• KIPS Transactions on Software and Data Engineering
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• v.3 no.6
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• pp.237-242
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• 2014

Current digital door lock systems are mainly designed for users' convenience, so they have weakness in security. Thus, this paper suggests a video digital doorlock system grouped with a relay device, a server, and a digital doorlock with a camera, sensors, and communication modules, which is detecting or recognizing objects approaching to the front of the door lock system and sending images and door-opening information to users' smart devices. Experiments showed that the suggested system has 96~98% recognition rate of approaching objects and requires 17.1~23.9 seconds for transmission on average, depending on network systems. Therefore, the system is thought to have enough capability for real time security response by monitoring the front area of the doorlock system.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.20 no.2
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• pp.35-39
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• 2014

One-way degassing valves are designed to allow pressure to be released from an air-tight package while preventing air from getting back into the package. Air, especially the oxygen ($O_2$) portion of air, can have negative effects on the package contents and its freshness. The most common application of the one-way degassing valve is for fresh roasted coffee. Demands of one-way degassing valves have been increasing with the high growth of global coffee market. In this study, we have developed one-way degassing valves for coffee and food packaging using ring type rubber disk, named SP valve. Its quality and performance was verified with test results to be equal with that of global top maker's product, Goglio valve. SP valves showed 820~1200 Pa of opening pressure, 10~50 Pa of closing pressure, 1.2~1.6 L/ min of flow rate. And, the SP valve applicable to ferment food packaging is expected to contribute to globalize Korean traditional food.

• Journal of Chest Surgery
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• v.30 no.4
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• pp.357-362
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• 1997

In vivo testings of the monoleaflet polymer valve were performed in seven dogs to prove its blood biocompatibility. The monoleaflet polymer valve used in this study was developed for short-term usage n the ventricular assist device. The frame and leaflet of the polymer valve were made of polyurethane. The inter-aortic valved conduit were implanted in four dogs and the ventriculo-atrial valved conduit was implanted in one dog. The ventricular assist devices with polymer valve were implanted in two dogs. The longest survival was 20 days. Main causes of death were bleeding and infection. To examine the blood compatibility, each blood sample was collected and RBC, WBC, hematocrit, hemoglobin, platelet and lactic acid dehydrogenase were analyzed. These studies thus far demonstrated that, with further development, a reliable and inexpensive polymer valve will be used in the ventricular assist device as short term usage.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.4
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• pp.401-407
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• 2014

In this paper, the effect of cohesive laws on the finite element analysis of crack propagation using cohesive elements is investigated through three-point bending and double cantilever beam problems. The cohesive elements are implemented into ABAQUS/Standard user subroutines(UEL), and the shape of cohesive law is varied by changing parameters in polynomial functions of cohesive traction-separation relations. In particular, crack propagation behaviors are studied by comparing load-displacement curves of the analysis models which have different shapes of cohesive laws with the same values of fracture energy and cohesive strength. Furthermore, the influence of the element size on crack propagation is discussed in this study.

• Applied Chemistry for Engineering
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• v.18 no.4
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• pp.330-336
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• 2007

In this study, new dinuclear chiral Co (salen) complexes bearing $BF_3$ have been synthesized and their properties as the asymmetric catalyst have been examined. The NMR, UV and ESCA analyses were performed to determine the structure of synthesized catalysts. Their catalytic activity and selectivity have been demonstrated for the asymmetric ring opening of various terminal epoxides by hydrolytic kinetic resolution technology. The easily prepared dimeric complexes exhibited very high enantioselectivity for the asymmetric ring opening of epoxides with $H_2O$ nucleophile, providing enantiomerically enriched terminal epoxides (> 99 %ee). The dimeric structured chiral salen showed remakablely enhanced reactivity and may be employed substantially lower loadings than its monomeric analogues, and in addition no racemization happened during the separation of product epoxides. The system described in this work is very efficient for the sinthesis of chiral epoxide and 1,2-diol intermediates.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.10B
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• pp.855-864
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• 2008

