• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.4
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• pp.209-214
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• 2009

The purpose of this study is to investigate the effect exchanging water supply on the' rainwater in detached house. It is difficult to decide water supply amount for a closet in detached house, Therefore, to obtain water supply for closet in detached house, it used regression equation using 1,569 data of frequency of used closet and during 120 days. In detached house, the frequency of used closet is 14.6 times/day and water supply amount is $219 {\ell}/day$. The optimum rainwater tank size which is decided by regression equation and using weather data is $8.5\;m^3$. The effect exchanging water supply on the rainwater in detached house is up 50%.

• Steel and Composite Structures
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• v.32 no.6
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• pp.795-806
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• 2019

In this paper, free vibration of sandwich beam with flexible core resting on orthotropic Pasternak is investigated. The top and bottom layers are reinforced by carbon nanotubes (CNTs). This sandwich structural is modeled by Euler and Frostig theories. The effect of agglomeration using Mori-Tanaka model is considered. The Eringen's theory is applied for size effect. The structural damping is investigated by Kelvin-voigt model. The motion equations are calculated by Hamilton's principle and energy method. Using analytical method, the frequency of the structure is obtained. The effect of agglomeration and CNTs volume percent for different parameter such as damping of structure, thickens and spring constant of elastic medium are presented on the frequency of the composite structure. Results show that with increasing CNTs agglomeration, frequency is decreased.

• Journal of the Korea Society of Computer and Information
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• v.24 no.5
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• pp.179-186
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• 2019

While there have been a lots of studies on the use of cyber money, few researches proposed the results on relationships among quality factors, usage intention, and usage characteristics of cyber money in online business environment. Therefore, this study investigates the relationships between cyber money quality and usage intention of cyber money, and examines whether the usage characteristics(frequency, amount) of cyber money has moderating effect on the relationship between cyber money quality and usage intention of cyber money. Firstly, multiple regression analysis tells significant causal relationship between functional and emotional factors of cyber money quality and usage intention of cyber money. Secondly, dummy regression analysis shows usage characteristics of cyber money has the moderating effect on the relationship between cyber money quality and usage intention of cyber money. This paper concludes with some implications for both theory development and cyber money practice.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2005.11a
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• pp.255-258
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• 2005

A blind-mode integer frequency offset estimation algorithm is proposed for an OFDM system. Imperfect integer frequency offset estimation causes ambiguity in the data sub-carrier position. Morelli's blind integer frequency offiet estimation algorithm exploits the likelihood function by comparing the power in sub-carriers. It, however, shows performance degradation when there is the fractional frequency offset. The proposed algorithm solves this by using interpolation in the frequency domain. In this algorithm, it is exploited that the effect of the frequency offset is shown as a shift of power spectrum. By calculating the covariance of over-sampled samples, most approximate samples to integer point are obtained. It enables integer frequency offset estimation less affected by fractional frequency offset.

• Journal of Acupuncture Research
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• v.21 no.4
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• pp.75-84
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• 2004

Objective: To evaluate the treatment effect of Bee-venom Acupuncture on Neck Pain, which is well known for anti-inflammatory effect and function of activating immune system. Methods : We investigated 22 cases of patients with Neck Pain induced by soft tissue injury. One group was treated by Bee-venom Acupuncture therapy (Bee-venom Acupuncture Group :BA), the other group was treated by General Acupuncture therapy (None Bee-venom Acupuncture Group :GA). We evaluated the treatment effect of each group by few statistical analysis such as frequency analysis, Mann Whitney U test and spearman correlation analysis. Results : 1. In the age distribution of both groups, we found the highest frequency at the interval 35 to 45 years old. And in the number of medical treatment, Both groups show the highest frequency at the interval of less than four times. 2. BA was significantly decreased in VAS and clinical grade compared with GA. 3. We found significant correlation between period and number of treatment. So did we between VAS and clinical grade. Conclusion : As a result of thorough investigation, we could come to a conclusion that Bee-venom Acupuncture Group might have a notable effect on VAS and clinic grade.

