• International Journal of Advanced Culture Technology
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• 제10권4호
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• pp.460-469
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• 2022

Increasing interest in the metaverse world these days, interest in realistic content such as 3D displays is growing. In particular, hologram images seen in movies provide viewers with an immersive display that cannot be seen in conventional 2D images. Since the first discovery of holography by Dennis Gabor in 1948, this technology has developed rapidly. Spatially, this beginning of technology like Optical hologram called analog hologram and Digital hologram such as computer-generated hologram (CGH). In analog and digital holograms, a recording angle and a recording wavelength are having important role when reproducing and display hologram. In the hologram, diffraction of light causes by unexpected formed by the synthesis from interference with object and reference light. When recording, the incident light information and mismatched reproduction light reconstruct the hologram in an undesirable direction. Reproduction light that is out of sync with incident light information with initial condition of recording will cause reconstructed image in an undesirable direction. Therefore, we analyze the holographic interference pattern generated by hologram recording in volume holograms using photopolymer and analyze the characteristics that vary depending on the angle of the reproduced light. This is expected to be used as a basic research on various holographic application that may cause as holograms are applied to industries in the future.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 추계종합학술대회 논문집(3)
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• pp.149-152
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• 2000

We propose simple analog MOS circuits producing the one-dimensional compact motion-sensing circuits. In the proposed circuit, the optical flow is computed by a number of local motion sensors which are based on biological motion detectors. Mimicking the structure of biological motion detectors made the circuit structure quite simple, compared with conventional velocity sensing circuits. Extensive simulation results by a simulation program of integrated circuit emphasis (SPICE) indicated that the proposed circuits could compute local velocities of a moving light spot and showed direction selectivity for the moving spot

• Bulletin of the Korean Chemical Society
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• 제34권11호
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• pp.3372-3376
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• 2013

The kinetic studies on the reactions of ethyl methyl (2) and ethyl propyl (4) chlorothiophosphates with X-pyridines have been carried out in acetonitrile at $35.0^{\circ}C$. The free energy correlations with X show biphasic concave upwards with a break point at X = H (2) and 3-Ph (4), respectively. A stepwise mechanism with a rate-limiting leaving group expulsion from the intermediate is proposed based on the magnitudes of selectivity parameters for both substrates. The considerably large values of ${\beta}_X$ = 1.50(2) and 1.44(4) with strongly basic pyridines and relatively small values of ${\beta}_X$ = 0.43(2) and 0.36(4) with weakly basic pyridines are interpreted as a change of the attacking direction of the X-pyridines from a frontside to a backside attack toward the chloride leaving group.

• Bulletin of the Korean Chemical Society
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• 제23권8호
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• pp.1103-1105
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• 2002

H-ZSM-5 and γ-alumina were treated with formaldehyde and sodium carbonate. The treatment increased the amounts of weak acid sites, removing strong acid sites. The maximum temperature of weak acid sites in their ammonia TPD spectra shifted in the direction of high temperature. The modified H-ZSM-5 and g-alumina were mixed with the methanol synthesis catalyst to perform dimethyl ether synthesis from syn-gas. The modified catalysts showed better selectivity to dimethyl ether, minimizing the reforming reaction to carbon dioxide. The maximum yield of 53.3% to dimethyl ether was achieved under the reaction conditions of 54.4 atm, 523 K, and the feed rate of 4500 Lhr-1 .gcat-1.

• Bulletin of the Korean Chemical Society
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• 제19권8호
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• pp.840-846
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• 1998

The mechanism by which pyrrhotite is depressed by diethylenetriamine (DETA) during pentlandite flotation has been studied. Amyl xanthate is observed to adsorb on pyrrhotite to form both dixanthogen and iron xanthate. In the presence of DETA, the amount of xanthate adsorbed on pyrrhotite is substantially reduced as evidenced by infrared and UV/Vis spectroscopy. However, DETA does not adsorb on pyrrhotite as evidenced by infrared and X-ray photoelectron spectroscopy. DETA shifts the potential of the onset of xanthate adsorption on pyrrhotite by approximately 200 mV toward anodic direction, which is thought to be due to the increased solubility of surface oxidized species on pyrrhotite in the presence of DETA. A window of selectivity for the separation of pentlandite and pyrrhotite is provided by the results obtained in this study.

• 한국화재소방학회논문지
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• 제33권6호
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• pp.28-34
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• 2019

본 연구는 공간의 형태와 출입문의 개폐방향, 유도등 픽토그램의 형상에 따라 재실자(피실험자)들의 경로선택에 어떤 영향을 미치는지를 살펴보기 위한 것으로 컴퓨터 가상현실을 활용한 시뮬레이션 실험을 통해 수행하였다. T형 복도와 +형 복도를 대상으로 하여 시나리오별로 피난구유도등, 복도통로유도등을 배치하고 이를 컴퓨터 그래픽화하여 시뮬레이션을 수행하였다. 피난구유도등 픽토그램의 2가지 방향(좌, 우)에 대한 인간 행동의 반응(응답)과 출입구의 열리는 방향에 따른 영향 등을 분석하였다. 또한 통로유도등의 존재 유무에 따른 의사결정의 변화 등을 확인하였다. 실험결과, 방향선택 응답률을 살펴보면 첫째, T자형 복도에서 출입문에 유도등이 없을 경우, 출입문이 열리는 방향에 의해 영향을 받음을 알 수 있었다. 둘째, 출입문 상단에 유도등이 있을 경우에는 유도등 픽토그램의 방향과 일치하는 방향의 응답률이 높게 나타나 유도등의 픽토그램의 방향이 재실자의 피난경로선택에 영향을 미침을 확인하였다.

