• 한국컴퓨터정보학회논문지
• /
• 제10권2호
• /
• pp.199-204
• /
• 2005

인터넷 사용이 급속히 확산되면서 많은 기업들이 전자상거래를 적극적으로 도입하고 있으며 시장규모도 급속도로 증가하고 있다. 그러나 전자상거래에 대한 연구성과는 그 중요성과 사회적 관심에 비해 매우 미약한 실정이다. 특히 고객 요구사항은 온라인 구매의향에 많은 영향을 미칠 수 있으므로 이에 대한 정확한 이해가 선행되어야만 할 것이다. 본 연구는 전자상거래에서 중요시되는 구매의향에 대한 성공요인을 분석함으로써 인터넷 쇼핑몰의 설계 운영, 전략수립 등에 시사점을 제공하기 위함이다. 연구결과 가격 및 사용자편리, 쇼핑몰 배송 등에 대한 신뢰, 속도 및 오류방지가 쇼핑물 구매의향에 유의한 영향을 미치는 것으로 판명되었다.

• Journal of Pharmaceutical Investigation
• /
• 제34권4호
• /
• pp.275-281
• /
• 2004

We have studied the effect of polarity, current density, current duration, crosslinking density, swelling ratio, and permeation enhancers on the transdermal flux of ketoprofen from acrylamide hydrogel. Hydrogel was prepared by free radical crosslinking polymerization of acrylamide. Drug loading was made just before transport experiment by soaking the hydrogel in solution containing drug. In vitro flux study using hairless mouse skin was performed at $36.5^{\circ}C$ using side-by-side diffusion cell, and the drug was analysed using HPLC/UV system. The result showed that, compared to passive flux, the total amount of drug transported increased about 18 folds by the application of $0.4\;mA/cm^2$ cathodal current. Anodal delivery with same current density also increased the total amount of drug transported about 13 folds. It seemed that the increase in flux was due to the electrorepulsion and the increase in passive permeability of the skin by the current application. Flux increased as current density, the duration of current application and loading amount (swelling duration) increased. As the cross linking density of the hydrogel increased, flux clearly decreased. The effect of hydrophilic enhancers (urea, N-methyl pyrrolidone, Tween 20) and some hydrophobic enhancers (propylene glycol monolaurate and isopropyl myristate) was minimal. However, about 3 folds increase in flux was observed when 5% oleic acid was used. Overall, these results provide some useful information on the design of an optimized iontophoretic delivery system of ketoprofen.

• Advances in materials Research
• /
• 제11권2호
• /
• pp.165-170
• /
• 2022

Acrylic resin or polymethylmethacrylate (PMMA) is one of the most attractive materials to be used for dental appliances manufacturing. It has been introduced as a biomaterial during the last century. This study aims to evaluate the compounds absorption and release through acrylic resin to be used for drug delivery as well. The study specimens were 10 pieces of heat-cured clear acrylic resin with dimensions of 10 × 10 × 2 mm. The specimens were dipped in methylene blue solution at a powder-water ratio of 1:20 for 5 days. The samples were removed and dipped in 5 ml distilled water vials for 24 hours. Then the specimens were replaced into new 5 ml vials and the process lasted for 4 days. The extracted solutions were analyzed by the visible light spectroscopy for absorbance. The statistical results showed a gradual increase in stain release from day 1 to day 4 with a significant difference between day 1 and day 4 solutions. The study showed that PMMA resin is able to absorb and release some compounds constantly and the absorption drug-loading technique is applicable to this material.

• 대한안전경영과학회지
• /
• 제25권1호
• /
• pp.15-21
• /
• 2023

In modern society, the delivery service market has grown explosively due to rapid changes in social structure and the recent COVID-19 pandemic. Therefore, various problems such as injury to workers and an increase in human accidents are occurring due to the loading and unloading of parcels. In order to solve this problem, domestic company n is developing a "robot-based cargo loading and unloading system". In developing a new technology system, quantitative reliability targets should be set for efficient operation and development. In this paper, reliability analysis was conducted through field data for the pneumatic gripper of the "robot-based cargo loading system". The reliability of the failure data was analyzed to estimate the distribution parameters and MTTF. Random data was derived for the probability of occurrence of a failure with the estimated value. By repeating the simulation to predict the number and year of failures according to the estimated parameters of the probability distribution, it was proposed as a method that reflects realistic probabilities rather than calculating with simple arithmetic using the average MTTF previously used in the field.

