• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.4
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• pp.612-619
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• 1990

In this paper, a design method of optical FSK transmitter is described using LD-FM circuit model. In the design of optical FSK transmitter, an optimum bias current was chosen using LD-FM circuit model, and an unequalized FM transfer function was determined at this current. The equalizers that can make this transfer function uniform were designed by use of a simple passive network. For the designed optical FSK transmitter, the pulse-transient and small-signal frequency-deviation responses were simulated and discussed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.8
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• pp.714-720
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• 2009

In this paper, design and the implementation method of a band-tunable ultra-wideband planar doubler are described Microstrip-to-CPS(balun) transition and Microstrip-to-CPW transition are respectively used for input/output matching circuits for the doubler. The Input balun structure allows to apply diode bias, and the doubler output frequency is tunable by changing the diode bias voltage. With the bias voltage of -0.6 V, the measured operating frequency band of the implemented doubler is $10{\sim}20$ GHz, with the bias voltage of $-0.2{\sim}-0.4$ V, the operating frequency band is $10{\sim}30$ GHz, and with 0 V bias, the operating frequency band is $20{\sim}30$ GHz. The doubler provides conversion loss of less than 15 dB and fundamental frequency suppression of 30 dB.

• Survey Research
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• v.12 no.3
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• pp.49-62
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• 2011

In this paper we investigate design-based properties of both the ordinary least square estimator and the weighted least square estimator for regression coefficients in panel regression model. We derive formulas of approximate bias, variance and mean square error for the ordinary least square estimator and approximate variance for the weighted least square estimator after linearization of least square estimators. Also we compare their magnitudes each other numerically through a simulation study. We consider a three years data of Korean Welfare Panel Study as a finite population and take household income as a dependent variable and choose 7 exploratory variables related household as independent variables in panel regression model. Then we calculate approximate bias, variance, mean square error for the ordinary least square estimator and approximate variance for the weighted least square estimator based on several sample sizes from 50 to 1,000 by 50. Through the simulation study we found some tendencies as follows. First, the mean square error of the ordinary least square estimator is getting larger than the variance of the weighted least square estimator as sample sizes increase. Next, the magnitude of mean square error of the ordinary least square estimator is depending on the magnitude of the bias of the estimator, which is large when the bias is large. Finally, with regard to approximate variance, variances of the ordinary least square estimator are smaller than those of the weighted least square estimator in many cases in the simulation.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2000.11a
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• pp.257-266
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• 2000

