• Proceedings of the Korea Contents Association Conference
• /
• 2003.05a
• /
• pp.474-479
• /
• 2003

We discussed the usage of a radio resource, the spectrum allocation and the trends of policy about 5㎓ band in other countries, We studied about the technical regulation on high speed wireless access system and the spectrum allocation of ISM bard in 5㎓ bard for other countries. We also analyzed the efficient use of radio resource, the method of frequency sharing and the calculation of spec01m requirement in noel to progress the high speed wireless access system In addition We proposed the schemes of domestic spectrum allocation for high speed wireless access system at 5㎓ band

• KCID journal
• /
• v.18 no.2
• /
• pp.25-32
• /
• 2011

The 21 livestock farms considering future installation of biogas systems were studied. These farms were examined how to raise the livestock, to treat manure, to operate facility with respect to manure characteristics. The 15 farms out of 21 farms have applied to the marine dumping and consignment treatment for treating manure and even farms which have equipped liquid fertilizing system have less capacity facility than legal standards. Characteristics of manure were affected by the scale of swine barn, clean water usage, frequency of cleaning, cleaning method, feces-urine separating method, etc. Retention time in storage (over 20 days) has resulted in lower concentration of organic matter which could reduce biogas production. This indicates that systematic barn management system is required. Inhibition tests showed that disinfectant and citric acid did not affected digestion rates at 10 times higher concentration than recommendation. However hypochlorous acid is likely to affect the anaerobic microbial activity.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2007.05a
• /
• pp.280-285
• /
• 2007

This study described the designed and construction of uninterruptible power supply(UPS) system for large scale computer system KISTI's supercomputer system is serviced 24 hours and power supply should be achieved in stable voltage and frequency range. We analyzed the electric power usage for 4 years, and we found several optimal parameters for new design of UPS configuration.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.27 no.5
• /
• pp.793-801
• /
• 1990

A single mode fiber-optic Mach-Zehnder interferometer for the measurement of strain is described. A fiber-optic strain gauge with great resolution and wide measurement range is realized. In order to varify the dynamic response, the measurements of strain below 1涅 with frequency range 5-50Hz are compared with a semiconductor strain gauge. We report theoretical evaluation for mechanical analysis, PZT-plate, the phase change in a fiber-optic strain gauge and a semiconductor strain gauge. The dynamical characteristics of a fiber-optic strain gauge and a semiconductor strain gauge output siganl show equivalent behavior. This result is shown in very good usage as the dynamical measurement of the low strain below 1涅 by this system.

• IEMEK Journal of Embedded Systems and Applications
• /
• v.7 no.5
• /
• pp.277-284
• /
• 2012

To meet the usage of discrete wavelet transform (DWT) on potable devices, this paper implements 2-level DWT using a reference many-core processor architecture and determine the optimal many-core processor. To explore the optimal many-core processor, we evaluate the impacts of a data-per-processing element ratio that is defined as the amount of data mapped directly to each processing element (PE) on system performance, energy efficiency, and area efficiency, respectively. This paper utilized five PE configurations (PEs=16, 64, 256, 1,024, and 4,096) that were implemented in 130nm CMOS technology with a 720MHz clock frequency. Experimental results indicated that maximum energy and area efficiencies were achieved at PEs=1,024. However, the system area must be limited 140mm2 and the power should not exceed 3 watts in order to implement 2-level DWT on portable devices. When we consider these restrictions, the most reasonable energy and area efficiencies were achieved at PEs=256.

