• Magazine of the Korea Concrete Institute
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• v.7 no.1
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• pp.117-125
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• 1995

Bond test was carried out to assess the effect of several variables on bond characteristics between reinforcing bar and concrete. Key variables are concrete compressive strength($f_c$'=340, 460, 6513, 904kg/$cm^2$), concrete cover (25, 38, 51, 105, IlOmm), and bar diameter(Dl3 and D22). Confining effect and bar spacing are not taken into account. Thirty-two specimens subjected to uniaxial tension were tested under hypothesis uniform bond stress distribution along the reinforcing bar embeded in concrete. Failure mode was examined and local bond stress versus slip relationship diagrams were represented to show effect of the above variables, also test results(u1timate bond stress) were compared with bond and development provisions of the ACI Building Code(AC1 318-89) and proposed equations from previous research. According to analysis, borld stress and ultimate bond stress increased although compressive strength increased beyond the ACI Building Code upper limit. Therefore in calculating development length. compressive strength effect(exceeding 700kg /$cm^2$) should be accounted.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.3
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• pp.82-87
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• 2013

In this work, the 1L grade integrated metal DOC/DPF filter that can install in engine manifold position was developed to investigate the effect of platinum-coating amount of filter on the improvement of filter activation temperature and reduction of particulate matter (PM). This filter was installed in 2.9L CI engine which meets the EURO-4 emission regulation. Tests for PM reduction efficiency of filter were conducted under ND-13 mode with full-load test condition. It was revealed that the time to reach the activation temperature of metal filter ($280^{\circ}C$) was shorter as the amount of platinum-coating increased. This short activation time can be helpful for the reduction of CO and HC emissions during cold start condition. At the same time, PM reduced as the coating amount increased. The reduction percentage of $DOC_{40}$, $DOC_{20}$, and $DOC_0$ were 96.7% (2.34 mg/kW'h), 95.1% (3.47 mg/kW'h), and 94.5% (3.69 mg/kW'h) compared to previous result (71.4 mg/kW'h), respectively.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.5
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• pp.13-18
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• 2017

In this work the augmented safety of Type 4 composite vessel in accordance with uniform-stress design has been demonstrated through a series of burst tests and structural analyses. For this end, three sample vessels were used: (1) designed as guided by the isotensoid dome theory (called iso-dome cylinder); (2) with dome longer compared to uniform-stress design (called prolate cylinder); and (3) with dome wider than uniform-stress design (called oblate cylinder). Structural analyses have been performed using ABAQUS finite element code based on the periodic symmetry to circumferential direction. As a result, the maximum stresses are induced around the bodies of all three cylinders. However, the analyses, with the assumption of possible defect demonstrate that the maximum stresses are induced around the dome knuckles for the prolate and the oblate cylinders. The results of the burst tests for the three cylinders show that the burst initiates from the cylinder body of the iso-dome cylinder and from the dome knuckles of the prolate and the oblate cylinders. Finally, it is recommended that, to comply with DOT CFFC 2007, the dome shape should be designed and fabricated as guided by the isotensoid dome theory.

• Journal of Powder Materials
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• v.14 no.1 s.60
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• pp.13-18
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• 2007

The mother Ni-W (1-5 wt.%) alloy billets for coated conductor substrate were fabricated by powder metallurgy process. The tensile test results for the sintered Ni-W rods showed the increase of mechanical strength and decrease of ductility with increasing W content due to the solid solution hardening. All the fracture surfaces of the tested specimens showed the typical ductile fracture mode of dimple rupture due to the local necking. The Ni-W alloy billets were made into tape by cold rolling. After the appropriate heat treatment for recrystallization, the brass texture formed by the cold rolling was converted to the complete cube texture. The in-plane and out of plane texture of the tapes estimated by x-ray pole figure were smaller than 9 degree and 7 degree, respectively. The effect of the W addition on the texture development seems not to be significant.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.2
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• pp.108-113
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• 2005

