• 한국광학회지
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• 제8권2호
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• pp.81-87
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• 1997

본 논문은 4군구성의 비디오 카메라용 줌광학계에 대해 렌즈모듈의 개념을 이용하여 1차량 및 3차 수차를 고려한 최적의 초기설계와 이로부터 설계 줌광학계를 설계하는 방법을 제안하였다. 최적화 과정을 통해 각각의 렌즈모듈에 적절히 1차량과 3차 수차량을 설정함으로써 줌비 10배(f'=6.1693~58.4065)를 갖고, 최적설계에 필요한 구속조건을 만족시키는 초기설계 줌광학계를 얻었다. 적절히 선정된 각각의 렌즈군의 촛점거리가 렌즈모듈의 촛점거리와 같도록 scaling 한 후, 군사이의 공기간격을 조정하므로써 줌궤적을 일치시켰다. 이러한 과정을 통해 독립적으로 설계된 군들을 결합시켜 얻은 줌광학계는 렌즈모듈로 구성된 원래의 초기설계된 줌광학계와 동일한 1차특성을 갖는다. 결과적으로 잔여수차 보정을 통해 후군촛점조절방식을 이용하는 비디오 카메라 줌렌즈로서 유용한 줌광학계를 얻을 수 있었다.

• Journal of the Optical Society of Korea
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• 제20권4호
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• pp.515-523
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• 2016

Spectral reflectance is sparse in space, and while the traditional spectral-reconstruction algorithm does not make full use of this characteristic sparseness, the compressive sensing algorithm can make full use of it. In this paper, on the basis of analyzing compressive sensing based on the orthogonal matching pursuit algorithm, a new algorithm based on the Dice matching criterion is proposed. The Dice similarity coefficient is introduced, to calculate the correlation coefficient of the atoms and the residual error, and is used to select the atoms from a library. The accuracy of Spectral reconstruction based on the pseudo-inverse method, Wiener estimation method, OMP algorithm, and DOMP algorithm is compared by simulation on the MATLAB platform and experimental testing. The result is that spectral-reconstruction accuracy based on the DOMP algorithm is higher than for the other three methods. The root-mean-square error and color difference decreases with an increasing number of principal components. The reconstruction error decreases as the number of iterations increases. Spectral reconstruction based on the DOMP algorithm can improve the accuracy of color-information replication effectively, and high-accuracy color-information reproduction can be realized.

• Journal of Electrochemical Science and Technology
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• 제9권3호
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• pp.220-228
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• 2018

This study introduced a carbon-free electrode for $Li-O_2$ cells with the aim of suppressing the side reactions activated by carbon material. Micro-particles of poly(3,4-ethylenedioxythiophene) (PEDOT), a conducting polymer, were used as the base material for the air electrode of $Li-O_2$cells. The PEDOT micro-particles were treated with $H_2SO_4$ to improve their electronic conductivity, and LiBr and CsBr were used as the redox mediators to facilitate the dissociation of there action products in the electrode and reduce the over-potential of the $Li-O_2$ cells. The capacity of the electrode employing PEDOT micro-particles was significantly enhanced via $H_2SO_4$ treatment, which is attributed to the increased electronic conductivity. The considerable capacity enhancement and relatively low over-potential of the electrode employing $H_2SO_4$-treated PEDOT micro-particles indicate that the treated PEDOT micro-particles can act as reaction sites and provide storage space for the reaction products. The cyclic performance of the electrode employing $H_2SO_4$-treated PEDOT micro-particles was superior to that of a carbon electrode. The results of the Fourier-transform infrared spectroscopic analysis showed that the accumulation of residual reaction products during cycling was significantly reduced by introducing the carbon-free electrode based on $H_2SO_4$-treated PEDOT micro-particles, compared with that of the carbon electrode. The cycle life was improved owing to the effect of the redox mediators. The refore, the use of the carbon -free electrode combined with redox mediators could realize excellent cyclic performance and low over-potential simultaneously.