Optical link techniques compensating chromatic dispersion and nonlinear effects, which affect distortion of optical signals, generated in single mode fiber are investigated through computer simulation and design rule of these link techniques is proposed for implementation of wideband and long-haul WDM ($24{\times}40$ Gbps) transmission system. The optical link consist of dispersion management (DM) compensating the cumulated dispersion through total transmission line and optical phase conjugation in middle of total transmission line for compensating distorted signals by frequency inversion. DM schemes considered in this research are lumped DM and inline DM. It is confirmed that eye opening penalty (EOP) of overall WDM channels are more improved than those in WDM transmission systems with only optical phase conjugator (OPC), if DM is additionally applied to these systems. And, design rule in both DM schemes are proposed by using effective residual dispersion range. It is confirmed that inline DM is better than lumped DM in the improving EOP of total WDM channels and in effective residual dispersion range.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.10 s.241
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• pp.1361-1368
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• 2005

The structural and leakage integrity of steam generator tubes should be sustained all postulated loads with appropriate margin even if a crack is present. During the past three decades, for effective integrity evaluation, several limit load solutions have been used world-widely. However, to predict accurately load carrying capacities of specific components under different conditions, the solutions have to be modified by using lots of experimental data. The purpose of this paper is to propose a new burst pressure estimation scheme based on fracture mechanics analyses for steam generator tube with an axial or circumferential through-wall crack. A series of three dimensional elastic-plastic finite element analyses were carried out and, then, closed-form estimation equations with respect to both J-integral and crack opening displacement were derived through reference stress method. The developed engineering equations were utilized for structural integrity evaluation and the resulting data were compared to the corresponding ones fiom experiments as well as limit load solutions. Thereafter, since the effectiveness was proven by promising results, it is believed that the proposed estimation scheme can be used as an efficient tool for integrity evaluation of cracked steam generator tubes.

• Journal of the Institute of Convergence Signal Processing
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• v.10 no.3
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• pp.164-169
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• 2009

This paper proposes a road detection method using BP(Back-Propagation) neural network based on texture information of the each candidate road region segmented for satellite images. To segment the candidate road regions, the histogram-based binarization method proposed by N.Otsu is firstly performed and the neighboring regions surrounding road regions are then removed. And after extracting the principal color using the histogram of the segmented foreground, the candidate road regions are classified into the regions within ${\pm}25$ of the principal color. Finally, the road regions are segmented using BP neural network based on texture information of the candidate regions. The texture information in this paper is calculated using co-occurrence matrix and is used as an input data of the BP neural network. The proposed method is based on the fact that the road has the constant intensity and shape. The experiment demonstrated the validity of the proposed method and showed 90% detection accuracy for the various images.

• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.2
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• pp.198-204
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• 2012

Tracking and recognition of robots are required for the cooperation task of robots in various environments. In the paper, a tracking control system of moving robot using stereo image processing, code-book model and fuzzy controller is proposed. First, foreground and background images are separated by using code-book model method. A candidate region is selected based on the color information in the separated foreground image and real distance of the robot is estimated from matching process of depth image that is acquired through stereo image processing. The open and close processing of image are applied and labeling according to the size of mobile robot is used to recognize the moving robot effectively. A fuzzy tracking controller using distance information and mobile information by stereo image processing is designed for effective tracking according to the movement velocity of the target robot. The proposed fuzzy tracking control method is verified through tracking experiments of mobile robots with stereo camera.

• Korean Chemical Engineering Research
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• v.46 no.4
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• pp.769-776
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• 2008

The stereoselective synthesis of chiral terminal epoxide is of immense interest due to their utility as versatile starting materials as well as chiral intermediates. In this study, new chiral Co(salen) complexes bearing cobalt(II) chloride, iron(III) chloride and zinc(II) nitrate have been synthesized and characterized. The mass and EXAFS spectra provided the direct evidence of formation of complex. Their catalytic activity and selectivity have been demonstrated for the asymmetric ring opening of terminal epoxides such as styrene oxide and phenylglycidylether by hydrolytic kinetic resolution technology and for the synthesis of glycidyl buthylate. The easily prepared complexes exhibited very high enantioselectivity for the asymmetric ring opening of epoxides with $H_2O$ nucleophile, providing enantiomerically enriched terminal epoxides (>99% ee). The newly synthesized chiral salen showed remakablely enhanced reactivity with substantially low loadings. The system described in this work is very efficient for the sinthesis of chiral epoxide and 1,2-diol intermediates.