• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.78.1-78.1
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• 2010

We present the initial results of rest-frame optical spectroscopy of quasars at 3 < z < 5 from the AKARI space telescope mission program QSONG (Quasar Spectroscopic Observation with NIR Grism). QSONG is an AKARI phase-3 mission program which utilizes the unique capability of spectroscopy at 2.5-5 microns, and is adequate for detecting redshifted Balmer lines. We focus on how to overcome the noise induced from instrumental degradation, and report our measurements of supermassive black hole (SMBH) masses with well calibrated optical mass estimators.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2003.11a
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• pp.113-118
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• 2003

An investigation has been carried out on collision-induced dissociation (CID) in the development of an analytical protocol for the determination of polycyclic aromatic hydrocarbons (PARs) by ion trap tandem mass spectrometry. Two different considerations were used to choose the optimal CID conditions for complex matrix environmental samples, namely, to determine the highest signal-to-noise (SIN) ratio and the other to eliminate the background interferences originated from complex matrix samples. The PAR content of agricultural soil was measured to estimate overall distribution of PAR in throughout the country, we collected and analyzed 226 soil samples from paddy and upland soil. The average content of total PAR in all samples was 236 ${\mu}g$ $kg^{-1}$, and the range was from 23.3 to 2, 834 ${\mu}g$ $kg^{-1}$. The overall distribution of PAR was found to be closely related to the pollution sources, the size of city and the type of industry.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.63-68
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• 1999

Because misaligned shafts have caused noise, vibration, bearing failures, and stress concentration of coupling part, which decrease the efficiency and life of a shaft system, the proper alignment of shaft system should be monitored continuously in dynamic condition. To solve these problems under dynamic condition, a telemetry system is this study is used to find the condition of the least bending moment, which is known by analyzing the structure and stress induced by misalignment is investigated. The moment derived from two shaft strain at the nearby coupling is measured. The bending strain is measured 5 times for average in static state as well as dynamic state with 100~700 rpm.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.7 s.178
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• pp.1795-1800
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• 2000

One of the principal sources of vibration and noise in permanent magnetic machines is cogging torque, which is induced by interaction between the rotor poles and the stator teeth. For its analysis, using finite element analysis is very time consuming and the calculation of performance factors is extremely sensitive to the discretization. Especially, Maxwell stress tensor method is sensitive to the location of integral path. In this paper, a cogging permeance fuction is defined and replaced by the straight line. And it is assumed that the flux density acting on the stator's tooth side is the euqal to the flux density of the slot area. Using this definition and assumption, analytical calculation of cogging torque is presented and validated. And several reduction method is introduced.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.1
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• pp.69-78
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• 1997

Main sources of the vibration in gear driving system are transmission error and backlash. Transmission error is the difference of the rotation between driving and driven gear due to tooth deformation and profile error. Vibro-impacts induced by backlash between meshing gears lead to excessive vibration and noise in many geared rotation systems. Nonlinear dynamic characteristics of the gear driving system due to transmi- ssion error and backlash are investigated. Transmission error is calculated for spur gear. Nonlinear equation of motion for the gear driving system is developed with the calculated transmission error and backlash. Numerical analysis of the equation and the experimental results show the existence of meshing frequency, superharmonic compon- ents. Instability of the gear driving motion is found on the basis of Mathieu equation. Rattle vibration due to backlash is also discussed on the basis if nonlinear jump phenomenon.

• Korean Journal of Applied Biomechanics
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• v.16 no.2
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• pp.55-63
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• 2006

The purpose of this study was to investigate the effects of vibration exercise using surface electromyography. Seven male collegiate wrestlers were participated in this study. Each subject stood on the platform and the vibration was induced for 1min. WEMG8 EMG system was used to record muscle activity from Vastus lateralis, Biceps Femoris, Tibialis Anterior, and Gastrocnemius. The EMG data were sampled for 30 sec. during non-vibration and vibration half squat position, respectively. The raw data were band pass filtered to remove noise and full wave rectified Paired sample t-test were performed to see the differences of maximum and average EMG between non-vibration and vibration trials. The results indicated that vibration produced much more muscle contraction than that of non-vibration trial for all selected muscles even though the significant difference was found only from Biceps Femoris. This phenomenon was due to the individual differences so care must be taken to evaluate vibration intensity and position before personal training.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.5
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• pp.121-127
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• 2013

When input power is small, nonideal symmetric balance incomplete block design(BIBD) code design is effective in the spectral-amplitude-code(SAC) optical code-division multiple-access (OCDMA) system. But the number of simultaneous users is not sufficient. To overcome this property, we propose 2-D BIBD codes, where nonideal BIBD codes are used as spectral code and ideal BIBD codes are used as spatial codes. Analytical results show that the number of simultaneous users increases significantly.

• Proceedings of the Korean Geotechical Society Conference
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• 1992.03a
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• pp.115-135
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• 1992

The current design and construction practice prevailing in Korea has been investigated. From the survey the various problems at hand have been listed up and evaluated. The objectives of this research is to propose the means to solve the current problems from the result of the investigation. At the same time, the propagation characteristics of vibration and noise due to construction. especially pile driving. have been studied and the current regulation that restrict these construction nuisance has been investigated by field measurement.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.435-438
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• 1998

In this paper, Electret is formed to range voltage -5[kV] to -8[kV] by corona charging in PTFE film and sensor is manufactured by method of moments in sensing infra sonic. Charges of charged film are calculated also TSC measurement and induced potential of sensing electrode according to the charges is become aware of computer simulation. Electret Infra Sonic Transducer, which is designed and manufactured according to the potential and electric field simulation in using method of moments, is proved as it is effectively. Because sensitivity that measured under 10[Hz] is that average value of sensitivity rising rate is 6.34 [dB/oct] as average value is $\pm$1 [dB/oct] range -5[kV] to -8[kV] in corona charging film. As a result, it is believed that characteristic of acquired transducer can be application of medical treatment, industry, and animal life researches and the study of noise elimination, what's more, is required.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.503-507
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• 2004

The radiated sound pressure induced by low-velocity impact is obtained by solving the Rayleigh integral equation. This paper established the sound analysis procedure using impact analysis model. For structurally radiated noise, the sound field is directly coupled to the structural motion. Therefore the impact response should be analyzed. The impact response is computed using the spring-mass model. And the influence of damage on the sound pressure and impacted force history of laminated were investigated. The results show that both radiated sound pressure and impact force history are strongly influenced by damage on laminated.