• CRM연구
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• v.3 no.1
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• pp.29-47
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• 2010

This study is intended to examine the effect of characteristics of museum visitors and visit type on perceived relative status, aesthetic responses, and perceived visit benefits, which in turn affect visitor satisfaction and personal and social participatory behaviors. Research was held for four weeks. A total of 308 questionnaires were collected out of 315 distributed. However, additional 15 were excluded due to inadequate responses. The findings of the study are as follows: While museum visitor characteristics yielded significant effects on the perceived relative status and perceived visit benefit, it did not have significant effects on aesthetic responses. Additionally, while visit types showed considerable impact on perceived relative status, it did not yield significant effect on aesthetic responses or the perceived visit benefit. Perceived relative status of a museum had positive effects on aesthetic responses, but not on the perceived visit benefit. Furthermore, while perceived relative status did not have significant effect on visitor satisfaction, it did have evident effects on the aesthetic response and the perceived visit benefit. Lastly, greater visitor satisfaction was confirmed to contribute to greater participatory behavior in various prospective programs and events offered by museums. Hence, it would be imperative for museums to gear their attention to encourage internal participatory behaviors such as visitor education, donation and charity events, which would consequently transcend to viewing museums more as a public space shared by the general public.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.2
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• pp.208-217
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• 2010

This paper presents a novel 10 GHz bio-radar system based on a frequency multiplier and phase-locked loop(PLL) for non-contact measurement of heartbeat and respiration rates. In this paper, a 2.5 GHz voltage controlled oscillator (VCO) with PLL is employed to as a frequency synthesizer, and 10 GHz continuous wave(CW) signal is generated by using frequency multiplier from 2.5 GHz signal. This paper also presents the noise characteristic of the proposed system. As a result, a better performance and economical frequency synthesizer can be achieved with the proposed bio-radar system. The experimental results shows excellent bio-signal measurement up to 100 cm without any additional digital signal processing(DSP), and the proposed system is validated.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.2
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• pp.131-140
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• 1998

MAI(Multi-Access Interference) and fast channel variation due to the fading environment are the major problems in the mobile CDMA communication systems. Recently, interest has been increasing in applying the Adaptive Linear MMSE Detector to MAI cancellation in the CDMA reverse link. In this paper, we propose a modified Adaptive Linear MMSE Detector structure which can be used in Long-duration code CDMA system in the presence of independent Rayleigh fading. We use independent multiple tap-weight vector structure to cope with the variation of spreading sequence pattern between neighbor symbols because of the Long-duration code. In this case, more exact channel parameter estimation is required. To solve this problem, we use coherent CDMA structure which can track the channel parameters like amplitude and phase by employing the low power pilot channel in the CDMA reverse link.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.8
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• pp.1818-1826
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• 2014

Time-variant sea surface causes a forward scattering and Doppler spreading in received signal on underwater acoustic communication system. This results in time-varying amplitude, frequency and phase variation of the received signal. In such a way the channel coherence bandwidth and fading feature also change with time. Consequently, the system performance is degraded and high-speed coherent digital communication is disrupted. In this paper, quadrature phase shift keying (QPSK) performance is examined in two different sea surface conditions. The impact of sea surface scattering on performance is analyzed on basis of the channel impulse response and temporal coherence using linear frequency modulation (LFM) signal. The impulse response and the temporal coherence of the rough sea surface condition were more unstable and less than that of the calm sea surface condition, respectively. By relating these with time variant envelope, amplitude and phase of received signal, it was found that the bit error rate (BER) of QPSK are closely related to time variation of sea surface state.

• Korean Architects
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• s.496
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• pp.71-76
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• 2010

본 연재는 앞으로 2회에 걸쳐 '네덜란드의 건축정책(Architectural Policy)'과 '네덜란드의 건축센터(Architecture Centers)'의 역할을 살펴보게 될 것이다. 이를 통해 각각 중앙 정부와 지역이 어떻게 상호 관계를 맺으며 네덜란드의 건축과 도시를 조율하고 발전시켜나가는 건축 정책의 중요한 주체로서 작용하는지 살펴보고자 한다. 이러한 복합적인 층위의 역할과 그 협력 관계를 이해하는 것은 오늘날 세계 건축계를 이끌어 가고 있는 네덜란드의 건축문화를 이루는 원동력이 무엇인지를 아는 데에 있어 매우 중요한 일이다. 네덜란드는 세계 최초의 정부 주도로 수립된 건축정책을 통해 지난 20여 년 간 건축의 공공성을 표방하며 자국의 건축문화를 발전시켜왔다. 네덜란드의 건축문화는 개별적인 작가들에 의해서라기보다는 건축가(군), 건축기관, 정부 등 여러 주체들에 의해 발전되었으며 건축 정책을 통해 지속적인 시스템을 구축했다는 점을 주목해야 한다. 네덜란드 정부는 건축정책을 수립하고 그 실행을 전문적 건축기관에 일임함으로써 전문가들이 분야의 전문성과 폭넓은 네트워크를 바탕으로 건축의 공공성을 지향하고 건축실천의 방향성을 유도하는 역할을 하고 있다. 한편 지역의 자발적인 움직임으로 설립, 운영되는 지역 건축센터들은 지역의 폭넓은 커뮤니티에의 접근성을 바탕으로 정부의 적극적인 지원 속에서 중앙의 건축정책의 방향성을 지역의 커뮤니티에 전달하고 지역의 이슈를 발굴하고 발전시킨다. 본 연재는 시대적 변화 속에서 개별적 주체들의 의식 성장으로 하향식 주도가 더 이상 작동하기 힘들며 관심과 동기가 다른 다양한 주체들과의 협의와 협력이 불가피해지고 공공성의 대변자 역할을 했던 건축, 도시계획의 위상이 근본적으로 변화를 겪으면서 공공성에 대한 이해의 재정립이 요구되는 현 시대에 네덜란드의 건축정책과 건축센터의 사례를 통해 우리에게 시사하는 바를 찾고자 한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.6C
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• pp.623-628
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• 2006

