• Journal of the Korean Institute of Gas
• /
• v.21 no.4
• /
• pp.70-75
• /
• 2017

This paper presents the FEM analysis results on the deformation behavior safety of automatic cut-off horizontal and conventional vertical gas valves. Based on the FEM analysis, the primary maximum deformation of $4.4{\mu}m$ was formed on the right end side of a valve body when the internal gas pressure was supplied on the screw port and gas discharge port of an automatic cut-off horizontal gas valve. And the secondary maximum deformation of $2.9{\mu}m$ was formed on the end side of safety valve port. This small deformation of an automatic cut-off horizontal gas valve is strongly related to the balanced design of a horizontal gas valve main body, which is composed of a screw part, gas outlet port, port for a stem and spindle shaft assembly, and safety valve port. But, the primary maximum deformation of 0.076mm was formed on the upper part of a conventional automatic cut-off vertical gas valve when the internal gas pressure was supplied on the screw port and gas discharge port. And the secondary maximum deformation of 0.055mm was formed on the left end side of a gas outlet port. This may effect on the sealing clearance of o-ring that is inserted on the groove of an automatic cut-off unit. Thus, this paper recommends an automatic cut-off horizontal gas valve compared with that of a conventional gas valve for a gas leakage free mechanism of a LPG cylinder valve.

• Journal of the Korean Electrochemical Society
• /
• v.4 no.4
• /
• pp.172-175
• /
• 2001

Nanophase catalyst layer for direct methanol fuel cell has been fabricated by magnetron sputtering method. Catalyst metal targets and carbon were sputtered simultaneously on the Nafion membrane surface at abnormally higher gas (Ar/He mixture) pressure than that of normal thin film processing. They could be coated as a novel structure of catalyst layer containing porous PtRu or Pt and carbon particles both in nanometer range. Membrane electrode assembly made with this layer led to a reduction of the catalyst loading. At the catalyst loading of 1.5mg $PtRu/cm^2$ for anode and 1mg $Pt/cm^2$ for cathode, it could provide $45 mW/cm^2$ in the operation at 2 M methanol, 1 Bar Air at 80"C. It is more than $30\%$ increase of the power density performance at the same level of catalyst loading by conventional method. This was realized due to the ultra fine particle sizes and a large fraction of the atoms lie on the grain boundaries of nanophase catalyst layer and they played an important role of fast catalyst reaction kinetics and more efficient fuel path. Commercialization of direct methanol fuel cell for portable electronic devices is anticipated by the further development of such design.

• Membrane Journal
• /
• v.20 no.1
• /
• pp.29-39
• /
• 2010

This study focuses on the modeling of DMFC to predict the characteristics and to improve its performance. This modeling requires deep understanding of the design and operating parameters that influence on the cell potential. Furthermore, the knowledge with reference to electrochemistry, transport phenomena and fluid dynamics should be employed for the duration of mathematical description of the given process. Considering the fact that MEA is the nucleus of DMFC, special attention was made to the development of mathematical model of MEA. Multiscale modeling is comprised of process modeling as well as a computational fluid dynamics (CFD) modeling. The CFD packages and process simulation tools are used in simulating the steady-state process. The process simulation tool calculates theelectrochemical kinetics as well as the change of fractions, and at the same time, CFD calculates various balance equations. The integrated simulation with multiscal modeling explains experimental observations of transparent DMFC.

• Korean Journal of Oriental Medicine
• /
• v.16 no.3
• /
• pp.85-93
• /
• 2010

The aim of this review is to investigate clinical studies on oriental medicine treatment for obesity in Korean literature and to propose for the better method of clinical studies in order to seek more effective treatment. Electric searches were performed with NDSL, National assembly library, RISS4U, DBPIA, KISS, KMBASE, KoreaMed, Korean traditional knowledge portal and Oasis. Also, 21 major journals associated with oriental medicine in Korea were searched manually. Eighty three studies were included and analyzed in terms of study design, subjects, interventions, results and evaluation of safety. The numbers of controlled, non-controlled and case studies are respectively 26(31%), 43(52%) and 14(17%). Studies using sample size less than 30 accounts for 49% and studies using subjects diagnosed as obese or overweight by specific criteria were 35(42%). Studies which used more than 2 interventions or co-interventions were 76%. Clinical studies which used single herbal medicine were few and clinically studied single herbal medicine were limited to ephedra. More than half of 83 studies were studied for 8 weeks and less. 12% of 69 studies(except case studies) were not statistically analyzed and studies which evaluated safety of intervention were 22(27%) and reported adverse events were 9(11%). To improve the quality of clinical studies on oriental medicine treatment for obesity, studies need to use restricted number of interventions and subjects need to specifically diagnosed as overweight or obese. In addition, various kinds of single herbs need to be clinically studied based on experimental studies and herbalogy.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.11
• /
• pp.130-135
• /
• 2019

