• 대한방사선치료학회지
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• 제27권1호
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• pp.73-78
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• 2015

목 적 : 본 연구는 위상 기반 방식으로 배열 된 사차원 전산화 단층 촬영 영상(4DCT, 4-dimensional computed tomography)를 이용하여 진폭 기반 방식으로의 재구성 하였을 때의 위상 차이를 분석하였다. 대상 및 방법 : 2015년 02월부터 03월 까지 호흡동조 방사선 치료를 받은 간암 환자 10명의 사차원 전산화 단층 촬영 영상을 대상으로 분석 하였다. RPM respiratory gating (RPM 1.7.5, Varian, USA)장치를 이용하여 위상 기반 배열 방식의 호흡주기별 영상을 획득 하였으며, 획득된 호흡 주기별 영상은 치료계획시스템(Pinnacle 9.2, Philips, USA)을 이용하여 호흡주기별 복부의 움직임 값을 측정하였다. 최대 호기(50%)와 최대 흡기(0%)에서의 복부 움직임을 진폭으로 하여 10개 위상의 진폭 기반 호흡위상을 재구성하고, 이를 위상 기반 사차원영상촬영영상의 호흡 위상과 비교하였다. 결 과 : 위상 기반 및 진폭 기반 사차원단층촬영영상으로 재구성한 영상에서의 위상 차이는 최대 30% 호흡위상에서 확인할 수 있었으며, 30% 호흡 위상에서 평균 0.13 cm (최대 0.24 cm)의 위치 차이를 확인할 수 있었고, 동일 측정 점 위치가 가지는 위상차는 30% 위상에서 평균 8.7%(최대 16.5%)의 위상차를 확인하였다. 전체 호흡 구간에서 평균 위치 차이는 0.4 cm, 평균 위상 차이는 13.0% 임을 확인하였다. 결 론 : 본 연구 결과는 위상 기반 방식으로 배열된 4DCT 영상을 진폭 기반 방식으로의 변환하였을 때 계산 값과 실측값을 분석한 결과 최대 16.5% 의 위상차가 발생함을 확인하였다.

• 한국생산제조학회지
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• 제22권4호
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• pp.673-679
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• 2013

This study investigates the strength durability of an automotive front bumper subjected to vibrations during driving. Through structural analyses,the maximum equivalent stresses of models 1 and 2 were found to be 187.09 and 278.4 MPa, respectively. The maximum deformations of models 1 and 2 were 1.3772 and 2.675 mm, respectively. As model 1 shows less deformation than model 2, itis stronger than model 2. Models 1and 2 show natural frequencies within 230 Hz as the range of the maximum harmonic response frequency. Models 1 and 2 have maximum amplitude displacements of 0.105 and 0.154 mm at critical frequencies of 159 and 110 Hz, respectively. As model 1 has a higher critical frequency than model 2, it has more strength durability than model 2. This study result can be effectively utilized for the design of a front bumper by investigating prevention against damage and its strength durability.

• 한국국방경영분석학회지
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• 제8권1호
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• pp.77-98
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• 1982

Experiments have been performed for estimating the individual muscle capabilities of the biceps brachii and the quadriceps femoris muscle. The surface EMG has been recorded on the bellies of the biceps brachii and the quadriceps femoris muscle during isometric contractions at $50\%,\;75\%,\;and\;100\%$ MVC. The rectified EMG amplitudes of the maximum voluntary contraction (MVC) were in the range of $2.8\~3.0\;mV\;and\;6.9\~7.2\;mV$ the biceps brachii and the quadriceps femoris, respectively. In the biceps brachii, Type S motor units were recruited in the range of $41\~49\%$ MVC; and Type F motor units were recruited in the range of $51\~59\%$ MVC, In the quadriceps femoris, Type S, Type SF, and Type F motor units were recruited in the ranges of $31\~38\%,\;33\~48\%$, and $21\~29\%$ MVC respectively.

• 비파괴검사학회지
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• 제6권2호
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• pp.17-36
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• 1987

In this experimental research, fracture mechanisms of spheroidal graphite cast iron (As Cast, annealed and normalized) were investigated by using Acoustic Emission (AE) technique. In this study, the data (AE signal) are digitized and processed with the 8 bits micro-computer (APPLE II) connected to the AE measuring device without data processing unit. The source of AE signal was estimated by fractography analysis. The results obtained in this experimental study are summarized as follows : For the heterogeneous materials (spheroidal graphite cast iron) with inclusions which may considered as cracks, it is found that low and high AE amplitude appear simultaneously and the load is found to be fluctuated in the final stage of deformation. But the lad is not fluctuated in tension test with low AE amplitude only. AE is measured within elastic region and it is confirmed that 0.2% offset yield load agrees approximately with the load point where AE counts decrease steeply after the point of maximum AE counts.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.2082-2086
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• 2003

This paper presents the analysis of satellite received signal by focus on the new prediction method for amplitude scintillation expression. A predict method based in the relationship of standard deviation values and the peak to peak values of amplitude scintillation in various of time period and various of sampling rate of signal variation. The principal techniques finding, the proper sampling rate and time interval, for the best expression method. The experiment has been performed in Bangkok of Thailand, at King Mongkut's Institute of Technology, Ladkrabang, data collected in C-Band and Ku-Band on high elevation angles. The result of analysis shows the relationship between two methods is given by ${\sigma}_x={\alpha}(P-P)+{\beta}$. The value of ${\alpha}$ depends on sampling rate by closely with three-minute maximum time interval.