• 한국방사선학회논문지
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• 제2권1호
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• pp.23-29
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• 2008

본 연구에서는 웨이블릿 변환과 경계선 검출 필터를 이용하여 초음파영상의 다해상도 분해를 한 후 경계선 검출 필터링을 통해 초음파 영상의 화질을 개선하는 방안을 제안하였다. 제안된 방법에서는 잡음을 줄이고 에지를 강화하기 위해 웨이블릿 변환된 영상으로부터 얻어진 저해상도 영상에서 고해상도 영상으로 단계적으로 영역별 선택계수 조정과 방향성을 고려한 에지 필터링을 수행하였다. 이를 통해 반점영역의 픽셀은 웨이블릿 계수를 줄여 에지를 제외한 영역에서 선택적 저역통과 필터링 효과를 만들고, 에지에서는 접선 방향으로 평활화를 하여 연속성을 향상시키고, 법선 방향으로는 세선화를 하여 contrast를 높였다. 실험을 통해 단일해상도에서 비선형적 이방성의 확산모델을 이용한 필터링 방법과 웨이블릿 수축구조를 이용한 필터링 방법에 대해 비교하였다.

• Bulletin of the Korean Chemical Society
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• 제11권6호
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• pp.521-527
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• 1990

The binding characteristics and analytical applications of anilinium ion complexes with 18-crown-6 were studied by polarography and NMR. First, the electrochemical reduction of the 10 species of mono and dimethylsubstituted anilinium ion complexes with 18-crown-6 as host in methanol are examined. The addition of 18-crown-6 to anilinium guest solution the polarographic waves remain well defined but shifted toward more negative potentials, indicating the complex formation. The values of formation constants, log Κ for 10 species of methylsubstituted anilinium ion complexes with 18-crown-6 varies from 2.7 to 4.8 in methanol at $25^{\circ}C$. The stability order of complexes for 18-crown-6 is anilinilum > 4-methyl > 3,4-dimethyl > 3-methyl > 3,5-dimethyl > 2,4-dimethyl > 2,5-dimethyl > 2,3-dimethyl > 2-methyl > 2,6-dimethylanilinium ion. The steric hindrance shows significant effect. Second, Proton NMR was used to elucidate their interaction characteristics. From the results of so called NMR titration techniques, the behaviors of binding sites on complexation, and the stoichiometry and stability order of complex were obtained. And the later results show the satisfactory agreement with the quantitative values obtained by polarography. Finally, the individual determinations of anilinium ion mixtures were also accomplished by addition of 18-crown-6. In some mixtures of methyl or dimethylanilinium ions the reduction peaks of differential pulse method appeared into one unresolved wave attributed to the small difference of half-wave potential, ${\Delta}E_{1/2}$. In the presence of 18-crown-6, the polarographic waves were resolved into individual maxima because of the shift toward more negative direction by the difference of selectivity of anilinium ions with 18-crown-6. It may be concluded that quantitative analysis of methylanilinium ion mixture make possible because the half-wave potential shift by the selectivity difference due to the steric hindrance between methyl group and 18-crown-6 on complexation.

• Bulletin of the Korean Chemical Society
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• 제33권3호
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• pp.1047-1051
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• 2012

The nucleophilic substitution reactions of (2R,4R,5S)-(+)-2-chloro-3,4-dimethyl-5-phenyl-1,3,2-oxazaphospholidine 2-sulfide with X-pyridines are investigated kinetically in acetonitrile at $5.0^{\circ}C$. The free energy relationships for substituent X variations in the nucleophiles exhibit biphasic concave upwards with a break point at X = 3-Ac. Unusual positive $\rho_X$ (= +4.73) and negative ${\beta}_X$ (= -0.75) values are obtained with the weakly basic pyridines, and rationalized by the isokinetic relationship with isokinetic temperature at $t_{ISOKINETIC}=39.3^{\circ}C$. A concerted mechanism involving a change of nucleophilic attacking direction from a frontside attack with the strongly basic pyridines to a backside attack with the weakly basic pyridines is proposed on the basis of greater magnitudes of selectivity parameters ($\rho_X$ = -6.15 and ${\beta}_X$ = 1.11) with the strongly basic pyridines compared to those ($\rho_X$ = 4.73 and ${\beta}_X$ = -0.75) with the weakly basic pyridines.

• 한국응용과학기술학회지
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• 제30권1호
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• pp.96-115
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• 2013

본 연구는 항균성 코팅제의 개념과 동향파악으로 항균성 코팅제의 연구개발의 방향을 설정하는데 도움을 주기 위한 것이다. 항균제는 미생물을 제거하거나 성장을 저지하는데 사용되는 화합물이며 항균 코팅제에 함유되는 항균제용 재료는 무기물, 금속, 저분자 유기물, 천연유기물, 고분자가 있다. 항균코팅제는 생활용품, 병원용품, 산업용품, 전자제품, 의류, 건축 내장재 등의 표면의 항균성 부여에 쓰인다. 기존 항생제는 세균의 세포벽을 손상하지 않고 미생물을 침투하나 항균성 고분자는 세포막을 파괴하므로 항생제의 내성을 방지할 수 있다. 대부분의 고분자 항균제는 양이온 고분자에 초점을 맞추고 있다. 항균제의 분자설계와 코팅제 배합의 합리화로 항균제의 선택성, 내구성, 독성 문제가 개선될 것이다.