This paper addresses the frequency offset estimation problem in the presence of the timing error for OFDM systems. When the timing error exists, the correlation value used for the frequency offset estimation could be reduced significantly due to the timing error, resulting in considerable degradation in estimation performance. In this paper, using the coherence phase bandwidth (CPB) and a threshold, a novel frequency offset estimation scheme is proposed and based on which, an efficient timing error estimation scheme is also proposed for the re-estimation of the frequency offset. The performance comparison results show that the proposed frequency offset estimation scheme is not only more robust to the timing error but also has less computational complexity, as compared with the conventional schemes. It is also demonstrated by simulation that theproposed timing error estimation scheme gives a reliable estimate of the timing error.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.4
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• pp.553-564
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• 2000

In this thesis, mobile communication channel with multi-path fading which is major factor of performance degradation of DS-CDMA system has been considered. An MRC diversity and error correcting coding technique have been used to improve performance of MFSK-MDPSK/DS-CDMA system. The MFSK-MDPSK/DS-CDMA system performance has been obtained quantitatively by the numerical analysis. the modulations under consideration are noncoherent M-ary frequency shift keying(MFSK) and an MFSK based joint frequency phase modulation utilizing MFSK/DS-CDMA and MDPSK-DS-CDMA systems the MFSK-MDPSK/DS-CDMA system obtain a better performance . Also, the error performance of MFSK-MDPSK/DS-CDMA system in Nakagami fading environments is improved by increasing the number of diversity branch and coding gain.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.9
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• pp.1195-1207
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• 1998

Periodic pulsations in the static pressure near turbine surfaces as blade rows move relative to each other is one of the important sources of turbine unsteadiness. The present experiment aims to investigate the effect of the static pressure pulsations on the interaction of film coolant flows from two rows of staggered holes with mainstream and its effect on film cooling heat transfer. Potential flow pulsations are generated by the rotating shutter mechanism installed downstream of the test section, The free-stream Strouhal number based on the boundary layer thickness is in the range of 0.033 - 0.33, and the amplitude of about 10-20%. Measured are time-averaged and phase-averaged velocity variations, pressure variations and temperature distributions of the flow field. Experimental conditions are identified by boundary layer measurements. Injectant behavior is characterized by the measurements of unsteady pressure in the plenum chamber and free-stream static pressure. The film cooling effectiveness is evaluated from the insulated wall temperature measurement. It has been found that bulk flow pulsation provides very large diffusion of the injectants and the effectiveness is significantly reduced by the flow pulsations.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.2
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• pp.179-184
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• 2016

The electrical load testing system developed from this study was designed to control rated-capacity-testing or variable-load-testing in an active and precise manner and save electric energy during testing, and also to convert the saved electric energy through the electrical load testing system to grid line. As for the device under testing, it was designed to be applied to not only transformer, rectifier, voltage regulator, inverter which require grid voltage source but, also applied to electric power, aerogenerator, photovoltaic, hybrid generator, battery, etc. which do not require grid voltage source. The system was designed to return the power consumed during the testing to the grid line by connecting the synchronizing pwm inverter circuit to the grid voltage source, and was also made to enable the being-tested system from disuse of approximately 93.4% energy when compared to the conventional load testing system which has used the passive resistor.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.2
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• pp.134-139
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• 2004

A clock recovery circuit for a 40 Gb/s optical receiver has been designed and implemented. The clock recovery circuit consists of pre-amplifiers, a nonlinear circuit with diodes, a bandpass filter and a clock amplifier. Before implementing the 40 Gb/s clock recovery circuit, a 10 Gb/s clock recovery circuit has been successfully implemented and tested. With the 40 Gb/s clock recovery circuit, when a 40 Gb/s signal of -10 dBm was applied to the input of the circuit, the 40 GHz clock was recovered with the -20 dBm output power after passing through the nonlinear circuit. The output signal from the nonlinear circuit passes through a narrow-band filter, and then amplified. The implemented clock recovery circuit is planned to be used for the input of a phase locked loop to further stabilize the recovered clock signal and to reduce the clock jitter.