• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2011.06a
• /
• pp.1491-1492
• /
• 2011

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2011.06a
• /
• pp.1011-1012
• /
• 2011

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2009.10a
• /
• pp.188-189
• /
• 2009

AAO 템플레이트 기공 안에 기상 중합 방식을 이용하여 Poly(3,4-ethylenedioxythiophene) 전도성 나노 튜브를 제조하였다. PEDOT 나노튜브는 나노 단위의 직경과 마이크로 단위의 길이로 조절이 자유로우며 잘 정렬된 구조를 갖는다. PEDOT 나노 튜브의 전도도는 2000 S/cm로써 박막으로 제조된 것에 비해 향상되었으며, XPS, TEM, SEM와 SPM을 통해 형태 및 특성을 확인하였다.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2009.10a
• /
• pp.190-191
• /
• 2009

최근 환경오염물질을 제거하기 위한 방법으로 광촉매를 이용한 기술들이 다양하게 활용되고 있다. 본 연구에서는 높은 비표면적을 갖는 광촉매를 제조하기 위해, 전기화학적인 방법인 양극 산화법을 사용하여 기지 Ti 금속 표면에 기공성 형태의 광촉매용 $TiO_2$를 제조하고, 염료분해 반응을 통해 광촉매의 효율을 조사하였다. 또한 염료분해 효율을 높이기 위해 $H_3(BO_3)_3$를 첨가하여 염료분해 반응에 미치는 영향에 대해 조사하였다.

• Bulletin of the Korean Chemical Society
• /
• v.20 no.11
• /
• pp.1340-1344
• /
• 1999

The electrochemical behavior of oxide layers on aluminium was studied using electrochemical impedance spectroscopy. Impedance spectra were taken at a compact and a porous oxide layer of Al. The anodic films on Al have a variable stoichiometry with gradual reduction of oxygen deficiency towards the oxide-electrolyte interface. Thus, the interpretation of impedance spectra for oxide layers is complicated, with the impedance of surface layers differing from those of ideal capacitors. This layer behavior with conductance gradients was caused by an inhomogeneous dielectric. The frequency response cannot be described by a single RC element. The oxide layers of Al are properly described by the Young model of dielectric constant with a vertical decay of conductivity.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.15 no.1
• /
• pp.308-322
• /
• 1991

A set of experiments of Counter-Current Flow Limit(CCFL or Flooding) was performed to improve the drawbacks of Wallis' Correlation which neglects the effects of channel size, channel length, injection method and the boundary conditions at the inlet of liquid and gas phase. In these experiments using water and air, the followings were found ; (i) The effects of channel size and length were quite significant. In large tubes(D>20mm), the flooding front occurred at the bottom of the channel and when the gas flow increased the front moved upward ; however, in small tubes(D<20mm), there were no upward movement of flooding front and the flooding just occurred at the liquid inlet. (ii) The effect of water inlet device was not as significant as that of channel length though the inlet boundary conditions could affect the flow development and flooding afterward. (iii) Once the flooding front reached the inlet of water injection device, an newly reduced flow condition was set up and resulted in another flooding corresponding to the new condition.

• KSBB Journal
• /
• v.10 no.1
• /
• pp.105-112
• /
• 1995

The fiber-optic biosensor using enzyme-immobilized Langmuir-Blodgett film is developed fort the measurement of ethanol. The enzyme, alcohol dehydrogenase, is immobilized at the molecular level on the arachidic acid monolayer using Langmuir-Blodgett film technique. Based on the ordered multisubstrate mechanism, the immobilized enzyme kinetics is investigated. The optical sensing system is proposed, and sensor signal is proportional to ethanol concentration and is related wish the number of enzyme layers. As the number of deposited LB film layer increases up to 20 1ayers, the high ethanol concentration of 45mM can be measured without the saturation of signal. Surface pressure-area isotherm is measured for the three-different charged-lipids. Arachidic acid is the most suitable for the adsorption of alcohol dehydrogenase based on electrostatic force.

