• Journal of the Computational Structural Engineering Institute of Korea
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• v.36 no.3
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• pp.165-171
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• 2023

The rotary joint connecting the upper and lower structures of construction machinery and special vehicles transmits hydraulic pressure as the shaft and housing rotate, and multiple seals are assembled to prevent oil leakage into the oil flow channel. Because the seal material is rigid and difficult to assemble, we sought a method to assemble it after cutting. The shapes of the cutting surface are L-shaped and / shaped, and the leakage standard when hydraulic pressure is applied is the contact pressure generated on the cutting surface. The structure and material of the seal are composed of a double elastomer, and nonlinear contact structural analysis is performed when only the high-rigidity PE material is cut. Studies have shown that the shorter the cutting length, the better the leakage prevention and the higher the possibility of leakage to the bottom surface where NBR and PE come into contact rather than the top surface where the PE and the housing come into contact.

• Journal of Pharmaceutical Investigation
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• v.33 no.2
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• pp.145-149
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• 2003

Manufacturing facilities of the pharmaceuticals must meet certain level of the cleanness required so that foreign substances such as dust, moisture, heat, microorganism, or virus do not contaminate the product. In case of radiopharmaceuticals for medical treatment and diagnosis, not only should the operators and environment be protected from radiation but also need to be isolated from the foreign contaminant. Therefore, manufacturing facilities for radiopharmaceuticals must satisfy the design standards of both hot cell and clean room which are specified by GMP. However, standards of maintaining negative pressure for preventing spread of radioactive contaminant in isolated facilities conflict with the standards of maintaining positive pressure for keeping cleanness. To solve this problem, air pressure of hot cell was designed lower than in the adjacent area to meet standards of the radiation safety. To keep higher cleanness in certain part of the hot cell for filling, minimal relative positive pressure allows. In order to effectively maintain the cleanness that is required for production of Tc-99m generator, which takes 70% of whole demand of radiopharmaceuticals, the rooms placed in each side of production room are used as a buffer area and three lead hot cells are installed in production room. In this research, we established the appropriate engineered design concept for Tc-99m generator manufacturing facility, which satisfies both GMP cleanness standard for preventing particles, bacteria, other contaminants and the regulations of radiation safety for supervising and controlling the amount of radiation exposure and exhausted radioactivity. And the concept of multi-barrier buffer zones is introduced to apply negative air pressure for hot cell with first priority and to continue relative positive air pressure for clean room.

• Journal of dental hygiene science
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• v.15 no.1
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• pp.12-17
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• 2015

The purpose of this study was to evaluate the marginal and internal gap of metal coping fabricated using additive manufacturing (AM) group and subtractive manufacturing (SM) group by dental computer-aided design (CAD)/computer-aided manufacturing (CAM) systems. Twenty same cases of stone models of abutment teeth 16 by the universal numbering system were manufactured and scanned. Ten metal copings of control group were fabricated using SM and ten metal coping of experimental group were fabricated using AM. Marginal and internal gap of copings were measured using the silicone replica technique and digital microscope (${\times}140$). The data were analyzed using IBM SPSS 21.0 Statistical Software for independent samples t-test (${\alpha}=0.05$). Mean${\pm}$ standard deviation (SD) of marginal and internal gap total size of SM group was $101.00{\pm}40.33{\mu}m$ of AM group was $83.61{\pm}40.37{\mu}m$. Mean${\pm}$SD of marginal and internal gap total size of SM group was significantly greater than that of AM group (p<0.05). This study showed that AM metal copings had a better marginal and internal gap than SM metal copings.

• Design & Manufacturing
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• v.17 no.1
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• pp.20-26
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• 2023

Lab-on-a-disc is a circular disc shape of cartridge that can be used for blood-based liquid biopsy to diagnose an early stage of cancer. Currently, liquid biopsies are regarded as a time-consuming process, and require sophisticated skills to precisely separate cell-free DNA (cfDNA) and circulating tumor cells (CTCs) floating in the bloodstream for accurate diagnosis. However, by applying the lab-on-a-disc to liquid biopsy, the entire process can be operated automatically. To do so, the lab-on-a-disc should be designed to prevent blood leakage during the centrifugation, transport, and dilution of blood inside the lab-on-a-disc in the process of liquid biopsy. In this study, the main components of lab-on-a-disc for liquid biopsy are fabricated by injection molding for mass production, and ultrasonic welding is employed to ensure the bonding strength between the components. To guarantee accurate ultrasonic welding, the flatness of the components is optimized numerically by using the response surface methodology with four main injection molding processing parameters, including the mold & resin temperatures, the injection speed, and the packing pressure. The 27 times finite element analyses using Moldflow® reveal that the injection time and the packing pressure are the critical factors affecting the flatness of the components with an optimal set of values for all four processing parameters. To further improve the flatness of the lab-on-a-disc components for stable mass production, a quarter-disc shape of lab-on-a-disc with a radius of 75 mm is used instead of a full circular shape of the disc, and this significantly decreases the standard deviation of flatness to 30% due to the reduced overall length of the injection molded components by one-half. Moreover, it is also beneficial to use a quarter disc shape to manage the deviation of flatness under 3 sigma limits.