This study performed the quality improvement of a red dot sight for a 40 mm grenade launcher through parallax reduction. The red dot sight cited in this study is currently in mass production for military use as a non-weapon system. While the red dot sight's parallax currently meets requirements, slightly greater error was observed on the outside of effective optical area of the reflection lens compared to other sights. Parallax is easily affected by eye movement, which can result in aiming error. To improve the red dot sight's quality, this study analyzed why parallax is observed in the effective optical area of the reflection lens and how to reduce it. As a result, the red dot sight demonstrated lower parallax error using the new optical system design with an increased reflection lens thickness and modified components configuration related to the reflection lens assembly. Parallax was calculated and simulated by using a particular program to verify that it decreased. This improvement for the 40 mm. grenade launcher red dot sight more than satisfies requirements, offers advanced capabilities for users, and as a result, successful operation carryout.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.10 no.2 s.21
• /
• pp.35-39
• /
• 2004

Ship structures are basically an assembly of plate elements and the load-carrying capacity or the ultimate strength is one of the most important criteria for safety assessment and economic design. Also, Structural elements making up ship plated structures do not work separately, resulting in high degree of redundancy and complexity, in contrast to those of steel framed structures. To enable the behavior of such structures to be analyzed simplifications or idealizations must essentially be made considering the accuracy needed and the degree of complexity of the analysis to be used On this study, to investigate effect of modeling range, the finite element method are used and their results are compared varying the analysis ranges. The model has been selected from bottom panels of merchant ship structures. For FHA, three types of structural modeling are adopted in terms of the extent of the analysis. The purpose of the present study is to numerically calculate the characteristics of ultimate strength behavior according to the analysis ranges of stiffened panels subject to uniaxial compressive loads.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2015.05a
• /
• pp.768-770
• /
• 2015

We performed integration and standardization of the omics data related agriculture. To do this, we requires progressed computational methods and bioinformatics infrastructures for integration, standardization, mining, and analysis. It makes easier biological knowledge to find. we potentialize registration a row and processed data in NABIC (National Agricultural Biotechnology Information Center) and its processed analysis results were offered related researchers. And we also provided various analysis pipelines, NGS analysis (Reference assembly, RNA-seq), GWAS, Microbial community analysis. In addition, the our system was carried out based on the design and build the quality assurance in management omics information system and constructed the infrastructure for utilization of omics analyze system. We carried out major improvement quality of omics information system. First is Improvement quality of registration category for omics based information. Second is data processing and development platform for web UI about related omics data. Third is development of proprietary management information for omics registration database. Forth is management and development of the statistics module producers about omics data. Last is Improvement the standard upload/ download module for Large omics Registration information.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.38 no.12
• /
• pp.1223-1231
• /
• 2010

The design is presented for a SATCOM antenna capable of simultaneous multi-band (X/Ku/Ka-Band) communications without replacement of feed horns or change of other parts in the application as a ground satellite terminal for large data transfer. The antenna is the offset configuration and consists of a dual-band(X/Ka-band) feed horn, a single-band(Ku-band) feed horn, a frequency selective surface(FSS) sub-reflector and a parabolic main-reflector. The antenna has a main reflector defining a prime focus and a frequency selective surface sub-reflector defining an image focus. A dual-band feed and a single-band feed are provided at each of the prime focus and image focus. The antenna is designed using 3D EM simulator and the gains measured in X/Ku/Ka-band of the complete antenna assembly is more than 31.6dBi, 36.8dBi, 40.8dBi, and the cross polarization is 21.7dB, 26.6dB, 25.2dB, respectively.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.9
• /
• pp.1161-1166
• /
• 2010

Tapered roller bearings are core components of rotating machine parts and are simultaneously subjected to axial and radial loads. Life-shortening effect was particularly evident in the case of tapered roller bearings used in the input and output shafts of transmission; this shortening of life was a result of excessive axial pre-load, which is common in the transmission assembly line. In this study, we derived an equation for evaluating the life of tapered roller bearings subjected to excessive pre-load by using accelerated life test data. The DOE(Design Of Experiment) method and FEA(Finite Element Analysis) was used for determining the condition for performing an accelerated life test. This equation for evaluating the service life of the bearings was derived by analyzing the Weibull distribution of the test results. Using the derived equation the life evaluated was 6-7 times longer than that evaluated by the conventional $L_{10}$ bearing-life equation. The results of this study will be helpful in predicting the life of tapered roller bearings subjected to excessive pre-load and in designing reliable rotating machines.

• Journal of the Korean Vacuum Society
• /
• v.16 no.5
• /
• pp.388-396
• /
• 2007

KSTAR (Korea Superconducting Tokamak Advanced Research) current lead system (CLS) has a role to interconnect magnet power supply (MPS) in room temperature (300 K) and superconducting (SC) bus-line, electrically. For the first plasma experiments, it should be assembled 4 current leads (CL) on toroidal field (TF) current lead box (CLB) and 14 leads on poloidal field (PF) CLB. Two current leads, with the design currents 17.5 kA, and SC bus-lines are connected in parallel to supply 35 kA DC currents on TF magnet. Whereas, it could supply $20\;{\sim}\;26\;kA$ to each pairs of PF magnets during more than 350 s. At the cold terminals of the leads, there are joined SC bus-lines and it was constructed helium coolant control system, aside from main tokamak system, to protect heat flux through current leads and enhanced Joule heat due to supplied currents. Throughout the establishment processes, it was tested the high vacuum pumping, helium leak of the helium lines and hardwares mounted between the helium lines, flow controls for CL, and liquid nitrogen cool-down of possible parts (current leads, CL helium lines, and thermal shield helium lines for CLB), for the accomplishment of the required performances.