• Advances in pediatric surgery
• /
• v.13 no.1
• /
• pp.52-60
• /
• 2007

Pediatric laparoscopic appendectomy is controversial particularly in complicated appendicitis. We evaluated the outcomes of laparoscopic appendectomy (LA) and open appendectomy (OA) in simple appendicitis and complicated appendicitis respectively. Since June 2004, initial LA has been our policy in all appendicitis including complicated ones. A total of 160 patients were included in this study, consisting of 80 OA (August 2001 - August 2003) and 80 LA (June 2004 - June 2006). We compared the operating time, the length of hospital stay, the length of antibiotics use, and the postoperative complications between LA and OA. In simple appendicitis (73), there were no differences between LA and OA. However in the 87 patients with complicated appendicitis, the operating time was longer in LA (64.8 min vs. 50.2 min) but the length of hospital stay was shorter in LA than OA (8.5 days vs. 9.6 days). There was one complication in simple appendicitis group and six in complicated appendicitis group (3 cases in LA, 3 cases in OA). There was no difference in the results of LA versus OA in simple appendicitis. Therefore for simple appendicitis, LA is recommended in consideration of the cosmetic effect (fewer scar). In complicated appendicitis, early discharge was an advantage and there were no differences in complications in LA despite a longer operative time. So we conclude LA can be considered as the first choice of treatment for all pediatric appendicitis including complicated appendicitis. To confirm our impressions, more well controlled randomized prospective studied need to be done.

• Journal of the Korean GEO-environmental Society
• /
• v.14 no.9
• /
• pp.57-65
• /
• 2013

Carbonate sands can be crushed under low confining pressure to achieve high compressibility. So particle crushing has significant influence on characteristics of strength and deformation. Trial embankment and hydrotest are conducted on Sabkha layer, consisting of carbonate sand to build tank structure. In this paper the settlement behavior was analyzed from each test. Particle crushing happened from 80 to 170kPa stress under compression test, and calcium was detected from chemical test. The test result came out Sabkha soil was very weak and easy to be crushing. About trial embankment test, particle crushing was not happen, and then extinction of pore water pressure and settlements were finished just during 2 days. On the other hand, the long-term settlement was happened in hydrotest. So the two test results did not correspond to each other. If loading stress is higher than yielding stress, instant settlement and secondary compression settlement are happened as a result of the particle crushing.

• Advances in pediatric surgery
• /
• v.2 no.1
• /
• pp.8-16
• /
• 1996

Laparoscopic appendectomy is relatively well-established as an alternative to conventional open appendectomy by many laparoscopic surgeons. However, experience in the pediatric population remains limited. Over a period of 2 years, a total of 155 pediatric patients with acute appendicitis or complicated appendicitis were studied to compare laparoscopic and open appendectomies in childhood. Laparoscopic appendectomy was attempted in 49 patients and completed in 48 patients(98.0%). Open appendectomy was performed in 107 patients. The severity of disease, age, and male to female ratio were similar in both groups. The operation time was shorter in the laparoscopic group than open group but the difference was not significant statistically($43.7{\pm}11.3$ minutes versus $49.0{\pm}21.4$ minutes, p=0.066). In the laparoscopic group, the mean duration of surgery for the former half patients was significantly longer than for the latter half($49.6{\pm}9.2$ minutes versus $38.1{\pm}10.3$ minutes, p=0.001). The mean number of doses of analgesia required postoperatively was significantly less in patients undergoing laparoscopic appendectomy($2.4{\pm}1.8$ versus $3.3{\pm}2.5$, p=0.021). There were only 2(4.2%) wound infections after laparoscopic appendectomy compared with 10(9.3%) complications including 7 wound infections, 1 intestinal obstruction, and 2 pulmonary complications after open appendectomy, but the difference was not significant(p=0.614). Patients undergoing laparoscopic appendectomy had a shorter period of hospitalization($3.2{\pm}2.2$ days versus $6.4{\pm}1.6$ days. p=0.001). The present study suggests that laparoscopic appendectomy shortens operating time and hospital stay with diminished postoperative pain. Laparoscopic appendectomy in children offers advantages over open appendectomy as noted in adults. The authors consider laparoscopic appendectomy to be the reasonable alternative to open appendectomy in children.