• Journal of the Korea Concrete Institute
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• v.18 no.6 s.96
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• pp.811-817
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• 2006

The primary purpose of this study is to estimate the guaranteed strength and construction quality of the combined high flowing concrete which is used in the slurry wall of underground LNG storage tank. The required compressive strength of this type of concrete become generally known as a non economical value because it is applied the high addition factor for variation coefficients and low reduction factor under water concrete. Therefore, after estimation of the construction quality and guaranteed strength in actual site work, this study is to propose a suitable equation to calculate the required compressive strength in order to improve its difference. Application results in actual site work are shown as followings. The optimum nix design proportion is selected that has water-cement ratio 51%, sand-aggregate ratio 48.8%, and replacement ratio 42.6% of lime stone powder by cement weight. Test results of slump flow as construction quality give average 616~634mm. 500mm flowing time and air content are satisfied with specifications in the rage of 6.3 seconds and 4.0% respectively. Results of strength test by standard curing mold show that average compressive strength is 49.9MPa, standard deviation and variation coefficients are low as 1.66MPa and 3.36%. Also test results by cored cylinder show that average compressive strength is 66.4MPa, standard deviation and variation coefficients are low as 3.64MPa and 5.48%. The guaranteed strength ratio between standard curing mold and cored cylinder show 1.23 and 1.32 in the flanks. It is shown that applied addition factor for variation coefficients and reduction factor under water concrete to calculate the required compressive strength is proved very conservative. Therefore, based on these results, it is proposed new equation having variation coefficients 7%, addition factor 1.13 and reduction factor 0.98 under water connote.

• Journal of Distribution Science
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• v.12 no.4
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• pp.41-46
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• 2014

Purpose - This study focused on providing strategic findings that make significant sense for companies that are looking for a future outsourcing strategy. The study analyzes the results of outsourcing in the information logistics systems field and verifies the results through experimental study of the performance delivered by logistics outsourcing types. Research design, data, and methodology - The study sample was assembled based on a random sampling method used to extract the initial 451 companies from a list of Korean distributors, wholesalers, and retailers. Following that sample process, 423 companies were confirmed by verifying their e-mail address and contacts (telephone and fax numbers), and were selected as initial research subjects. We reduced that number to 331 companies for the survey sample through telephone interviews in advance with the 423 companies that were targeted, in order to verify whether they are in the field of outsourcing of information logistics systems. The period of the survey extended from November 10, 2013 to January 10, 2014. The number of collected surveys totaled 181. We reviewed the contents of the survey responses, and reduced the number of research subjects to 175. In this study, we used a standard analysis to investigate whether there is a difference in distribution results based on different types of outsourcing information in the logistics system field and, through T-verification, we investigated whether the difference between distribution results in each group resulting from that standard analysis is statistically significant. Results - These results show that there is a difference in distribution outcome, based upon type of distribution outsourcing. In addition, we determined that they are meaningful results by confirming that, for usability and to improve the capabilities of a third-party logistics service supplier, both the choice of reasonable outsourcing types and the enhancement of various types of alliances are very important success factors. Taken together these study results, with a goal of enhancing the distribution capabilities of a Korean distributor, can be implemented to enhance management results achievable by supplying an information logistics system in the form of strategic outsourcing rather than in the form of simple outsourcing. In addition, the outcomes of logistics distributors in Korea that are using outsourcing in the logistics information systems field show high performance results in commercial endeavors in the following order: competitive, pre-competitive, non-competitive, and pro-competitive. Conclusions - This study focused on providing strategic findings. However, in the case of outsourcing in the field of information logistics systems of Korean distributors, there has been a focus on simple outsourcing rather than on strategic outsourcing; furthermore, there has been a concentration on non-competitive forms instead of pro-competitive forms, which could achieve better distribution results. This discussion is presented in more detail in the analysis results of this study.