산업 및 가정용 기기들이 점차 복잡해짐에 따라 다양한 공학 분야의 해석 기술을 동시에 고려하면서 이들 원리를 적용한 최적의 설계를 결정하는 방법론의 필요성이 대두되고 있다. 다분야통합최적설계 또는 MDO(Multidisciplinary Design Optimization)라 일컫는 새로운 기술은 이러한 필요에 대응하는 기술로서 국내외적으로 활발한 연구가 진행되고 있다. 이러한 MDO 기술을 구현하는 소프트웨어와 하드웨어 복합 체계를 MDO 프레임웍(framework)이라 한다. 일반적으로 프레임웍이란 실제 응용프로그램의 용도에 맞는 주문제작(customization)이 가능한 일종의 전단계 프로그램이라 할 수 있다 MDO 프레임웍은 설계 및 해석 도구들간의 인터페이스를 제공하고, 이들 도구들이 사용하는 설계 데이터를 효율적으로 공유할 수 있도록 지원하여, 설계 작업을 정의, 실행, 관리하는 역할을 한다. 이러한 MDO 프레임웍은 설계 작업을 통합적으로 관리하고 자동화하여 설계 도구간의 데이터 전달과 변환에 소묘되는 설계자의 부담을 경감시키며 다분야 전문가가 참여하는 공통 작업 환경을 제공함으로써 설계 효율성을 증진시킨다. 본 논문에서는 이러한 효용을 달성하기 위한 MDO 프레임웍(framework)을 제시하고 프레임웍 설계의 논리적 근저와 타당성을 밝힌다. 본 논문에서 제안하는 다분야 통합 최적화를 위한 분산형 지능 시스템인 DisMDO는 사용자가 GUI를 동해서 편리하게 다분야통합최적화 문제를 해결할 수 있도록 지원하며, 제공되는 스크립트 언어를 동해서도 이를 정의할 수 있도록 지원하여 일괄처리도 가능하도록 한다. 또한, 집중화된 데이터베이스를 관리하여 다분야 전문가들이 공통의 데이터를 안전하게 공유할 수 있도록 지원하며, 외부에서 제공되는 해석 도구나 최적화 모듈을 손쉽게 프레임웍에 통합시킬 수 있도록 하는 인터페이스 제작기(factory) 기능을 제공한다.ackscattering spectroscopy, X-ray diffraction, secondary electron microscopy, atomic force microscoy, $\alpha$-step, Raman scattering spectroscopu, Fourier transform infrared spectroscopy 및 micro hardness tester를 이용하여 기판 bias 전압이 DLC 박막의 특성에 미치는 영향을 조사하였다. 분석결과 본 연구에서 제작된 DLC 박막은 탄소와 수소만으로 구성되어 있으며, 비정질 상태임을 알 수 있었다. 기판 bias 전압의 증가에 따라 박막의 두께가 감소됨을 알 수 있었고, -150V에서는 박막이 거의 만들어지지 않았으며, -200V에서는 기판 표면이 식각되었다. 이것은 기판 bias 전압과 ECR 플라즈마에 의한 이온충돌 효과 때문으로 판단되며, 150V 이하에서는 증착되는 양보다 re-sputtering 되는 양이 더 많을 것으로 생각된다. 기판 bias 전압을 증가시킬수록 플라즈마에 의한 이온충돌 현상이 두드러져 탄소와 결합하고 있던 수소원자들이 떨어져 나가는 탈수소화 (dehydrogenation) 현상을 확인할 수 있었으며, 이것은 C-H 결합에너지가 C-C 결합이나 C=C 결합보다 약하여 수소 원자가 비교적 해리가 잘되므로 이러한 현상이 일어난다고 판단된다. 결합이 끊어진 탄소 원자들은 다른 탄소원자들과 결합하여 3차원적 cross-link를 형성시켜 나가면서 내부 압축응력을 증가시키는 것으로 알려져 있으며, hardness 시험 결과로 이것을 확인할 수 있었다. 그리고 표면거칠기는 기판 bias 전압을 증가시킬수록 더 smooth 해짐을 확인하였다.인하였다.을 알 수 있었다. 즉 계면에서의 반응에 의해 편석되는 Ga에 의해 박막의 strain이 이완되면, pinhole 등의 박막결함

• The Journal of Information Systems
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• v.24 no.2
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• pp.189-208
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• 2015

Purpose While individuals have unique abilities for planned behavior, they also often act irrationally. In this study, we draw on myopic loss aversion perspective as a meta-theoretical lens to explain why mobile applications users have inertia from updating their applications, ultimately leading them to use current version of applications. Design/methodology/approach Based on a survey of 219 users, this study conducts its research model using partial least square analysis and also demonstrates that both subconscious triggers (habit and anxiety) of system 1 thinking and conscious triggers (sunk cost and transition cost) of system 2 thinking promotes user's inertia, thus leading to the willness to continue use current versions. Findings By grounding the research model in the combination of both status quo bias and dual information processing theory from the behavioral economics, this study provide an alternative theoretical lens to describe why mobile users hesitate to update their applications. The results of this research show that all triggers have significant impacts on inertia. This study also found that the relationship between inertia and willingness to continue to use current version was positively significant.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.7
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• pp.28-38
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• 1997

Previously, we have proposed the M-BECM(Modified-Band Edge Component Maximization), which is a symbol synchronization algorithm based on spectral line method for all-digital high speed digital communications. However, Until now, the characteristics of the timing detector based on the spectral line method including M-BECM was not analyzed, particularly the effect of a timing offset at the optimal convergence pont. In this paper, we analyze the timing dtector's characteristics of the M-BECM and present optimal design value. First, the expression for the timing detector's mean value(often called its S-Curver) as a function of the normalized symbol timing offset is derived. Next, the P $D_{bias}$, the value for compensating the timing offset at an optimal convergence point, and the bandwidth of bandpass filter in the timing detector are calculated. It is also shown and analyzed that the P $D_{bias}$ is affected by varuous factors such as the excess bandwidth of input signal, frequency offsets, noise and particularly, the excess bandwidth of input signal is a major parameter to decide P $D_{bias}$. Finally, analytic resutls are compared to simulation results.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.261-264
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• 2005

