• Transactions on Electrical and Electronic Materials
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• v.7 no.4
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• pp.173-179
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• 2006

Due to the limitations of the channel length, the lateral spread for two-dimensional impurity distributions is critical for the analysis of devices including the integrated complementary metal oxide semiconductor (CMOS) circuits and high frequency semiconductor devices. The developed codes were then compared with the two-dimensional implanted profiles measured by transmission electron microscope (TEM) as well as simulated by a commercial TSUPREM4 for verification purposes. The measured two-dimensional TEM data obtained by chemical etching-method was consistent with the results of the developed analytical model, and it seemed to be more accurate than the results attained by a commercial TSUPREM4. The developed codes can be applied on a wider energy range $(1KeV{\sim}30MeV)$ than a commercial TSUPREM4 of which the maximum energy range cannot exceed 1MeV for the limited doping elements. Moreover, it is not only limited to diffusion process but also can be applied to implantation due to the sloped and nano scale structure of the mask.

• Proceedings of the KIEE Conference
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• 1994.11a
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• pp.382-384
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• 1994

Wireless communication has become a hot issue for its simplicity. Using light wave instead of micro wave has many advantages. It is simple to design a circuit because we can make a circuit with discrete components such as photo diode, photo detector, OP Amp[2]. And we can have many communication channels for we can use every frequency domain. In this paper, we design the wireless communication system and analyze the pulse signal. Then using ray tracing technology we simulate the distribution of light beam.

• Korean Membrane Journal
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• v.3 no.1
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• pp.59-68
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• 2001

Unlike existent field flow fractionation, new method, osmotic sink field flow fractionation is introduced and used ultrafiltration hollow fiber membranes as separation channel. This hollow fiber osmotic sink field flow fractionation is called HF-OSFFF. A theory that describes the retention, relaxation, resolution, plate number for the system, has been developed and experimentally verified by separation model of po1ystyrene latex beads. At external field, it is measured that radial flow rates change according to various concentrations of PEG solutions. Concentration of PEG solution vs. radial flow rate is a linear relation. For diameter distribution of unknown polymer sample, HF-OSFFF compared with the commercial capillary hydrodynamic flow fractionation (CHDF).

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.1
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• pp.46-55
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• 2004

Thermal characteristics of the various cooling methods in electronic equipment are studied numerically. A common chip cooling system is modeled as a parallel channel with protruding heat sources. A two-dimensional model has been developed for the numerical analysis of compressible. viscous. laminar flow. and conjugate heat transfer between parallel plates with uniform block heat sources. The finite volume method is used to solve this problem. The assembly consists of two channels formed by two covers and one printed circuit board that is assumed to have three uniform heat source blocks. Various cooling methods are considered to find out the efficient cooling method in a given geometry and heat sources. The velocity and the temperature fields. the local temperature distribution along the surface of blocks. and the maximum temperature in each block are obtained. The results are compared to examine the thermal characteristics of the different cooling methods both quantitatively and qualitatively.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.8
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• pp.8-16
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• 1999

In this paper, the performance of a hybrid DS/SFH-SS(direct-sequence/slow-frequency-hopped spread-spectrum) system with coherent BPSK modulation over Nakagami fading channel in the presence of multiple tone jamming is analyzed. Because the Nakagami m-distribution can describe not only Rayleigh fading but also more general fluctuations involving a specular component by adjusting the value of the fading index m. It is known that for m=1 corresponds to Rayleigh fading, for $1/2{\le}m{\le}1$ corresponds to the worst case fading condition, for m>1 corresponds to Rician fading, and for $m{\to}{\infty}$ corresponds to the nonfading condition. The bit error probability is derived over Nakagami model and numerical evaluations are presented for some combinations of system parameters. The results show that as m increases, the bit error probability is better. Also, at a low JSR(jamming-to-signal power ratio), a pure DS-SS system can achieve lower bit error probability than a hybrid DS/SFH-SS system. But at a high JSR, a hybrid DS/SFH-SS system is shown to be superior to a pure DS-SS system. Therefore, it is demonstrated that without increasing the total system bandwidth, the performance of a hybrid DS/SFH-SS is superior to that of a pure DS-SS system in the presence of multiple tone jamming.