• 대한기계학회논문집
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• 제17권9호
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• pp.2153-2161
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• 1993

Self-tuning control algorithms for an input-amplitude constrained system are developed and implemented. Magnitude of control input for small motors is generally restricted to narrow bound due to actuator saturation. The gain-adjusted control algorithm and the bounded-gain control algorithm proposed in this study yield smoother control input variations within the magnitude constraints comparing with the existing Clarke's suboptimal control algorithm. In the gain-adjusted control algorithm, the feedforward gain is adjusted using maximum gain, while in the bounded-gain control algorithm, the feedforward gain is bounded using weighting factor. For the DC servo motor control, the system performances of the proposed algorithms are compared with those of the existing algorithm by computer simulation and experiment. It is shown that the input variations of the proposed algorithms are smoother as compared with the existing algorithm.

• 비파괴검사학회지
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• 제23권6호
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• pp.577-582
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• 2003

This paper describes a new technique for thickness measurement of a very thin layer less than one-quarter of the wavelength of ultrasonic wave used in the ultrasonic pulse-echo measurements. The technique determines the thickness of a thin layer in a tapered medium from constructive interference of multiple reflection waves. The interference characteristics are derived and investigated in theoretical and experimental approaches. Modified total reflection wave g(t) defined as difference between total and first reflection waves increases in amplitude as the interfacial layer thickness decreases down to zero. A layer thickness less than one-tenth of the ultrasonic wavelength is measured using the maximum amplitude of g(t) with a good accuracy and sensitivity. The method also requires no inversion process to extract the thickness information from the waveforms of reflected waves, so that it makes possible to have the on-line thickness measurement of a thin layer such as a lubricating oil film in thrust bearings and journal bearings during manufacturing process.

• Journal of electromagnetic engineering and science
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• 제7권1호
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• pp.1-6
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• 2007

Recently, Mc(Multi-code) modulation/demodulation(modem) technique has been explored for high speed data transmission in wireless environment. The conventional Mc modem generates some side effects such as allocating Walsh codes, which motivates to propose a novel Mc modem method with sub-code. Our proposed system should expanded the size of sub-code to provide high-rate data transmission, which also affect adversely to the performance of the system with high PAPR(Peak to Average Power Ratio). Thus, in this paper, we propose a novel pre-coded Multi-Dimensional HCOC(High Capacity Orthogonal Code) Mc modem technique to reduce the high PAPR, which enables the performance improvement. This proposed system can be easily designed by concatenating HCOC Mc modem with the generic Mc modem. The pre-coding technique that is used in this paper is CAC(Constant Amplitude Coding), that helps the system maintain the constant transmission power and reduce the maximum transmission power.

• 한국정밀공학회지
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• 제1권2호
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• pp.58-68
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• 1984

In this study, the static and dynamic components of cutting resistance were measured with tool dynamometer (Swiss, pieso-electric type) when S45C, A1-alloy and brass were drilled under the some variable conditions. The results obtained are as follows; 1) The dynamic components of these cutting resistance are not related to the depth of drilled hole. 2) The static and dynamic components of cutting resistance are increased in accordance with the increase of feed and drill diameter. 3) The dynamic components of thrust force are increased in accordance with the increase of spindle speed. 4) The rate of the dynamic component to the static component is 0.3 .approx. 0.5 in torque, 0.1 .approx. 0.2 in thrust force. 5) The characteristic of the tool system is affected in dynamic component of cutting resistance, and the creasted frequency and amplitude of the chip are determined by the crilled materials. 6) The maximum amplitude of the dynamic component is increased proportionally in accordance with the feed rate and the spindle speed.

• Journal of electromagnetic engineering and science
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• 제16권4호
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• pp.241-247
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• 2016

This paper proposes the design and measurement of a 6-18 GHz front-end receiver module that has been combined into a one- channel output from a two-channel input for electronic warfare support measures (ESM) applications. This module includes a limiter, high-pass filter (HPF), power combiner, equalizer and amplifier. This paper focuses on the design aspects of reducing the noise figure (NF) and matching the phase and amplitude. The NF, linear equalizer, power divider, and HPF were considered in the design. A broadband receiver based on a combined configuration used to obtain low NF. We verify that our receiver module improves the noise figure by as much as 0.78 dB over measured data with a maximum of 5.54 dB over a 6-18 GHz bandwidth; the difference value of phase matching is within $7^{\circ}$ between ports.