• 한국산학기술학회논문지
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• 제14권4호
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• pp.1883-1889
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• 2013

Fe-Si계 합금은 우주탐사용으로 응용되고 있는 Si-Ge합금보다는 낮은 성능지수를 나타내지만 원료가 풍부하여 저가이고, 제조가 간단하며, $800^{\circ}C$까지 사용가능한 중고온용 열전발전재료이다. 본 연구에서는 고주파 진공유도로를 이용해서 제조한 p형 $FeSi_2$의 열전물성에 미치는 입자크기 및 첨가물 영향에 대해 조사하였다. 조성입자크기가 작을수록 소결밀도 증가와 함께 입자와 입자간의 연결성 향상에 의해 도전율이 증가하였다. Seebeck 계수는 600~800K에서 최고값을 나타내었고, 잔존하는 ${\varepsilon}$-FeSi 금속전도상에 의해 약간 감소하였다. $Fe_2O_3$ 및 $Fe_3O_4$를 첨가한 경우, 잔존 금속전도상 및 Si 결핍양 증가에 의해 도전율은 증가하였고 Seebeck 계수는 감소하였다. 반면에 $SiO_2$를 첨가한 경우에는 도전율과 Seebeck 계수 모두 상승하였다.

• 터널과지하공간
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• 제18권3호
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• pp.226-238
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• 2008

숏크리트의 지보성능을 보완하기 위해 사용되는 강지보재는 매우 효과적인 것으로 평가되지만 강지보재 종류별 성능이 파악되지 못하여 설계에 제대로 반영하지는 못하고 있다. 본 연구에서는 여러 가지 강지보재에 의해 보강된 숏크리트의 특성을 휨인성 시험을 통하여 파악하고, 그 결과를 수치해석에 반영하고자 하였다. 시험결과 철근보강 숏크리트는 H 형강이나 격자지보에 비해 지보능력이 다소 못 미치는 것으로 나타났는데, 이는 시험체가 휨인장 파괴를 유도하기에는 다소 짧아서 전단파괴가 발생하였기 때문인 것으로 나타났다. 수치해석을 이용한 안정성 해석 시 숏크리트와 강지보재를 별도로, 그리고 이들 복합체에 대한 등가물성을 구하여 각각 해석한 바 두 결과가 잘 일치하여 등가물성을 이용한 복합체 해석으로도 간편하게 강지보재의 효과를 모사할 수 있었다.

• 한국토양비료학회지
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• 제46권4호
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• pp.260-269
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• 2013

Two single-crystals of fully dehydrated, partially $Li^+$-exchanged zeolites X (Si/Al = 1.09, crystal 1) and Y (Si/Al = 1.56, crystal 2), were prepared by flow method using 0.1 M $LiNO_3$ at 393 K for 48 h, respectively, followed by vacuum dehydration at 673 K and $1{\times}10^{-6}$ Torr. Their structures were determined by single-crystal X-ray diffraction techniques in the cubic space group $Fd\bar{3}$ and $Fd\bar{3}m$ at 100(1) K for crystals 1 and 2, respectively. They were refined to the final error indices $R_1/wR_2$ = 0.065/0.211 and 0.043/0.169 for crystals 1 and 2, respectively. In crystal 1, about 53 $Li^+$ ions per unit cell are found at three distinct positions; 9 at site I', 19 at another site I', and the remaining 25 at site II. The residual 25 $Na^+$ ions occupy three equipoints; 2 are at site I, 7 at site II, and 16 at site III'. In crystal 2, about 31 $Li^+$ ions per unit cell occupy sites I' and II with occupancies at 22 and 9, respectively; 3, 4, 23, and 3 $Na^+$ ions are found at sites I, I', II, and III', respectively. The extent of $Li^+$ ion exchange into zeolite X (crystal 1) is higher than that of zeolite Y (crystal 2), ca. 73% and 56% in crystals 1 and 2, respectively.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권3호
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• pp.215-220
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• 1999

$SO_2$and CO gas removal characteristics of a wire-to-cylinder type nonthermal discharge plasma reactor in various applied voltage (-dc, ac, fast rising pulse and high frequency pulse) and a crossed dc magnetic field have been investigated. The experiment has been emphasized on the oxidizing characteristics of $SO_2$ and CO gas by $O_3$ and the applying of a crossed magnetic field, which would induce the cyclotronic and drift motions of electrons making the residual time longer in the removal airgap space. And it also would enhance the energy of electrons and the electrophysicochemical actions to remove the pollutant gases effectively. It is found thatthe corona onset voltage and the breakdown voltage were decreased with increasing the crossed magnetic field and decrease initial fed $SO_2$and CO concentration. As a result, a higher ozone generation and $SO_2$ and CO gas removal rate of 20[%] can be obtained with -dc, ac and fast rising pulse corona discharges in the crossed dc current-induced magnetic field. But high frequency pulse didn't show effect in applying of a crossed magnetic field.