• Journal of Pharmaceutical Investigation
• /
• 제41권6호
• /
• pp.323-329
• /
• 2011

In order to develop new protein carrier replacing poly(DL-lactic acid-co-glycolic acid) (PLGA) microspheres, succinylated pullulan acetate (SPA) was investigated to fabricate a long term protein delivery carrier. SPA microspheres loaded with lysozyme (Lys) as a model protein drug were prepared by a water/oil/water (W/O/W) double emulsion method. An acidity test of SPA copolymers after hydrolysis was performed to estimate the change of protein stability during releasing proteins from the microspheres. There was no pH change of SPA copolymers, but pH of PLGA polymers after hydrolysis was significantly decreased to around pH 2, indicating that the long-term stability of proteins released from SPA microspheres can be guaranteed. Loading efficiency of proteins into SPA microspheres was three times higher than those into conventional PLGA microspheres, indication of inducing stronger charge interaction between proteins and succinyl groups in SPA microspheres. Although initial burst behaviors were monitored in Lys-loaded SPA microspheres due to relatively strong hydrophilic succinyl segments in SPA microspheres, initial burst issues would be circumvented if the ratio of charge density of succinyl moieties and hydrophobic acetate groups is harmonically controlled. Therefore, in this study, a new attempt of protein delivery system was made and functional SPA was successfully confirmed as a new protein carrier.

• Journal of Pharmaceutical Investigation
• /
• 제39권6호
• /
• pp.437-443
• /
• 2009

To develop a topical bioadhesive formulation of clotrimazole for enhanced transdermal delivery, hydroxypropyl methylcellulose gel containing permeation enhancer was formulated and permeation studies were carried out. The release characteristics of the drug from the gel formulation were examined according to the receptor medium, drug concentration, and temperature. The rate of drug release from the gel increased with increasing drug concentration and temperature. The activation energy (Ea) of drug permeation, which was calculated from the slope of log P versus 1/T plots, was 14.41kcal/mol for a 1%(w/w) loading dose. The enhancer, such as saturated, unsaturated fatty acids, pyrrolidones, propylene glycol derivatives, glycerides, and non-ionic surfactants, were incorporated onto the gels to increase the amount of drug permeation into the skin. Among the enhancers used, polyoxyethylene 2-oleyl ether showed the highest level of enhancement. These results show that clotrimazole gels containing polyoxyethylene 2-oleyl ether could be used for the enhanced transdermal delivery of clotrimazole.

• Macromolecular Research
• /
• 제15권7호
• /
• pp.646-655
• /
• 2007

To achieve targeted drug delivery for chemotherapy, a ligand-mediated nanoparticulate drug carrier was designed, which could identity a specific receptor on the surfaces of tumor cells. Biodegradable poly(ethylene oxide)/poly$({\varepsilon}-caprolactone)$ (PEG/PCL) amphiphilic block copolymers coupled to biotin ligands were synthesized with a variety of PEG/PCL compositions. Block copolymeric nanoparticles harboring the anticancer drug paclitaxel were prepared via micelle formation in aqueous solution. The size of the biotin-conjugated PEG/PCL nanoparticles was determined by light scattering measurements to be 88-118 nm, depending on the molecular weight of the block copolymer, and remained less than 120 nm even after paclitaxel loading. From an in vitro release study, biotin-conjugated PEG/PCL nanoparticles containing paclitaxel evidenced sustained release profiles of the drug with no initial burst effect. The biotin-conjugated PEG/PCL block copolymer itself evidenced no significant adverse effects on cell viability at $0.005-1.0{\mu}g/mL$ of nanoparticle suspension regardless of cell type (normal human fibroblasts and HeLa cells). However, biotin-conjugated PEG/PCL harboring paclitaxel evidenced a much higher cytotoxicity for cancer cells than was observed in the PEG/PCL nanoparticles without the biotin group. These results showed that the biotin-conjugated nanoparticles could improve the selective delivery of paclitaxel into cancer cells via interactions with over-expressed biotin receptors on the surfaces of cancer cells.

