새로운 Acetylcholinesterase inhibitors의 합성

최순규,김형민,조승환,최학기,박유미,이용균,정대일,김인식,한정태 동아대학교 부설 기초과학연구소 2004 基礎科學硏究論文集 Vol.21 No.1

노인성 치매의 일종인 alzheimer's disease의 효과적인 억제제를 합성하기 위해 우리는 분자 모델링에 의한 가장 적합한 물질인 m-[(N,N,N-trimethylammonio)phenyl]boronic acid를 합성하였다. 출발물질인 3-aminophenylboronic acid monohydrate의 경우 boronic acid의 작용기인 hydroxyl group을 protecting시킴으로써 반응의 안정성을 기하였다. Quarternary ammonium salt는 과량의 methyliodide와 염기 촉매인 potassium hydrogen carbonate를 사용하여 용매인 methanol에서 반응시켜 상당히 높은 수율을 얻을 수 있었다. 또한 과량의 methyliodide와 염기촉매인 potassium hydrogen carbonate를 사용하여 용매인 methanol에서 반응시킨 결과 boronic acid의 protection없이도 안정하게 반응이 진행되어짐을 확인할 수 있었다. In order to syntheisize a effective inhibotor for alzheimer's disease, we synthesized m-[(N,N,N-trimethylammonio)phenyl]boronic acid 4 which is designed by molecular modeling form. We protected the hydroxyl group of 3-aminophenylboronic acid monohydrate 1 with ethlyne glycol to remove the reactivity if hydroxyl group. To synthesize m-[(N,N,N-trimethylammonio)phenyl]boronic acid 4, we reacted 3-aminophenylboronic acid monohydrate 1 with ezcess methyl iodide and potassium hydrogen carbonate as a base-catalyst in methanol. but On executed reaction without protection on hydroxyl group, we found out the result that the hydroxyl group of boronic acid group at 3-aminophenylboronic acid monohydrate 1 didn't react with excess methyliodide. Synthesized m-[(N,N,N-trimethylammonio)phenyl]boronic acid 4 is in progress about biological tests as a plausible acetylcholinesterase inhibitor.

철근 또는 강판을 이용한 철근콘크리트 전단벽의 휨성능개선에 관한 실험연구

하기주,서수연,신종학,최민권 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.1(구조계)

The purpose of this paper is to study retrofit methods for improving the flexural capacity of RC shear wall. Four RC shear wall specimens are designed and strengthened by using reinforcement or steel plate. Cyclic loads are applied to the specimen under constant axial force. Test result shows that the strength and ductility of specimen is improved when it is strengthened using reinforcement or steel plate. The specimen retrofitted by using steel plate shows high ductility. However the strength contribution of one is not much. It is shown that the most effective method is both to install the additional flexural reinforcement and to confine the ends of wall.

후면 패치를 갖는 광대역 사다리꼴 모노폴 안테나의 설계

최환기(Hwan-Gi Choi),최학근(Hak-Keun Choi),이형기(Hyoung-Ki Lee) 한국전자파학회 2009 한국전자파학회논문지 Vol.20 No.7

본 논문에서는 PCS/WCDMA/WiBro/S-DMB(1.750~2.655 ㎓) 공용 모노폴 안테나로서 사용 가능한 광대역 모노폴 안테나를 제안한다. 제안된 안테나는 FR-4 기판에 제작된 사다리꼴 모노폴 안테나의 후면에 패치를 추가하여 대역폭을 개선시킨다. 제안된 안테나의 광대역 특성과 복사 패턴을 확인하기 위하여 설계된 안테나를 제작하고 복사 특성을 측정하여 계산된 결과와 비교하였다. 측정 결과는 계산 결과와 비슷하게 나타났으며, 사용 대역 내에서 2 ㏈i 이상의 이득을 가지며, 1.73~3.48 ㎓ 대역(중심 주파수 기준 67.2 %)에서 1.5:1 이하의 VSWR을 갖는 것으로 나타났다. 본 논문에서 설계된 모노폴 안테나는 PCS/WCDMA/WiBro/S-DMB 공용 실내용 안테나로 사용할 수 있을 것으로 생각된다. In this paper, a wide-band monopole antenna for use in PCS/WCDMA/WiBro/S-DMB(1.750~2.655 ㎓) band is presented. The presented antenna is a trapezoidal monopole antenna which has back-side patch and improves the bandwidth. To confirm the wide-band characteristics and radiation pattern of presented antenna, the experimental antenna is fabricated and its radiation characteristics are measured, compared with calculated results. It is shown that the designed antenna has VSWR less than 1.5, gain over 2 ㏈i in 1.73~3.48 ㎓. The measured results show good agreement with calculated results. From the result, we confirm that the designed antenna can be used indoor antenna for PCS/WCDMA/WiBro/S-DMB.