• Tuberculosis and Respiratory Diseases
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• 제45권4호
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• pp.888-895
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• 1998

Malaria is one of the most common infectious diseases in the world. Plasmodium falciparum, accounting for nearly all malaria mortality, kills an estimated 1 to 2 million persons yearly and has several features that make it deadlist of malarias. While cerebral malaria is the most common presentation of severe disease, acute lung injury associated with malaria is uncommon but serious and fatal complication. We report two cases of severe malaria with ARDS and multi-organ failure. All two patients traveled to foreign countries, Kenya, Papua New Guinea where choroquine-resistant malaria is distributed. The first case, which developed cerebral malaria, hypoglycemia, multi-organ failure, and ARDS, treated with quinine and mechanical ventilator, but expired due to oxygenation failure. Autopsy showed acute necrotizing infiltration, diffuse eosinophilic fibrinoid deposits along the alveolar space, and alveolar macrophage with malaria pigment The second case also developed multi-organ failure, followed by ARDS, and was treated with quinine, exchange transfusion, plasmapheresis, and mechanical ventilator. He recovered with residual restrictive lung change after treatment.

• 한국광학회지
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• 제16권1호
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• pp.34-42
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• 2005

본 논문은 3군 구성의 줌 광학계에 대해 렌즈모듈의 개념을 이용하여 1차량 및 3차 수차를 고려한 최적의 초기설계와 이로부터 실제 줌 광학계를 설계하는 방법을 제안 하였다. 각각의 렌즈모듈에 적절히 1차량과 3차 수차량을 설정함으로써 줌비 2배(f = 4.3∼8.6 mm)를 갖고, 시스템에서 요구하는 구속조건을 만족시키는 초기설계 줌 광학계를 얻었다. 각 군의 역할에 따라 적절히 선정된 각각의 렌즈군의 초점거리 및 1차량이 렌즈모듈의 값과 같도록 독립적으로 설계한 후, 군사이의 공기간격을 조정하므로써 줌궤적을 일치시켰다. 이러한 과정을 통해 설계된 줌 광학계는 렌즈모듈로 구성된 원래의 초기 설계된 줌 광학계와 동일한 1차 특성을 갖는다. 결과적으로 잔여수차 보정을 통해 후군초점조절방식을 이용하는 컴팩트 디지털 카메라 및 모바일 폰용 줌 렌즈로서 유용한 줌 광학계를 얻을 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제8권2호
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• pp.69-72
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• 1987

The structures of dehydrated $Ag_9Cs_3$-A treated with hydrogen gas at three different temperatures have been determined by single-crystal X-ray diffraction techniques. Their structures were solved and refined in the cubic space group Pm3m at 23(1) $^{\circ}C$. All crystals were ion exchanged in flowing streams of aqueous $AgNO_3$/$CsNO_3$ with a mole ratio 1:3.0 to achieve the desired crystal composition. The structures treated with hydrogen at $23^{\circ}C(a=12.288(1)\;{\AA})\;and\;310^{\circ}C(a=12.291(2)\;{\AA})$ refined to the final error indices R1 = 0.091 and R2 = 0.079, and 0.065 and 0.073, respectively, using the 216 and 227 reflections, respectively, for which I >3${\sigma}$(I). In both of these structures, eight $Ag^+$ ions are found nearly at 6-ring centers, and three $Cs^+$ ions lie at the centers of the 8-rings at sites of $D_{4h}$ symmetry. One $Ag^{\circ}atom$, presumably formed from the reduction of a $Ag^+$ ion by an oxide ion of a residual water molecule or of the zeolite framework during the dehydration process, is retained within the zeolite, perhaps in a cluster. In these two structures hydrogen gas could not enter the zeolite to reduce the $Ag^+$ ions because the large $Cs^+$ ions blocked all the 8-windows. However, hydrogen could slowly diffuse into the zeolite and was able to reach and to reduce about half of the $Ag^+$ ions in the structure only at high temperature ($470^{\circ}C$). The silver atoms produced migrated out of the zeolite framework, and the protons generated led to substantial crystal damage.