무인잠수정의 3-D 위치 계측시스템 개발

김희철,임종환,강철웅 제주대학교 공과대학 첨단기술연구소 2003 尖端技術硏究所論文集 Vol.14 No.2

This paper presents a 3-D localization method of an autonomous underwater vehicle(AUV). Conventional methods of localization, such as LBL or SBL, require additional beacon systems, which reduces the flexibility and availability of the AUV. We use a digital compass, a pressure sensor, a clinometer and ultrasonic sensors for localization From the orientation and velocity information, a priori position of the AUV is estimated based on the dead reckoning method Based on the extended Kalman filter algorithm, a posteriori position of the AUV is, then, estimated by using the distance between the AUV and a mother ship on the surface of the water together with the depth information from the pressure sensor. Simulation results show the possibility of practical application of the method to the autonomous navigation of the AUV.

상분리법을 통하여 제조된 새로운 개념의 지지형 액막의 기체투과특성

최평호,김범식,이정민,김철웅,구기갑,이상학 한국공업화학회 2004 공업화학 Vol.15 No.1

새로운 지지형 액막(SLM)을 용매 증발에 따른 1차, 2차 상분리법으로 3성분 고분자 용액으로부터 제조하였다. 액막재로 이온액인 BMIBF_(4) (BMI+ =1-(1-butyl)-3-methylimidazolium, BF_(4)=tetra-fluoro boratr)와 매트릭스 고분자로 polyvinylidenefluoride(PVDF)가 사용되었다. 이 고정화 액막의 O_(2), N_(2) 그리고 CO_(2) 기체 투과특성을 여러 조작 조건에서 조사하였다. SLM은 가혹한 조건에서 조작하였음에도 불구하고 오랜 시간동안 높은 CO_(2) 투과도 및 선택성을 유지하였다. 투과거동을 나타내는 인자인 투과도, 확산도, 그리고 용해도를 연속 측정 장치를 통하여 구함으로써 특성을 관찰하였다. SLM은 다른 기체에 비하여 CO_(2)에 대해서 높은 투과도와 선택도를 갖고 있었다. 특히, 막내 CO_(2)의 용해도는 다른 기체들에 비하여 매우 높은 반면 확산도는 큰 차이를 보이지 않았다. 또한 막내 이온액의 조성은 CO_(2) 용해도에 영향을 관찰할 수 있었다. 막내 이온액의 조성이 증가함에 따라서 CO_(2) 의 투과도 및 선택도가 극격히 증가하였다. 이는 SLM를 통한 기체 투과에 있어서 용해도가 주인자로 큰 영향을 끼침으로써 막내 이온액 조성 증가 SLM의 투과에 큰 영향을 미침을 확인하였다. The new supported liquid membranes (SLMs) were fabricated from ternary polymer solution contained ionic liquid in which primary and secondary phase separations were induced by the solvent by the solvent evaporaton. The used ionic liquid and polymer matrix were BMBF_(4) (BMI+=-(1-butyl)-3-methylimidazolium, BF_(4)-tetra-fluoro boratel and polyvinylidene fluoride (PVDF). Gas permeation properties of the SLM to O_(2), N_(2) and CO_(2) were studied at various operating conditions. Although the SLM were operated under severe operating condition, it maintained high CO_(2) permeability and selectivity for quite long time. The solubility coefficient of CO_(2) in the membrace was very high in comparison with those of other gases; whereas there was no big difference in the diffusivity between CO and other gases. Moreover, in the permeation of pure gases, it is observed that the ionic liquid content in the membrane affected the solubility of CO_(2) in the memhranc. With increasing ionic liquid content in the membrane, the permeability and selectivity of CO_(2) increase significantly. There fore, in the permeation of gases through SLM, the overall permeation performances weir affected mainly by solubility coefficient. This observation can be discussed in terms of the influence of solubility coefficient with ionic liquid content in the membrane.