이득 평탄도 개선을 위한 광대역 반사판 부 다이폴 안테나 설계

최환기(Hwan-Gi Choi),최학근(Hak-Keun Choi),김도경(Do-Kyung Kim) 한국전자파학회 2008 한국전자파학회논문지 Vol.19 No.7

본 논문에서는 PCS/WCDMA/WiBro(1.750~2.39 ㎓) 공용 기지국 배열 안테나로서 사용 가능한 광대역 다이폴 안테나를 제안한다. 제안된 안테나는 반사 소자를 갖는 반사판 부 다이폴 안테나로서 이득 평탄도를 개선시킨다. 제안된 안테나의 광대역 특성과 개선된 이득 평탄도를 확인하기 위하여 실제 안테나를 제작하고, 복사 특성을 측정하여 계산된 결과와 비교하였다. 측정 결과는 계산 결과와 비슷하게 나타났으며, 1.75~2.39 ㎓ 대역에서 0.74 ㏈의 이득 평탄도와 5 ㏈i 이상의 이득, 1.5:1 이하의 VSWR을 갖는 것으로 나타났다. 본 논문에서 설계된 다이폴 안테나는 PCS/WCDMA/WiBro 공용 배열 안테나의 배열 소자로 사용할 수 있을 것으로 생각된다. In this paper, a wide-band dipole antenna suitable for use in PCS/WCDMA/WiBro(1.750~2.39 ㎓) base station array antenna is presented. The presented antenna is a dipole antenna with pate which has the reflector element and improves the gain flatness. To confirm the wide-band characteristics and the gain flatness of the presented antenna, the experimental antenna is fabricated and its radiation characteristics are measured, compared with calculated results. It is shown that the designed antenna has VSWR less than 1.5, gain over 5 ㏈i, and gain flatness 0.74 ㏈ in 1.75~2.39 ㎓. The measured results show good agreement with the calculated results. From these results, we confirm that the designed antenna can be used as a array element of the wide-band base station array antenna for PCS/WCDMA/WiBro.

평판이 삽입된 IBBD 배열 안테나의 복사 특성 분석

최환기(Hwan-Gi Choi),최학근(Hak-Keun Choi),김도경(Do-Kyung Kim),정영배(Young-Bae Jung),전순익(Soon-Ik Jeon) 한국전자파학회 2008 한국전자파학회논문지 Vol.19 No.11

본 논문에서는 지능형 안테나 시스템을 위하여 IBBD 배열 안테나의 소자 간격 및 소자 사이에 삽입된 평판의 높이에 따른 격리도를 분석하였다. 배열 소자 사이의 격리도는 두 소자 사이의 배열 간격이 증가할수록 향상되고, 두 소자 사이에 평판을 삽입한 경우가 평판이 없는 경우보다 약 13 ㏈의 격리도가 향상되는 것을 확인하였다. 또, 평판이 삽입된 4×4 소자 IBBD 배열 안테나를 제작하여 평판의 높이에 따른 복사 특성을 측정하고 분석하였다. 평판의 높이가 증가함에 따라 이득이 약간 감소하나, 복사 패턴 형상에는 거의 변화가 없었다. In this paper, the isolation of the IBBD array antenna is analyzed as functions of the element spacing and the height of the flat plate inserted between array elements for the intelligent antenna system. It is found that the isolation between array elements improves with increasing the array spacing. The array configuration with the plate between the elements is enhanced by about 13 ㏈ more in the isolation than the one without the plate. The plate-inserted 4×4 elements IBBD array antennas are fabricated and the radiation characteristics are measured and analyzed for the various heights of the plate. It is found that the gain decreases slightly with increasing the height of plate but the shape of radiation pattern does not show a remarkable change.

WiBro/WiMAX 대역 IBBD 배열 안테나의 설계

최환기(Hwan-Gi Choi),최학근(Hak-Keun Choi),정영배(Young-Bae Jung),전순익(Soon-Ik Jeon) 한국전자파학회 2008 한국전자파학회논문지 Vol.19 No.1

본 논문에서는 WiBro/WiMAX 대역(2.3~3.5 ㎓)에서 동작하는 광대역 16(4×4) 소자 배열 구형 반사판 안테나를 설계하고, 복사 특성을 고찰하였다. 설계된 안테나는 IBBD(Integrated Balun Bow-tie Dipole) 소자로 구성되며, 급전 회로에서 발생하는 불요 전자파를 줄이기 위하여 반사판 뒷면에 급전 회로를 두었다. 설계된 안테나의 광대역 특성을 확인하기 위하여 실제 안테나를 제작하고 복사 특성을 측정하여 계산된 결과와 비교하였다. 측정결과는 계산 결과와 비슷하게 나타났으며, 2.06~3.89 ㎓ 대역에서 VSWR 1.6 이하를 만족하였고, 안테나 이득은 사용 주파수 대역에서 10.3 ㏈i 이상으로 나타났다. 따라서 본 논문에서 설계된 안테나는 WiBro/WiMAX 공용 배열 안테나로 사용할 수 있을 것으로 생각된다. In this paper, a broadband rectangular reflector antenna with 16-array elements for WiBro/WiMAX band(2.3~3.5 ㎓) is designed, and its radiation characteristics are investigated. The designed antenna is composed of theIBBD(Integrated Balun Bow-tie Dipole) elements and has the feed circuit at the rear of the reflector to reduce the unwanted electromagnetic wave from it. To confirm the broadband characteristics of the designed antenna, test antenna is fabricated and its radiation characteristics are measured, compared with calculated results. The measured results show good agreement with the calculated results. As a result of measurements, 1.8 ㎓ of bandwidth(VSWR<1.6) is achieved at 2.06~3.89 ㎓ and the antenna gain over 10.3 ㏈i. We confirm that the designed antenna can be used as a broadband antenna for WiBro/WiMAX.