• Journal of Korea Spatial Information System Society
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• v.10 no.4
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• pp.47-58
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• 2008

With the recent development of the ubiquitous computing technology, there are increasing interest and research in technologies such as sensors and RFID related to information recognition and location positioning in various ubiquitous fields. Especially, a standard specification was required for compatibility and interoperability in various RTLS(Real-Time Locating Systems) according to the development of RTLS to provide location and status information of moving objects using the RFID Tag. For these reasons, the ISO/IEC published the RTLS standard specification for compatibility and interoperability in RTLS. Therefore, in this paper, we designed and im plemented RTLS based on the spatial DSMS(Data Stream Management Stream) for efficiently managing and searching the incoming data stream of moving objects. The spatial DSMS is an extended system of STREAM(STanford stREam datA Manager) developed by Standford University to make various spatial operations possible. RTLS based on the spatial DSMS uses the SOAP(Simple Object Access Protocol) message between client and server for interoperability and translates client's SOAP message into CQL(Continuous Query Language) of the spatial DSMS. Finally, we proved the efficiency of RTLS based on the spatial DSMS by applying it for the staff location management service.

• Journal of the Korea Institute of Building Construction
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• v.19 no.6
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• pp.539-547
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• 2019

Recently, the international community signed a climate change agreement to prevent global warming. Yet currently, the fossil fuels have been widely used in to supply building energy for cooling and heating. The Green Building certification (G-SEED), an energy efficiency rating for new or existing buildings requires that buildings meet certain conditions. Insulation is used as a building material to reduce the energy supply to buildings and to improve the thermal insulation, and it accounts for more than 90% of the total heat resistance provided by the building surface components that meet the energy-saving design standards of new buildings. In this investigation, a performance evaluation study was conducted through an experimental study by directly extracting the foam polystyrene insulation on-site during the remodeling of a building that was in the range of 22~38 years old. Through tests, it was found that the thermal conductivity of the extrusion method insulation (XPS) was reduced by 48% and the compressive strength of XPS decreased by 36% compared to KS M 3808, which is the initial quality standard. For bead method insulation (EPS) with a thickness of 50mm, the thermal conductivity, the compressive strength, and flexural failure load were similar to the initial quality standard. Therefore, in the calculation of the primary energy requirement per unit area per year, the performance of bead method insulation can be estimated simply by considering the thickness of the insulation, while a correction factor that considers its performance deterioration should be applied when extrusion method insulation is used.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.11
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• pp.2442-2450
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• 2010

Using sensor devices applied to various objects will be needed wireless network that it is easy to install in them. Tiny devices configured to processor that bas comparatively low computing ability are inappropriate to use devices that are wireless LAN, etc. In result, network devices needed to not only have simple communication protocol, but have Plug and Play function that it works as soon as it connects without installing any device driver. it also will industrially have both low power and low cost because of mobility of it. From IEEE 802.11 standard, WPAN(Wireless Personal Area Network) included in LAN is being developed by WPAN WG(Working Group) on area with low power consumption and low complexity. In addition to, it is standardizing MAC and PRY of the standard that is expected to wirelessly communicate within 10m. WPAN will be used generally in the more near future because of both low power and low cost of Zigbee. In this paper we designed zigbee based user authentication module for a automotive smart-key system.

• Journal of Pharmaceutical Investigation
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• v.35 no.2
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• pp.117-122
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• 2005

After establishing improved HPLC analytical method of cefaclor in human plasma samples, a bioavailability study of cefaclor capsules was conducted according to the guidelines of Korea Food and Drug Administration (KFDA). The standard calibration curve using an HPLC with UV detector was constructed in a range of $0.0324{\sim}16\;{\mu}g/ml$. The 6% perchloric acid instead of 6% trichloroacetic acid was used to precipitate plasma protein. The HPLC chromatograms were precisely and accurately resolved when spiked with human plasma spiked with cefaclor and cephalexin (internal standard). Twenty healthy male Korean volunteers received two commercial cefaclor capsules, $Neocef^{\circledR}$ capsule (Jinyang Pharm. Co., Ltd) or $Ceclor^{\circledR}$ capsule (Lilly Korea. Co., Ltd.) at the 250 mg cefaclor in a $2{\times}2$ crossover study. There was a one-week washout period between the doses. Plasma concentrations of cefaclor were monitored for 8 hours after oral drug administration. $AUC_t$ the area under the plasma concentration-time curve from time zero to 8 hr (13 points), was calculated by the linear trapezoidal rule method. $C_{max}$ (maximum plasma drug concentration) and $T_{max}$ (time to reach $C_{max}$) were compiled from the plasma concentration-time data. Analysis of variance was carried out using logarithmically transformed $AUC_t$ and $C_{max}$. No significant sequence effect was found for all of the bioavailability parameters indicating that the cross-over design was properly performed. The 90% confidence intervals of the $AUC_t$ ratio and the $C_{max}$ ratio for $Neocef^{\circledR}/Ceclor^{\circledR}$ were $0.9049{\leq}{\delta}{\leq}1.226$, respectively. These values were within the acceptable bioequivalence intervals of 0.80-1.25. Thus, our study demonstrated the bioequivalence of $Neocef^{\circledR}/Ceclor^{\circledR}$ with respect to the extent of absorption.