펜틸렌테트라졸 투여 흰쥐에서의 천마의 항경련 작용기전

허근,김진숙,권태협,김정애,용철순,하정희,이동웅 영남대학교 약품개발연구소 1998 영남대학교 약품개발연구소 연구업적집 Vol.8 No.-

Gastrodia elata (GE) is a oriental medicinal herb which has been used traditionally for the treatment of various brain diseases including convulsion and epilepsy. In order to examine the mechanism of anticonvulsive effect, we treated the methanol extract of GE (500 mg/kg, P.O) to the pentylenetetrazole (PTZ)-induced convulsive rats. Methanol extracts of GE siginificantly inhibited (35%) the convulsion state as well as the level of lipid peroxidation (25%) in the brain. The ether fraction of methanol extracts among the others effectively inhibited in vitro lipid peroxidation dose dependently (5.0×10^(-6)~2.0×10^(-5) g/ml). The scavenging effect on hydroxy radicals was found in all the fractions of ether, butanol, and dichloromethane. These results suggest that the anticonvulsive effect of GE is possibly due to the antioxidative effects of the active components in GE.

충적 소하천 유역의 부유사량 산정

홍진표,김웅용,이대철 大田産業大學校 1997 한밭대학교 논문집 Vol.14 No.1

A method is presented which enables the computation of the suspended sediment load transport rate as the product of particle velocity and sediment load concentration. In this study, it is assumed that particle velocity is expressed by mean flow velocity near the particle. The data is obtained at San-Gye station at Bochong stream in Geum river and is analyzed by the Einstein H. A., Lane-Kalinske, Chang-Simon-Richardson, and Itakura and Kishi formulas. The results show that estimated values by Itakura-Kishi formula for the calculation of suspended sediment load quantity in small alluvial stream. Itakura-Kishi formula will be able to use on the development of loafer resources at small stream in the future.

노말브틸아크릴레이트/메틸메타아크릴레이트계 유화중합에 관한 계면활성제의 영향

고기영,김철웅,김광주,구기갑 한국공업화학회 2002 응용화학 Vol.6 No.2

Polymer latexes for polymer cement were prepared by introducing small amount offunctional monomers(acrylic acid and acrylic amide) during the semicontinuousemulsion polymerization of methylmetacrylate(MMA) and n-butyl acrylate(n-BA). Thepolymerization was investigated by following the variation of the amount and type, of surfactants on particle size, polymer content at different times of the polymerization process. The results showed that both particle size and polymer content can be controlled by the amout and types of surfactants. LE and NE types out of nonionic surfactants used were good surfactants due to the formation of stable polymer latex without coagulants. Especially, a hydrophilic chain length(n) of these nonionic surgactants had a signigicant effect on the final particle size and polymer content.

Nonlinear Cardiac Dynamics and Morning Dip : 위험한 일중리듬 An Unsound Circadian Rhythm

염명걸,김남수,오재원,김창렬,이재웅,김순길,이철범,노정일,최정연,윤용수 대한순환기학회 1998 Korean Circulation Journal Vol.28 No.3

다양한 함불소가스들의 고비점 용매에 관한 용해도 측정 및 엑막에 의한 분리

최평호,이상학,김철웅,김범식,김광주,이정민,박인준 한국공업화학회 2002 응용화학 Vol.6 No.2

The solubility of various fluoro-gases in high boiling-point solvents, n-Cnh_2n+_1OH(6<n<10)and ionic liquids(+ ions: 1-Buty 1-3-methy1-imidazolium, 1-Ethy1-3-methy1-imidazolium, - ions:BF_4, PF_6, S_6F_6, F_6O_4S_6) were measured at temperatures from 0 to 30℃, at total pressures up to 4 bat Solubility increased significantly with the decrease of n in n-Cn_2N+OH and showed no such a difference in the types of ionic liquids, Especially, the solubility of R22 gas in these solvents increases rapidly with increases in pressure and decreases in temperature, whereas other fluoro-gases were showed a little solubility Liquid-supported membranes were prepared with these solvents and polymer matrix and were applied to the separation of fluoro-gases including R22 gas. A high permeability and selectivity were exhibited in R22 gas against other fluoro-gases.