This paper presents the design of a down-conversion mixer with built-in active balun integrated in a $0.25\;{\mu}m$ pHEMT process. The active balun consists of series-connected common-gate FET and common-source FET. The designed balun achieved broadband characteristics by optimizing gate-width and bias condition for the reduction in parasitic effect. From DC to more than 6GHz, the active balun shows the phase error of less than 3 degree and the gain error of less than 0.4 dB. A single-balanced down-conversion mixer with built-in broadband active balun has been designed with optimum width, load resistor and bias for conversion gain and without any matching component for broadband operating. The designed mixer whose size of including on-chip bias circuit is $1\;mm{\times}1\;mm$ shows the conversion gain of better than 7 dB from 2 GHz to 6 GHz and $P_{1dB}$ of -10 dBm at 5.8 GHz

• JSTS:Journal of Semiconductor Technology and Science
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• v.9 no.4
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• pp.192-197
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• 2009

This paper presents the design and measurement of a 2.4/5.2-GHz dual band VCO with a balanced frequency doubler in $0.18\;{\mu}m$ CMOS process. The topology of a 2.4 GHz VCO is a cross-coupled VCO with a LC tank and the frequency of the VCO is doubled by a frequency balanced doubler for a 5.2 GHz VCO. The gate bias matching network for class B operation in the balanced doubler is adopted to obtain as much power at 2nd harmonic output as possible. The average output powers of the 2.4 GHz and 5.2 GHz VCOs are -12 dBm and -13 dBm, respectively, the doubled VCO has fundamental harmonic suppression of -25 dB. The measured phase noises at 5 MHz frequency offset are -123 dBc /Hz from 2.6 GHz and -118 dBc /Hz from 5.1 GHz. The total size of the dual band VCO is $1.0\;mm{\times}0.9\;mm$ including pads.

• Journal of Oriental Neuropsychiatry
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• v.28 no.3
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• pp.165-182
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• 2017

Objectives: The purpose of this systematic review was to understand clinical usefulness of Emotional Freedom Techniques (EFT) on students' mental health. Methods: Ten databases were included to extract clinical studies on effects of EFT intervention with students. Characteristics of selected studies were described, and biases were assessed with Risk of Bias (RoB) or Risk of Bias Assessment for Non-Randomized Studies (RoBANS). Results: A total of 14 clinical trials were extracted for analysis. There were 8 randomized-controlled trials (RCTs), 2 non-randomized-controlled trials (nRCTs), and 4 before-after studies. EFT have significant clinical usefulness in public speaking anxiety, test anxiety, stress, depression, learning related emotions, adolescent anxiety, and eating issues. The risk of selection bias in most studies was high or uncertain. Conclusions: EFT is an effective clinical technique for managing students' mental health issues. However, the included studies have been conducted with relatively poor quality and small sample size. Clinical trials with high quality study design and well-designed EFT education programs are needed to generalize clinical usefulness.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.8 no.1
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• pp.12-17
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• 2009

In this paper, We play it for the purpose of study about the power amplifier which applied DGS and adaptive bias circuit structure to general Doherty amplifier for the efficiency of a RF power amplifier and a linearity improvement in the WiBro band. As for the IMD3, 3.4dBc was improved with -26.3dBc when we did the measurement result existing Doherty power amplifier and comparison of the Doherty power amplifier which applied an adaptive bias circuit and the DGS which proposed in this paper, and the mean power efficiency verified what was increased in 37%. Also, we were able to know PAE of 36.6% with output power 34.0dBm in P1dB when magnitude of an input signal was 25.6dBm. we did 6dB back off in output P1dB in order to confirm the ACPR which was a nonlinear characteristic and measured the ACPR. we showed the -34.55dBc which was a value of -34.5dBc or below in the 4.77MHz off-set that was a transmission standard. Therefore, we were able to know that we were satisfied with a spectrum mask standard.