Vapor Coating Method Using Small-Molecule Organic Surface Modifiers to Replace N-Type Metal Oxide Layers in Inverted Polymer Solar Cells

Choi, Hyosung,Kim, Hak-Beom,Ko, Seo-Jin,Kim, Gi-Hwan,Kim, Jin Young American Chemical Society 2014 ACS APPLIED MATERIALS & INTERFACES Vol.6 No.9

<P>We investigate a simple fabrication method for vapor coating small-molecule organic interlayers as replacements for metal oxide films. The interfacial layers, which serve both as both surface modifiers to reduce the substrate work function and electron selective layers, maximize light absorption within the active layer while improving electron transport and compatibility between the active layer and cathode, leading to a ∼22% enhancement in power conversion efficiency and similar air stability compared to devices using a ZnO layer.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2014/aamick.2014.6.issue-9/am500092a/production/images/medium/am-2014-00092a_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am500092a'>ACS Electronic Supporting Info</A></P>

Design of wide‐band dual‐polarized antennas with plate for improving gain characteristics

Choi, Hwan‐,Gi,Choi, Hak‐,Keun John Wiley Sons, Inc. 2019 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS Vol.61 No.3

<P><B>Abstract</B></P><P>In this article, a wideband dual‐polarized antenna that can be used in the 1.7‐3.7 GHz band is proposed. The proposed antenna is a dual‐polarized antenna with a plate having a parasitic elements and it improves the gain characteristics in wide‐band. In general, an antenna with a reflection plate is difficult to have a constant gain characteristic in the wide‐band, because the electrical distance between the radiation elements and the reflection plate is variable for the bandwidth. In this article, a parasitic element is assigned to the front side of the radiation element to improve the gain of the band in which the characteristic is degraded. The proposed antenna has the VSWR < 2:1 in the band of 1540‐3795 MHz (84.5% of center frequency) and has a gain of 7.92 dBi or more at the measured frequency.</P>

A Durability Study of a Paracorporeal Pulsatile Electro‐Mechanical Pneumatic Biventricular Assist Device

Choi, Hyuk,Lee, Heung‐,Man,Nam, Kyoung Won,Choi, Jaesoon,Lee, Jung‐,Joo,Kim, Ho Chul,Song, Seung Joon,Ahn, Chi Bum,Son, Ho Sung,Lim, Choon Hak,Son, Kuk Hui,Park, Yong Doo,Jeong, Gi Seok,Su Blackwell Publishing Inc 2011 Artificial Organs Vol.35 No.6

<P><B>Abstract</B></P><P>In 2002, the paracorporeal pulsatile electro‐mechanical pneumatic ventricular assist device (VAD) began to be developed by the Korea Artificial Organ Center at Korea University under a Health & Medical Technology Research and Development program which finished in 2008. In vitro durability testing was conducted on the paracorporeal pulsatile pneumatic VAD to determine device durability and to evaluate device failures. The 1‐ and 2‐year reliability of the paracorporeal pulsatile pneumatic VAD was shown to be 91.2% and 54.9%, respectively, with an 80% confidence level. Failure modes were analyzed using fault tree analysis, with customized software continuously acquiring data during the test period. After this period, 21 in vivo animal tests were done, with 14 cases of left atrium to left ventricle (LV) inflow cannulation (36Fr)/outflow grafting to descending aorta, and seven cases of apex cannulation of LV to descending aorta (12 mm). The longest postoperative day (182 days) in Korea was recently recorded in in vivo animal testing (bovine, 90 kg, male, 3.5–4.0 L/min flow rate, and 55 bpm).</P>

Expression of Speclfic Proteins in Hanwoo Cervical Mucus during Spontaneous and Induced Estrus Synchronization

Hak-Jae Chung,Nam-Kuk Kim,Hwi-Cheul Lee,Won-Kyong Chang,Su-Bong Park,Suk-Dong Lee,Dong-Min Yoo,Jin-Sung Ko,Yon-Ho Choy,Seong-Bok Choi,Gi-Jun Jeon,Myeoung-Sik Lee,Seok-Ki Im 한국동물번식학회 2009 Reproductive & Developmental Biology(Supplement) Vol.33 No.2s