The damageability and repairability of similar platform type vehicles could be very concerned with design optimization. In all the vehicles crash tested, small size passenger vehicles were weakness in aspect of damageability and repairability. The most critical area appears to be repair cost considering that parts cost is the largest portion of total repair cost segments. Besides repair cost, attaching method of front sidemember and subframe are placed special importance for impact energy absorption and damageability and repairability. So in order to improve damageability and repairability of vehicle structure and body component of the monocoque type passenger vehicles, the end of front side member and front back beam should be designed with optimum level and to supply the end of front side member as a partial condition approx 300mm. The effectiveness of design concept on the 40% offset frontal impact characteristics of the passenger vehicle structure is investigated and summarized.

• Steel and Composite Structures
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• v.11 no.6
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• pp.469-488
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• 2011

This paper consists of two parts; the first part describes the laboratory work concerning the behavior of lightweight aggregate concrete filled steel tubes (LACFT). Based on eccentricity tests, fifty-four specimens with different slenderness ratios (L/D= 3, 7, and 14) were tested. The main parameters varied in the test are: load eccentricity; steel ratio; and slenderness ratio. The standard load-strain curves of LACFT columns under eccentric loading were summarized and significant parameters affecting LACFT column's bearing capacity, failure mechanism and failure mode such as confinement effect and bond strength were all studied and analyzed through the comparison with predicted strength of concrete filled steel tube columns (CFT) using the existing codes such as AISC-LRFD (1999), CHN DBJ 13-51-2003 (2003) and CHN CECS 28:90 (1990). The second part of this paper presents the results of parametric study and introduces a practical and accurate method for determination of the maximum compressive strength of confined concrete core ($f_{max}$), In addition to, the study of the effect of aspect-ratio and length-width ratio on the yield stress of steel tubes ( $f_{sy}$) under biaxial state of stress in CFT columns and the effect of these two factors on the ultimate load carrying capacity of axially loaded CFT/LACFT columns.

• Journal of Welding and Joining
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• v.33 no.4
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• pp.37-43
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• 2015

Characteristics of dissimilar metal welds between STS 316L and carbon steel ASTM A516 Gr.70 made with GTAW have been evaluated in terms of microstructure, ferrite content, chemical analysis, hardness and corrosion resistance. Three heat inputs of 9.00, 11.25, 13.00kJ/cm were employed to make joints of dissimilar metals with ER309 wire. Based on microstructural examination, the amount of vermicular type of ${\delta}$-ferrite was increased with increasing heat input due to the increase of Creq/Nieq in the second layer of welds. Based on the EDX analysis of weld metals, Cr and Ni content in the 2nd layer increased while those content in the first layer of welds decreased with heat inputs. Cellular solidification mode in the 1st layer and dendritic solidification mode in the 2nd layer due to different cooling rates were prevailed, respectively. Heat affected zone which formed hard microstructure showed higher hardness than the weld metal. The salt spray test of dissimilar metals weld joints showed that the carbon steel surfaces only corroded. The weight loss rate due to corrosion increased up to 100hours but it decreased above 100 hours. There was little difference in the weight loss caused by corrosion regardless of heat inputs.

• Korean Journal of Health Education and Promotion
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• v.11 no.2
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• pp.33-47
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• 1994

