• 한국군사과학기술학회지
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• 제2권2호
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• pp.30-39
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• 1999

In this paper, we have proposed a novel method which can compose a reflected signal of the underwater target. The synthesis of the reflected signal in the target, the synthesized signal being similar to the characteristics of the reflected signal in the real target, is used the highlight model at the specific points of the target. We suggest the synthesis method of the reflected signal of the target using the pulsewidth variation and each other doppler effect at the highlight point, and compare the composed signal by the proposed method with that by conventional one. Simulation results show that the composed signal using the proposed method and the reflected signal of the real target is similar to the spectral characteristics.

• 음성과학
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• 제4권1호
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• pp.19-34
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• 1998

The author collected and compared midsagittal, coronal, coronal oblique, and transversal images of Korean monophthongs /a, i, e, o, u, i, v/ produced by a healthy male speaker using 1.5 T MR, VISION. Area was measured by computer software after tracing the cross-section at different points along the tract. Results showed that the width of the oral and pharyngeal cavities varied compensatorily from each other on the midsagittal dimension. Formant frequency values estimated from the area functions of the seven vowels showed a strong correlation (r=0.978) with those analyzed from the spoken vowels. Moreover, almost all of 35 students who listened to the synthesized vowels from area data perceived the synthesized vowels as equivalent to the spoken ones. Movement of constriction points of vowel /u/ with wider lip opening sounded /i/ and led to slight changes in vowel quality. Jaw and tongue movement led to major volume variation with an anatomical limitation. Each comer vowel varied systematically from a somewhat constant volume of the average area. Thus, the author proposed that any simulation studies related to vocal tract area variation should reflect its constant volume. The results may be helpful to verify exact measurement of the vocal tract area through vowel synthesis and a simulation study before having any operation of the vocal tract.

• Bulletin of the Korean Chemical Society
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• 제12권6호
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• pp.666-673
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• 1991

The elongation of the chain length at 2'position of aminothiazolylacetamido group of cephalosporin antibiotics was achieved. The derivatives with elongated side chain at 2'position were successfully synthesis and their in vitro activities were evaluated. It is indicated that there is an optimum range of the chain length in order to exhibit higher biological activities. This result could open a possibility for the development of the cephalosporin antibiotics with higher activities by further variation of the substituents at other positions. The cephalosporin derivatives with a simple (relatively non-functionalized) side chain as well as with a linear extended side chain were also prepared. Low activities of these derivatives led to a conclusion that either simple (non-functionalized) change or linear elongation of the side chain does not enhance the antibacterial activities.

• 한국정보처리학회논문지
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• 제5권3호
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• pp.851-861
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• 1998

한국어는 음운 변동 현상이 매우 발달되어 있다는 특징을 갖고 있다. 따라서, 음성 인식율의 제고와 음성 합성음의 자연스러움을 향상시키기 위해서는 음운 변동 현상을 비롯한 한국어의 모든 특징에 대한 체계적인 연구가 있어야 한다. 본 논문은 한국어의 제 특징 중에서 음운 변동 현상을 효율적으로 처리할 수 있는 규칙을 설계하고 구현함으로써, 한국어 음성 인식과 합성에 효율적으로 이용될 수 있음을 보인다. 음운 변동 규칙의 설계를 위하여 사용된 규정은 한글 맞춤법 통일안의 표준 발음법(7장 30항)이며, 일차적으로 각 규정별로 설계된 규칙을 최종적으로 27개 그룹으로 정리된 종성별 규칙을 제시하였다. 본 연구에서 제안된 음운 변동 처리 시스템은 한번의 규칙 적용으로 음운 변도 dgus상이 신속히 처리되는 잇점이 있으며, 단어 및 용언의 어간에 접속되는 정보에 대한 처리 내용까지도 제안된 규칙내에 수용하였기 때문에 문장 단위의 음성 인식과 합성 시스템의 연구에 도움을 줄 수 있다.

• 한국컴퓨터그래픽스학회논문지
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• 제15권1호
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• pp.17-23
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• 2009

본 논문에서는 다수의 회전 이미지를 생성, 이용해 결과의 다양성을 추구하고 기존 기법들의 문제인 예제 가장자리 경계면의 Neighborhood를 이용해 생기는 경계선을 완화한 합성 결과물을 생성하는 새 예제 기반 텍스처 합성 방법을 제안한다. 논문에서 제안하는 방법은 구현하기에 따라 공간 결정적인 형태로 구축할 수 있으며 병렬 처리가 가능한 하드웨어를 이용한 병렬 연산처리로 합성 속도 가속을 하는데도 유리한 구조를 가지고 있다.

