebral artery blood flow velocity following head and body positioning by transcranial doppler ultrasonography (TCD) in healthy subjects. METHODS: Twenty two healthy female (mean age $20.77{\pm}1.30yrs.$) participants volunteered to participate in the study. None of the participants had a history of neck pain or headache within the last 6 months. To evaluate the cerebral blood flow, we measured the mean flow velocity of the posterior cerebral artery unilaterally (right side). The blood flow velocity was measured under 3 different head positions (in a neutral head position, ipsilateral head rotation and contralateral head rotation position) and 2 different body conditions (supine position and sitting position). RESULTS: The mean blood flow velocity of posterior cerebral artery was decreased in body positioning from supine to sitting (p<.05), but the decreased rate of blood flow velocity in posterior cerebral artery did not change significantly between ipsilateral head rotation and contralateral head rotation (p>.05). CONCLUSION: These result of our study show that body positioning (sitting and supine) affect the blood flow velocity in posterior cerebral artery.

• 한국결정학회지
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• 제2권2호
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• pp.32-40
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• 1991

The effects of compositional variation, rotation speel and pulling rate on the growth of optical quality Bi120e02(1 crystals were examined. It was found to flatten the shape of crystal-melt interface for yowing a single crystals less than about 30mm in diameter at the rotation speed of 50rpm. Diameter of crystals with flat interface was increased as the pulling rate. The precipitation of Bi40e3012 phase set limits to pulling rate of BGO crystals. Precipitate-free BGO crystals were grown under pulling rate of 2mm l hr which released the stress resulted from too hi어 Pulling rate, and from 6. IBi203·GeO2 batch composition obtained by addition of 0.1 mole Bi203 into Bi-deficient melts to fill up the deficiency resulted from gradual volatilization of Bi2O). The pale-yellow colored crystals had good quality in that dislocation density was less than 103pits/cm, and it also exhibited transmittance of 70% and optical activity of 23°/mm. and SAW velosity was measured 1700m/sec on 111 cut 110 propagating BGO crystals. The SAW filter with electrode thickness of 9.8um was fabricated by using the electron beam and dry etching technique, it makes Bi12GeO20 devices intersting for color TV IF with half device size.

• 대한기계학회논문집B
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• 제31권1호
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• pp.76-82
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• 2007

The present study investigated the effects of channel rotation and bleed flow on heat/mass transfer in a square channel with $45^{\circ}$ rib turbulators. The bleed holes were located between the rib turbulators on the leading surface and those on the trailing surface case by case. The tests were conducted under the conditions of various bleed ratios (0.0, 0.2, 0.4) and rotation numbers (0.0, 0.2, 0.4) at Re=10,000. The results suggested that heat/mass transfer characteristics were influenced by the Coriolis force, decrement of main flow rate, secondary flow by angled ribs and bleed hole location. As the bleed ratio (BR) increased, the heat/mass transfer decreased on both surfaces due to the reduction of main flow rate. With increment of the rotation number, heat/mass transfer also decreased and almost the same because the reattachment of the secondary flow induced by angled ribs was weakened on the leading surface and the secondary flow was disturbed on the trailing surface by the Coriolis force.

• Journal of electromagnetic engineering and science
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• 제7권4호
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• pp.169-174
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• 2007

This paper presents a method of superimposing the rotation phases over the pilot and data symbols in order to reduce the peak-to-average power ratio(PAPR) in orthogonal frequency division multiplexing(OFDM). The phases of the rotation vector are added to those of the pilot symbols and those of the data symbols by interlaying them between any two pilot symbols. The receiver restores the data symbols by utilizing the channel estimation of the pilot symbols. Therefore, the bandwidth efficiency is improved by not using the subcarriers that are assigned for the reduction of the PAPR. Also, the enormous increase of the bit error rate which would be caused by incorrectly receiving the side information, i.e. the phases of the rotation vector, is prevented. The simulation results of the bit error rate performance for the BPSK are given using the COST-207 channel model.