• Journal of Distribution Research
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• v.11 no.2
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• pp.29-57
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• 2006

While a number of studies have recognized the importance of environment of channel systems and consequences of changed environment, only limited studies have dealt with this issue theoretically and practically. The purpose of this study is to empirically validate whether one dimension of environment, called dynamism, has an influence on the relationship characteristics such as transaction specific investment opportunism and conflict or not: further, it is designed to delve into whether these relationship characteristics have any influence on one crucial relationship quality, 'trust' and its two constituent dimensions - credibility and benevolence. In order to provide empirical validation, a survey was conducted to 163 sales office managers at a major newspaper publisher in Korea. An analysis of the data retrieved from this survey indicated that while environmental dynamism has a positive influence on the publisher's opportunism and conflict perceived by the sales office managers, it did not show a direct influence on the transaction specific investment made by the publisher. Furthermore, while publisher's transaction specific investment had a positive influence on the credibility and the benevolence respectively, publisher's opportunism and level of sales office conflict had a negative influence on the credibility and the benevolence respectively. Currently, a publisher is facing an unprecedentedly dynamic environment. This study should provide ample implications for the publisher in establishing trust, which is a crucial condition in developing and maintaining a long-term successful relationship with its sales offices.

• Journal of Distribution Research
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• v.16 no.5
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• pp.19-41
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• 2011

Home shopping is called the flower of future distribution. Among them, for TV home shopping, Korea should lead the industry as an advanced country in IT technology. It is difficult for small and medium businesses, however. This is due to the failure of the policies of Korea Communications Commission. In order to complement such policy failure, this study intends to analyze the preceding domestic studies and foreign status, and reflect such on the policy. Especially the domestic business will be predicted through foreign home shopping status and policy cases, and the items that should be supplemented with governmental policy in order to vitalize small & medium businesses were analyzed; these should be actively reflected by the government. In case of general PP, it already runs on the registration system, and the home shopping channel should also be the same and be committed to the market. The increased number of channels would allow a greater opportunity for small and medium businesses who are the suppliers, and for the consumers, the product prices would be able to be stabilized at an appropriate cost and high quality and diversity of items could be obtained through home shopping, thus improving consumer welfare. If it is difficult to adopt the registration system for home shopping right away, the best alternative is to strengthen the approval system. As home shopping requires a re-approval every 3 years, strengthened re-approval conditions would resolve part of the problem.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.9
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• pp.817-825
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• 2013

The UHDTV system, which provides realistic service with ultra-high definite video and multi-channel audio, has been studied as a next generation broadcasting service. Since the conventional digital terrestrial transmission system is not capable to cover the increased transmission data rate of the UHDTV service, there are great necessity of researches about increase of data rate. Accordingly, the researches has been studied to increase the transmission data rate of the DVB-T2 system using dual-polarized MIMO technique and high order modulation. In order to optimize the MIMO DVB-T2 system where irregular LDPC codes are used, it is necessary to study the design of the bit mapper that matches the LDPC code and QAM symbols in MIMO channel. However, the research related to the design of the bit mapper has been limited to the SISO system. Therefore, this paper defines a new parameter that indicates the VND distribution of MIMO DVB-T2 system and performs the performance analysis according to the parameter which will be helpful for designing a MIMO bit mapper.

• ETRI Journal
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• v.36 no.2
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• pp.214-223
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• 2014

A fully-integrated penta-band reconfigurable power amplifier (PA) is developed for handset Tx applications. The output structure of the proposed PA is composed of the fixed output matching network, power and frequency reconfigurable networks, and post-PA distribution switches. In this work, a new reconfiguration technique is proposed for a specific band requiring power and frequency reconfiguration simultaneously. The design parameters for the proposed reconfiguration are newly derived and applied to the PA. To reduce the module size, the switches of reconfigurable output networks and post-PA switches are integrated into a single IC using a $0.18{\mu}m$ silicon-on-insulator CMOS process, and a compact size of $5mm{\times}5mm$ is thus achieved. The fabricated W-CDMA PA module shows adjacent channel leakage ratios better than -39 dBc up to the rated linear power and power-added efficiencies of higher than around 38% at the maximum linear output power over all the bands. Efficiency degradation is limited to 2.5% to 3% compared to the single-band reference PA.

• Journal of Broadcast Engineering
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• v.6 no.1
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• pp.13-20
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• 2001

In this paper, we propose a new digital audio watermarking scheme In the cepstrum domain. We insert a digital watermark signal Into the cepstral components of the audio signal using a technique analogous to spread spectrum Communications, hiding a narrow band signal in a wade band channel. In our proposed method, we use pseudo-random sequences to watermark the audio signal. The watermark Is then weighted in the cepstrum domain according to the distribution of cepstral coefficients and the frequency masking characteristics of the human auditory system. The proposed watermark embedding scheme minimizes audibility of the watermark signal. and the embedded watermark is robust to mu1tip1e watermarks, MPEG audio ceding and additive noose.