• The Korean Journal of Ceramics
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• 제2권4호
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• pp.221-225
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• 1996

In diamond synthesis by metal film growth method under high pressure and high temperature, the nucleation and growth of diamond was observed dependent on the carbon source variation from graphite powder to the heat treated powders of lamp black carbon. At the low driving force condition near equilibrium pressure and temperature line, nucleation of diamond did not occur but growth of seed diamond appeared in the synthesis from lamp black carbon while both nucleation and growth of diamond took place in the synthesis from graphite. Growth morphology change of diamond occurred from cubo-octahedron to octahedron in the synthesis from graphite but very irregular growth of seed diamond occurred in the synthesis from lamp block carbon. Lamp black carbon transformed to recrystallized graphite first and very nucleation of diamond was observed on the recrystallized graphite surface. Growth morphology of diamond on the recrystallized graphite was clear cubo-octahedron even at higher pressure departure condition from equilibrium pressure and temperature line.

• 음성과학
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• 제8권1호
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• pp.7-19
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• 2001

The acoustic parameters of nine Korean numbers were analyzed by Praat, a speech analysis software, and synthesized by SenSynPPC, a Klatt formant synthesizer. The overall intensity, pitch and formant values of the numbers were modified dynamically by a step of 1 dB, 1 Hz and 2.5% respectively. The study explored the sensitivity of listeners to changes in the three acoustic parameters. Twelve subjects (male and female) listened to 390 pairs of synthesized numbers and judged whether the given pair sounded the same or different. Results showed that subjects perceived the same sound quality within the range of 6.6 dB of intensity variation, 10.5 Hz of pitch variation and 5.9% of the first three formant variations. The male and female groups showed almost the same perceptual ranges. Also, an asymmetrical structure of high and low boundary was observed. The ranges may be applicable to the development of a speaker identification system while the method of synthesis modification may apply to its evaluation data.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계학술대회 논문집 디스플레이 광소자 분야
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• pp.61-64
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• 2002

A novel ceramic synthesis technique, combustion synthesis, is explored to produce a orange-emitting $SnO_{2}:Eu^{3+}$ phosphors. This technique involves a reaction of metal salts with a citric acid as an organic fuel. The variation of the ratio of citric acid to metal introduces change in reaction temperature and atmosphere of the combustion reaction, which in turn influences crystallinity and luminescence properties of the final products seriously. And, the heat treatment of the as-synthesized product increases its luminescence intensity. Especially, the samples treated at above $1100^{\circ}C$ show a orange-emission peak, which is attributed to the formation of single phase and well-crystallized $SnO_{2}:Eu$ oxides in the rutile structure

• 한국재료학회:학술대회논문집
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• 한국재료학회 2010년도 춘계학술발표대회
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• pp.11.1-11.1
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• 2010

As one of the non-vacuum, low temperature fabrication route, electrochemical synthesis has been focused for pursuing the cost-effective pathway to produce high efficiency photovoltaic devices. Especially the availability to form the thin film structure on flexible substrate would be the great advantage of electrochemical process. The successful synthesis of the most favorable absorber materials such as CdTe and CIGS has been reported by many researchers, however, the efficiency of electrochemically synthesized could not exceed that from vacuum process, because of microstructural controllability and compositional variation on devices. In this study, we represent the effect of process parameters on the microstructure and composition of compound semiconductor during the synthesis, and propose the photovoltaic characteristics of electrochemically synthesized solar cells.

• 한국세라믹학회지
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• 제32권9호
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• pp.1085-1091
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• 1995

Molybdenum disilicide (MoSi2) was synthesized from Mo, MoO3, Si and Al powders by self-propagating high temperature synthesis (SHS). The effect of processing parameters such as Mo/MoO3 molar ratio, Ar gas pressure in the reactor and pressing pressure of compacts in synthesis of MoSi2 were investigated. h-MoSi2 was transformed into t-MoSi2 with increasing the Mo/MoO3 mole ratio, and only t-MoSi2 phase was identified above 3.5 : 1 (molar ratio). The synthesized phases did not change with the variation of Ar gas pressure and pressing pressure of compacts. It was found that the combustion temperature was above 2,50$0^{\circ}C$. The products were separated into MoSi2 (s) and $\alpha$-Al2O3 by the difference of their specific grativities. Bending strength, hardness and density of sintered specimen exhibited 82 MPa, 5.368 GPa and 5.43 g/㎤, respectively.