천마의 GABA-benzodiazepine 수용체 복합체에 대한 조절작용

하정희,이동웅,어경윤,하정상,김현주,용철순,허근 영남대학교 약품개발연구소 1998 영남대학교 약품개발연구소 연구업적집 Vol.8 No.-

Methanol extract of G. elata inhibited the binding of [³H]Ro15-1788, a selective benzodiazepine receptor antagonist, to benzodiazepine receptor of rat cortices. Saturation experiments followed by Scatchard analysis of the results showed that the inhibition of [³H]Ro15-1788 binding by G. elata. appeared to be competitive. These competitive inhibiton of the butanol fraction was observed to be higher than the methanol extract. Methanol extract of G. elata inhibited a [³H]flunitrazepam, a selective benzodiazepine receptor agonist, binding to benzodiazepine receptor. GABA significantly enhanced the inhibition of [³H]flunitrazepam binding by G. elata, and these "positive GABA shift" supported the strong possibility of agonistic activity to benzodiazepine receptor. Butanol fraction was observed to be higher than crude extract by methanol in an agonistic activity to benzodiazepine receptor, furthermore enhanced the binding of [³H]SR95531 to GABA_(A) receptor. Butanol fraction of G. elata significantly diminished the pentylenetetrazole-induced lethality of mice. From these results, it can be concluded that substance or substances with neurochemical properties characteristic of a benzodiazepine receptor agonist may be important components, and contribute to the anticonvulsant property of G. elata.

The metabolic mechanism of C-14 labeled chitosan in mice

Kim, Kwang Yoon,Kim, Young Ho,Kim, Hee Kyung,Bom, Hee Seung,Kim, Ji Yeul,Yoshikazu Nishimura,Jkim, ung Woo,Oh, Chang Suck,Park, Ro Dong,Lee, Hyun Chul,Kang, Moon Il,Roh, Young Bok 한국키틴키토산학회 1998 한국키틴키토산학회지 Vol.3 No.1

Chitin is exists in the exoskeleton of crustaceans and chitosan can be obtained by deacetylation of chitin. As chitosan has a chelating characteristics, it was used radiostrontium chelator in the rats and mice. It also can be used as a healthy food and medicine. The purpose of the prsent study is to investigate the chitosan distribution and excretory route of 14C-chitosan in the animal body. 14C-chitosan was prepared and intravenously administered to the vein of mice and also intraorally ingested. The body distribution of chitosan was studied by autoradiography and the urinary excretion was counted. C-14 label chitosan was showed high distribution in the liver. And 10~20% of chitosan was excreted to the urine through kidney within few days. Chitosan was gathered into gromerulus in kidney and excreted from three hours. It was concluded that chitosan has no target organs and liver distribution is a sort of only passing route for the urinary excretion by way of kidney.

Effect of Calcium Phosphate Glass on Compressive Strength of Macroporous Hydroxyapatite Scaffold

Kim, Yeon Ung,Kim, Min Chul,Kim, Kyoung Nam,Kim, Kwang Mahn,Choi, Seong Ho,Kim, Chong Kwan,LeGeros, Racquel Z.,Lee, Yong Keun Trans Tech Publications, Ltd. 2005 Key Engineering Materials Vol.284 No.-

<P>This study presents the manufacture of macroporous hydroxyapatite scaffolds with a small amount of calcium phosphate glass powder as sintering additives. Hydroxyapatite slurry was prepared by suspending the hydroxyapatite and glass powder in water. Polyurethane sponge was used to produce highly macroporous scaffolds. The rheological characteristic of the slurry was measured to identify the effect of adding calcium phosphate glass powder into hydroxyapatite slurry. Sintered scaffolds could be repeatedly coated to improve mechanical properties. Scaffolds prepared by single and double replication cycle process were characterized by density, porosity and compressive strength measurements by increasing amount of the calcium phosphate glass powder to the hydroxyapatite slurry, viscosity by increased more than same amount of pure hydroxyapatite, and the capillary force was similar to pure hydroxyapatite slurry. The compressive strength of the macroporous hydroxyxapatite scaffold containing the calcium phosphate glass powder showed higher value than that of pure hydroxyapatite at single replication cycle. SEM demonstrated that the microstructure of the scaffold became denser with the introduction of the calcium phosphate glass powder. The pore struts were thicker as replication cycle was increased.</P>