AIDS preventional efforts need to be guided by well trained health care personnel especially by school nurses for the adolescents. This study was designed to get basic data about AIDS educational program development for school nurses. The objectives of this study were to 1) identify AIDS knowledg of school nurses 2) identify AIDS attitudes of school nurses and 3) identify association between AIDS knowledge and sociodemographic characteristics. Data were collected from 173 subjects in Chonbuk province. Self-reporting questionnaire were administered during the period from 1st of June to 30th of June, 1994. AIDS related knowledge was measured by using 44 questions on cause(3 items), testing(3 items), mode of transmission(15 items), clinical manifestations(5 items), treatment(3 items), prevention(5 items), complication(4 items), infection control(3 items) and Using resources(3 items). AIDS related attitudes were measured by five point Likert scales using 13 questions on perceived threats from AIDS crisis (4 items), perceived severity to AIDS(2 items), perceived needs about psychosocial care for HIV infected patients(3 items) and perceived educational needs of AIDS(4 items). The collected data were analyzed by SPSS/PC/sup +/, using percentages, Mean and S.D. descriptive purpose and t-test or F for comparing the variables. The major findings were as follows: 1. Respondents ranged in knowledge of AIDS between 0 and 44 with the 33.79 mean score. Percentage of correctly answered respondents to each categories - mode of transmission : 87.0% - clinical manifestation : 85.0% - cause : 82.5% - prevention : 81.5% - treatment : 76.1% - infection control : 72.8% - testing of HIV infection 71.8% - using community resourses : 50.9% - complication : 45.8% 2. The respondents' attitudes of AIDS The majority(70%) showed higher perceived threat The majority(91.3%) showed higher perceived severity to AIDS crisis As a whole, perceived needs about psychosocial care for HIV infected patients negative The majority (over 96.5%) showed highly perceived educational needs of AIDS. 3. The relationship between AIDS knowledge and each of those general character. AIDS knowledge shows significant difference with age(F=3.50, p<.016), years of professional experience(F=4.14, p<.007) and received lecture about AIDS(F=4.54, p<.000). There was no significant difference between AIDS knowledge and job satisfaction.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.9
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• pp.82-90
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• 2014

In this paper, a couple of 4-channel differential transimpedance amplifier arrays are realized in a standard 0.18um CMOS technology for the applications of linear LADAR(laser detection and ranging) systems. Each array targets 1.25-Gb/s operations, where the current-mode chip consists of current-mirror input stage, a single-to-differential amplifier, and an output buffer. The input stage exploits the local feedback current-mirror configuration for low input resistance and low noise characteristics. Measurements demonstrate that each channel achieves $69-dB{\Omega}$ transimpedance gain, 2.2-GHz bandwidth, 21.5-pA/sqrt(Hz) average noise current spectral density (corresponding to the optical sensitivity of -20.5-dBm), and the 4-channel total power dissipation of 147.6-mW from a single 1.8-V supply. The measured eye-diagrams confirms wide and clear eye-openings for 1.25-Gb/s operations. Meanwhile, the voltage-mode chip consists of inverter input stage for low noise characteristics, a single-to-differential amplifier, and an output buffer. Test chips reveal that each channel achieves $73-dB{\Omega}$ transimpedance gain, 1.1-GHz bandwidth, 13.2-pA/sqrt(Hz) average noise current spectral density (corresponding to the optical sensitivity of -22.8-dBm), and the 4-channel total power dissipation of 138.4-mW from a single 1.8-V supply. The measured eye-diagrams confirms wide and clear eye-openings for 1.25-Gb/s operations.

• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.4
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• pp.480-486
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• 2016

Manufacturers have been applying several technologies that can improve the fuel economy of their cars. The regulated voltage control(RVC) system, is one of those technologies being used in passenger cars. In RVC, the voltage of an alternator is controlled depending on the electrical load demand or battery SOC, although each manufacturer differs from another in terms of detail. RVC can reduce the load of an alternator by consuming the stored energy of a battery and simultaneously generate energy. In this paper, a diesel passenger car equipped with an RVC system was tested under FTP-75 and HWFET modes to evaluate fuel economy as their initial battery SOC(100, 90, 80 and 60 %). The test results showed that the initial SOC affects fuel economy only under the FTP-75 mode. FTP-75 fuel economy of the 60% SOC was 13.2 % lower than the 100 % SOC. Also, the simultaneous consumption of the two energy sources did not appear in 60 % SOC.