• Structural Engineering and Mechanics
• /
• v.59 no.6
• /
• pp.1055-1070
• /
• 2016

The aim of this experimental study is to investigate the free vibration and buckling behaviors of hybrid composite beams having different span lengths and orientation angles subjected to different impact energy levels. The impact energies are applied in range from 10 J to 30 J. Free vibration and buckling behaviors of intact and impacted hybrid composite beams are compared with each other for different span lengths, orientation angles and impact levels. In free vibration analysis, the first three modes of hybrid beams are considered and natural frequencies are normalized. It is seen that first and second modes are mostly affected with increasing impact energy level. Also, the fundamental natural frequency is mostly affected with the usage of mold that have 40 mm span length (SP40). Moreover, as the impact energy increases, the normalized critical buckling loads decrease gradually for $0^{\circ}$ and $30^{\circ}$ oriented hybrid beams but they fluctuate for the other beams.

• Journal of the Korean housing association
• /
• v.21 no.1
• /
• pp.141-150
• /
• 2010

The purpose of this study is to suggest a social environment to active communities in apartment housing, on the basis of the residents' different social environments of two apartment complexes having their own respective community spaces. A questionnaire was responded by 434 housewives residing in the two apartment complexes which have their own respective space usage and programs in the community spaces larger than is legally specified. The questionnaire comprised items such as neighborhood consciousness, social intercourse, needs of community program diversity. The frequency analysis, the t-test, ANOVA, chi-square analysis were used for the comparison of characteristics of the two apartment complexes. The results of the social environment are as follows. The neighborhood consciousness, social intercourse of residents, and their attitude for participation in the common activities differed according to the residents' socio-demographic characteristics (age, education, number of family, average household income), complex distinctions (presence of clubs, community spaces, and community programs), and the attitude of constructors to foster it. Residents' participation rate and their participation intention showed positive correlation.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.24 no.8A
• /
• pp.1179-1186
• /
• 1999

Multi-carrier CDMA technique is more attractive in wireless communication system. It can support the effect of frequency diversity with higher spectral efficiency. In this paper, pilot symbol structure was proposed to estimate chann디 paramenters for MC-CDMA system and we analyzed the perfoemance of proposed MC-CDMA which compensates the received signals using the pilot symbols for link transmission. At first, we proposed the new method of pilot's usage for reverse link transmission that can distinguish accessing users whose signals undergo diggerent channels. And we analyzed the performance of coherent MC-CDMA reception using estimated channel parameters

• Journal of Information Technology Applications and Management
• /
• v.21 no.1
• /
• pp.1-16
• /
• 2014

Cyberloafing is as counterproductive behavior because it is the act of using internet for personal purposes which can affect employees' productivity, especially when done excessively (more than 4 hours a week). The objective of this study was to analyze whether gender and education level had significant effect on cyberloafing among generations in the workplace. From 267 respondents, gender was not found to have impact on cyberloafing because female and male respondents had the same frequency of low level cyberloafing. However, female had higher excessive cyberloafing than male. Gen Y had significant impact on the relationship between education and cyberloafing but Gen Y with diploma degree was revealed to have excessive cyberloafing. Furthermore, Gen X had started combining professional and personal lives throughout their daily lives. Hence, organizations should foster a culture of hard work by giving challenging job with clear target and worthy incentive but still implementing internet usage policy.

• Earthquakes and Structures
• /
• v.18 no.3
• /
• pp.313-320
• /
• 2020

The usage of conventional tuned mass damper (TMD) was proved as an effective method for passive mitigating vortex-induced vibration (VIV) of a bridge deck. Although a variety of linear TMD systems have been so far utilized for vibration control of suspension bridges, a sensitive TMD mechanism to wind spectrum frequency is lacking. Here, we introduce a bistable tuned mass damper (BTMD) mechanism which has an exceptional sensitivity to a broadband input of vortex shedding velocity for suppressing VIV in suspension bridge deck. By use of the Monte Carlo simulation, performance of the nonlinear BTMD is shown to be more efficient than the conventional linear TMD under two different wind load excitations of harmonic (sinusoidal) and broadband input of vortex shedding. Consequently, an appropriate algorithm is proposed to optimize the design parameters of the nonlinear BTMD for Kap Shui Mun Bridge, and then the BTMD system is localized for the interior deck of the suspension bridge.