• Journal of Powder Materials
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• v.23 no.4
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• pp.270-275
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• 2016

We report on an all-solution-processed hydrothermal method to control the morphology of ZnO nanostructures on Si substrates from three-dimensional hemispherical structures to two-dimensional thin film layers, by controlling the seed layer and the molar contents of surfactants during their primary growth. The size and the density of the seed layer, which is composed of ZnO nanodots, change with variation in the solute concentration. The ZnO nanodots act as heterogeneous nucleation sites for the main ZnO nanostructures. When the seed layer concentration is increased, the ZnO nanostructures change from a hemispherical shape to a thin film structure, formed by densely packed ZnO hemispheres. In addition, the morphology of the ZnO layer is systematically controlled by using trisodium citrate, which acts as a surfactant to enhance the lateral growth of ZnO crystals rather than a preferential one-dimensional growth along the c-direction. X-ray diffraction and energy dispersive X-ray spectroscopy results reveal that the ZnO structure is wurtzite and did not incorporate any impurities from the surfactants used in this study.

• Speech Sciences
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• v.2
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• pp.25-44
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• 1997

When listening the various speech synthesis systems developed and being used in our country, we find that though the quality of these systems has improved, they lack naturalness. Moreover, since the voice color of these systems are limited to only one recorded speech DB, it is necessary to record another speech DB to create different voice colors. 'Voice Color' is an abstract concept that characterizes voice personality. So speech synthesis systems need a voice color control function to create various voices. The aim of this study is to examine several factors of voice color control rules for the text-to-speech system which makes natural and various voice types for the sounding of synthetic speech. In order to find such rules from natural speech, glottal source parameters and frequency characteristics of the vocal tract for several voice colors have been studied. In this paper voice colors were catalogued as: deep, sonorous, thick, soft, harsh, high tone, shrill, and weak. For the voice source model, the LF-model was used and for the frequency characteristics of vocal tract, the formant frequencies, bandwidths, and amplitudes were used. These acoustic parameters were tested through multiple regression analysis to achieve the general relation between these parameters and voice colors.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.6 no.7
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• pp.37-47
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• 1995

In this paper, we have measured eletromagnetic noises from eletcric trains and the measurment data are treated statisticlly for monig. In order to measure the noise of electric tran, we set up an automatic measuring system andd measured the magnetic field over 9 kHz ~ 30 MHz range and electric field over 30 MHz - 1, 000 MHz range. The computer controlled measurint system yields efficiently experimental APD (Amplitude Probability distribution) data each of national rail road and subway train. The measured APD curves are analysed in terms of sensitivity study of Middleton's model through 6-parameter variation. Optimal parameters are obtained from measured data using Composite Approximation Algorithm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.6
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• pp.900-909
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• 1999

The receiving part of the RF system for the digital TRS base stations is developed in this paper. Based on the system specifications, the structure of the RF system is accomplished and its block diagram is drawn. The RF system is implemented according to these block diagrams. Subsequently the RF band-pass filter, the low noise amplifier, the automatic level controlled attenuator, the frequency synthesizer and other components for the system are designed and implemented, and a main board to integrate these modules is also manufactured. To lower the noise floor of the system and suppress the RF spurious noise, a PCB layout is performed carefully. For each module consisting of the RF system and the entire system, the performance tests are accomplished to check the specifications.

• Journal of the Korean Ceramic Society
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• v.32 no.7
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• pp.777-782
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• 1995

The scale up production test for the hydrothermal synthesis of clay mineral from the anorthite, which is distributed in San Chung-District of Korea and called as the ground rock for halloysite-kaolin, has been investigated by using the gaitator type reactor. The automatic control system has been developed and applied for the more effective producibility and the reduction in the defect of this intermittent batch processing property, and finally for the feasibility of this system in actual use. It was observed that this agitator type reactor can reduce the synthesis reaction tme from 5 days to 3 days, only with the condition of 20rpm. The automatic control system could regulate the vessel temperature and pressure precisely at an optimum condition during the treatment. Therefore, from these test results the application-possibility for this system was found to be feasible in actual use.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.649-652
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• 2013

LEON3 is a 32-bit synthesisable processor based on the SPARC V8. It can be connected to AMBA 2.0 bus and has a 7-stage pipeline, IEEE-754 FPU and 256[KB] cache. It can be easily implemented using FPGA and used for a SoC design. DSU which comes with LEON3 can be used to control and monitor the operation of LEON3. And DSU makes it easy to set a debugging environment for the development of both hardware and software for an embedded systems based on LEON3. This paper presents the summary of the development of LEON3 monitoring software.