• Korean Journal of Optics and Photonics
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• v.6 no.2
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• pp.135-141
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• 1995

Phenomenological nonlinear gain saturation effect on the noise characteristics of a multi-electrode DBR laser, when the lasing wavelength changes continuously, is presented theoretically. Using the optical transmission line theory, noise characteristics reliant on output power are analyzed by taking into account both the spontaneous enhancement factor K due to the distribution of the spontaneous emission along the active cavity and the nonlinear gain saturation effect. Spontaneous emission rate was increased due to an increase in injected current into the passive section, which in turn lead to increase in relative intensity noise (RIN) and frequency noise. Phenomenological nonlinear gain saturation was found to have significant effect on RIN and frequency noise characteristics. However. Iinewidth was found to decrease due to a phenomenological nonlinear gain saturation effect. ffect.

• Current Optics and Photonics
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• v.8 no.4
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• pp.345-354
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• 2024

The bit walk-off effect caused by fiber dispersion and carrier reuse in the base station (BS) are two key problems in radio-over-fiber (ROF) systems. In this paper, a novel frequency-octupling ROF system based on the Mach-Zehnder modulator (MZM) is proposed, which can overcome the bit walk-off effect and realize carrier reuse by inserting pilot signals. Theoretical analysis and simulation verification of the system are carried out. Under the condition of a Q factor greater than 6, the optical fiber transmission distance of the upper and lower links is more than 290 km and 80 km, respectively. The influence of the main device parameters of the system on the Q factor is analyzed when they deviate from their designed values. The system designed in this paper can not only effectively overcome the bit walk-off effect, but also solve the problem of downlink performance degradation and the limitation of tunability caused by conventional carrier reuse in ROF. The system can greatly increase the transmission distance and improve the performance of the system and has an important application prospect in ROF.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.634-637
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• 2005

A subjective index of sound quality when it hit him is required since human listening is very sensitive and complex. Sound quality evaluation it leads consequently rightly in each situation and it composes a sound quality factor. But one of the levels in interest frequency range is substitute we cannot see the tendency of frequency substitute at whole that is executes a clear voice evaluation. Design of experiment is used and dividing 12 equally in frequency domain, the sound quality using sharpness and annoyance is performed by modifying each of frequency domains. Design of experiment method reduces much number experiment very effectively and each main effect of domain solution analysis, such as a case of sharpness and annoyance, the change of domain (increase and decrease of sound pressure level, or change nil) can grasp a type of effect should have influenced to a sound quality, and it will be able to select the objective frequency domain which hits to the sound quality. Through these obtained results the physical changes of level at arbitrary frequency domain sensitivity can be adapted.

• International Journal of Automotive Technology
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• v.8 no.3
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• pp.337-342
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• 2007

A multi-objective optimization technique was implemented to obtain optimal topologies of the inner reinforcement for a vehicle's hood simultaneously considering the static stiffness of bending and torsion and natural frequency. In addition, a smoothing scheme was used to suppress the checkerboard patterns in the ESO method. Two models with different curvature were chosen in order to investigate the effect of curvature on the static stiffness and natural frequency of the inner reinforcement. A scale factor was employed to properly reflect the effect of each objective function. From several combinations of weighting factors, a Pareto-optimal topology solution was obtained. As the weighting factor for the elastic strain efficiency went from 1 to 0, the optimal topologies transmitted from the optimal topology of a static stiffness problem to that of a natural frequency problem. It was also found that the higher curvature model had a larger static stiffness and natural frequency than the lower curvature model. From the results, it is concluded that the ESO method with a smoothing scheme was effectively applied to topology optimization of the inner reinforcement of a vehicle's hood.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.2A
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• pp.103-109
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• 2006

OFDM system has a disadvantage of sensitiveness about the effect of the frequency offset caused by the discord of oscillators in transmitter and receiver. The frequency offset can be divided into integral part and decimal part. Although the frequency offset of integral part do not effect orthogonality between subcarriers, it makes the bit error probability become to 0.5 because of circular transient among transmitted data symbols. This paper proposes a new estimation scheme of the frequency offset of integral part by Maximum Likelihood (ML) demanding only one training symbol in multipath fading channel environment. This proposed scheme not only can reduce the number of training symbol but do not increase the complexity and it shows the better performance by simulation.