• Bulletin of the Korean Chemical Society
• /
• 제32권3호
• /
• pp.867-872
• /
• 2011

For the prolonged delivery and sustained release rates of low molecular weight drugs, poly(lactic-co-glycolic acid) (PLGA) microparticles containing the drug SKL-2020 have been investigated. On increasing polyvinyl alcohol (PVA) concentration (from 0.2% to 5%), the size of microparticles decreased (from $48.02{\mu}m$ to $10.63{\mu}m$) and more uniform size distribution was noticeable due to the powerful emulsifying ability of PVA. A higher drug loading (from 5% to 20%) caused a larger concentration gradient between 2 phases at the polymer precipitation step; this resulted in decreased encapsulation efficiency (from 34.19% to 25.67%) and a greater initial burst (from 61.71% to 70.05%). SKL-2020-loaded PLGA microparticles prepared with different fabrication conditions exhibited unique release patterns of SKL-2020. High PVA concentration and high drug loading led to an initial burst effect by rapid drug diffusion through the polymer matrix. Since PLGA microparticles enabled the slow release of SKL-2020 over 1 week in vitro and in vivo, more convenient and comfortable treatment could be facilitated with less frequent administration. It is feasible to design a release profile by mixing microparticles that were prepared with different fabrication conditions. By this method, the initial burst could be repressed properly and drug release rate could decrease.

• 한국구조물진단유지관리공학회 논문집
• /
• 제14권2호
• /
• pp.137-144
• /
• 2010

팽이기초에 대한 일본과 국내에서 현재까지 공통적으로 연구되고 있는 것은 팽이기초의 현장재하실험에 대한 지지력과 침하량에 주목되어 있다. 그러나 팽이기초에서 선행되어야할 연구는 공법 자체가 상재하중을 하부에 어떠한 원리로 전달되는 지에 대한 분석이 수행되어야 한다. 이에 본 연구에서는 일본에서 개발된 Top-Base Foundation과 국내에서 개발된 부양형 팽이기초의 응력전달 메커니즘을 수치해석 및 실내모형실험을 통하여 분석하였다. 팽이기초의 하중전달 메커니즘을 분석한 결과 상재하중에 대한 팽이기초 자체의 하중저감 분담률은 주로 팽이기초와 쇄석사이에서 발생하는 주면마찰력이 가장 크게 나타났다. 또한, 팽이기초의 내부응력분산효과를 포함한 Top-Base Foundation의 총 응력분산각은 $41.8^{\circ}$이며, 부양형 팽이기초의 총 응력분산각은 $44.5^{\circ}$로 산정되었다.

• 대한교통학회지
• /
• 제26권2호
• /
• pp.57-67
• /
• 2008

도시내부에서 발생하는 화물자동차의 이동에 따라 도심상업지역에서는 노상 하역공간(loading zone)이 반드시 필요하다. 그렇지만, 현재 대도시의 도심상업지역의 경우는 하역공간의 설치미비로 인하여 화물자동차들은 마땅한 조업공간이 없어 노상에서 불법주정차 행위를 하고 있는 실정이다. 이로 인하여 도심교통의 장애를 야기하는 하나의 원이 되었으며, 그로 인한 혼잡은 심각한 수준에 도달해 있는 실정이다. 따라서, 본 연구에서는 이러한 문제점을 다소나마 해결할 수 있도록 노상하역공간의 정비방안을 살펴보고, 부산의 도심상업지역인 서면지역 일대를 대상으로 하여 노상하역주차 특성을 면밀히 고찰함으로써 그 적용가능성도 확인할 수 있었다. 본 연구에서 노상 하역공간의 정비는 규모 즉, 조업을 행할 수 있는 주 정차 베이(bay)의 개수 추계와 함께 이들의 적절한 배치장소를 모색하는 것이다. 규모적 측면에서의 주 정차 베이 수는 조업차량의 도착율 및 서비스율에 기초한 대기행렬의 적용을 통하여 산출 할 수 있었으며, 배치장소의 결정은 화물운반에 대한 저항함수를 정식화함으로써 최소 저항이 되는 위치를 산정할 수 있었다.