• The Transactions of the Korea Information Processing Society
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• v.5 no.1
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• pp.119-127
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• 1998

In this paper, the design of a VLSI-based multilayer neural network is presented, which can be used as a dedicated hardware for character-type segmentation and character-element recogniti on consuming large processing time in conventional software-based Hangul printed-character recognition systems. Also the architecture and its design of a neural coprocessor interfacing the neural network with a host computcr and controlling thc neural network are presented. The architecture, behavior, and performance of the proposed neural coprocessor are justified using VHDL modeling and simulation. Experimental results show the successful rates of character-type segmentation and character-element recognition is competitive to those of software-based Hangul printed-character recognition systems with retaining high-speed.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.116.2-116.2
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• 2016

n-type 반도체의 성질을 가지고 있는 $TiO_2$는 화학적 안정성, 3.2 eV의 밴드갭 에너지 등에 의하여 다양한 형태의 에너지 변환 및 저장 소재로 많이 연구되어지고 있다. 특히, Fujishima-Honda의 발견에 의한 광촉매적 특성은 $TiO_2$의 가장 대표적인 응용 분야라 할 수 있다. 이런 $TiO_2$는 솔-겔, 수열합성법, 침전법 등의 화학적 방법을 통하여 제조 한다. 하지만 이런 방법은 $TiO_2$를 전극으로 사용하기 위한 추가적인 공정이 필수적일 뿐 아니라 그 구조를 제어하기가 쉽지 않다. 이에 약 10여 년 전부터 많은 연구자, 과학자들은 금속 기판위에 $TiO_2$를 형성하는 양극산화 법에 대한 관심을 가지고 꾸준히 연구되어져 왔다. 양극산화법을 통한 $TiO_2$는 그 조건에 따라 박막, 기공(포어)구조, 튜브 구조 및 다양한 나노 구조를 형성할 수 있게 한다. 그렇지만 대표적인 구조는 기공간의 공간을 유지하는 나노 튜브의 형태라 할 수 있다. $TiO_2$ 나노 튜브를 형성하기 위해서는 극미량의 fluoride 이온이 첨가된 전해질에서 이루어진다고 알려져 왔다. 본 발표에서는 이런 전해질의 조건에 따른 나노튜브 구조의 변화를 보고 그 변화에 따른 광전기화학적 차이점에 대하여 논하고자 한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.05c
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• pp.2149-2152
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• 2003

전자상거래에 관련된 데이터 교환이 인터넷 상에서 쉽고 원활하게 이루어질 수 있도록 하는 어플리케이션에 적합한 언어로 평가받고 있는 XML은 문서의 데이터 포맷 표현을 향상시키는데 중점을 두고 만들어졌기 때문에 문서 변조 및 데이터 삭제 등의 공격에 취약한 문제점을 가지고 있다 이러한 문제점에 대한 해결책으로 XML 전자 서명, XML 암호화 기법, XML 접근 제어와 같은 다양한 해결책이 제시되었지만 XML 암호화로 인한 구조적인 XML 유효성 위반 문제 및 DTD 공격에 대한 해결책 부재 등의 문제점이 해결되지 않고 있다. 본 연구에서는 XML 문서에만 전자서명을 첨부하는 것이 아니라. DTD에 전자 서명을 첨부하는 방법을 제안하였다. 먼저 DTD파일을 끝까지 읽으면서 파싱을 하고 여기서 추출되는 엘리먼트나 속성, 엔티티들을 해시테이블에 저장한다. 파싱이 종료되면 해시 테이블을 읽어 들여서 메시지 다이제스트를 수행한다. 수행 후 이를 개인 키와 합성하여 전자 서명을 생성한다.

• Journal of the Korean Institute of Telematics and Electronics
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• v.17 no.5
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• pp.48-55
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• 1980

For the purpose of composing an anti-ghost antenna system, 2 antennas, which have the identical radiation pattern, are fixed parallel to each other with a constant separation. In view of the fact that the phase differnce between the added power and the subtracted power of the two undesired signal which is recieved from all direction except from the real front one becomes radian, now It is Possible to make the amplitude of each Power become equal and the phase of the subtracted power become out of phase with that of the added power, by adjusting the amplitude of the subtracted power and shifting its phase by + or radian. Therefore the sum of the added power and the above modified subtracted power will be able to become zero. According to the above study, a hybrid circuit is designed and through operation of this circuit , the undesired wave can be seen to be reduced by 20 dB.