• Journal of Korea Foundry Society
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• v.22 no.2
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• pp.69-74
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• 2002

The effects of heat treatments and alloying elements on the microstructure and mechanical charaterisitics of specially austempered ADIs containing alloying elements such as Cu, Mo and Ni were investigated. To compare with the effect of conventional and normal(CN) austempering treatment, two kinds of special austempering treatments which are those with pre-quenching and pre-heating were conducted. The hardness and uniaxial fatigue tests were carried out to evaluate the mechanical charateristics. The hardness of ADI treated by CN heat cycles was higher than those of other ADIs. Cu added ADI (Cu-ADI) tempered at 400 after austenitizing exhibited the highest fatigue life cycles. While austempering after prequenching makes the austenite with high carbon stable, which resulted in transformation to highly strengthened bainites from the carbon enriched austenite phases during tempering. The high carbon enriched banites is considered to improve the fatigue strength.

• Journal of the Korean Society for Heat Treatment
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• v.11 no.2
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• pp.121-130
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• 1998

The effects of alloying elements(Mo, Cu, Ni) and austempering temperature conditions on the microstructural morphologies and mechanical properties in austempered ductile cast iron has been investigated. The austempering at $350^{\circ}C$ for 2hrs after austenitizing at $900^{\circ}C$ for 2hrs in all specimens with various alloying elements was optimum because the good combination of tensile and yield strength, hardness and impact value was obtained. The microstructures of these ADIs treated by a forementioned austempering condition are nearly a mixture type of needle and feathery bainite. Among those alloys, Mo-Cu alloyed DCI had the best optimum mechanical properties of hardness and toughness for automobile parts by austempering treatment for 2hrs at $900^{\circ}C$ followed by $350^{\circ}C$ for 2hrs.

• International Journal of Ocean System Engineering
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• v.2 no.4
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• pp.223-232
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• 2012

For the accurate estimation of the position and orientation of a UUV (unmanned underwater vehicle), a low-cost AHRS (attitude heading reference system) was developed using a low-cost IMU (inertial measurement unit) sensor which provides information on the 3D acceleration, 3D turning rate and 3D earth-magnetic field data in the object coordinate system. The main hardware system is composed of an IMU sensor (ADIS16405) and TMS320F28335, which is coded with an extended kalman filter algorithm with a 50-Hz sampling frequency. Through an experimental gimbal device, good estimation performance for the pitch, roll, and yaw angles of the developed AHRS was verified by comparing to those of a commercial AHRS called the MTi system. The experimental results are here presented and analyzed.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.153-160
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• 2001

피에조콘관입시험(PCPT)의 소산시험은 in-situ 상태의 압밀계수(c/sub v/)를 추정하는 방법으로 널리 이용되어왔다. 본 연구에서는 spherical cavity expansion theory 및 axisymmetric uncoupled linear consolidation equation(Gupta & Davidson, 1986)을 이용하여 과압밀점토에서의 초기과잉간극수압의 분포 및 과잉간극수압의 시간에 대한 소산현상을 해석하는 수치해석방법을 제안하여 현장시험결과 및 실내시험결과와 비교 분석하였다. ADIS (alternating direction implicit scheme)를 이용한 FDM 해석을 실시한 결과와 현장시험의 소산곡선은 잘 부합되는 것으로 나타났으며 압밀계수도 실내실험 또는 피에조콘관입 시험에 대한 추정방법으로 산출된 값과 비교적 일치하는 것으로 나타났다.

• RED RIBBON
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• s.63
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• pp.10-13
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• 2005

증가하는 HIV/AIDS 감염과 그로 인한 파괴적 결과는 세계적 관심사가 되었고, 발병률이 높은 지역에서 AIDS는 보건의료 문제를 넘어서 국민총생산을 감소시키는 사회경제적 문제가 되고 있다. 한국은 상대적으로 HIV감염 AIDS 발병률이 낮은 나라지만 당초 예상과는 달리 그 발병률이 둔화되고 있지 않으며, 1999년 이후 최근에는 감염자의 수가 급격히 증가하는 추세에 있다. 세계 다른 나라들이나 아시아의 주변국의 사정을 보면 우리나라도 결코 안전한 권역에 계속 머물러 있으리라는 장담을 하기가 어렵다. 특히 근년에 경제적 생산력이 왕성한 $20\~30$대 남성에서 HIV/ADIS 증가하고 있어, HIV/AIDS감염의 사회적 비용, 그 중에 특히 경제적 영향에 대한 관심이 커지고 있는 상황이다. 따라서 우리나라에서 발생하는 HIV/AIDS의 경제적 비용을 추산함으로써 증가하는 HIV/AIDS감염의 경제적 의미를 찾을 필요가 있다고 판단된다. 경제적 비용의 추산에 앞서 우선 우리나라 HIV/AIDS 감염자 수를 추계하여 보면 다음과 같다.

• Korean Journal of Microbiology
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• v.29 no.1
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• pp.1-7
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• 1991

Human immunodeficiency virus type 1 (HIV-1) causes a deadly infectious disease, Acquired Immunodeficiency Syndrome (ADIS). As a first step to develop a reliable and fast diagnostic procedure for HIV-1 infection, we cloned various immunodominant epitopes of HIV-1 in bacterial expression vectors containing tac or trp promoter. While the protein level of direct expression of gp160 was low, trp E fused gp120, gp41 and p17-p24 were produced at high levels (15-30% of total bacterial proteins) in E. coli. Since gp120 and gp41 contain relatively conserved regions which can react with antibodies in the plasma from most of HIV-1 infected individuals, these expression clones were used for large preparations of HIV-1 antigens.

• International Journal of Ocean System Engineering
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• v.1 no.3
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• pp.165-170
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• 2011

In this paper, for the accurate estimation of the position and orientation of the UUV (unmanned underwater vehicle), an AHRS (Attitude Heading Reference System) was developed using the IMU (inertial measurement unit) sensor which provides information on acceleration and orientation in the object coordinate and the initial alignment algorithm and the E-KF (extended Kalman Filter). The initial position and orientation of the UUV are estimated using the initial alignment algorithm with 3-axis acceleration and geomagnetic information of the IMU sensor. The position and orientation of the UUV are estimated using the AHRS composed of 3-axis acceleration, velocity, and geomagnetic information and the E-KF. For the performance test of the orientation estimation of the AHRS, a testbed using IMU sensor(ADIS16405) and DSP28335 coded with an E-KF algorithm was developed and its performance was verified through tests.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.1
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• pp.7-15
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• 2012

The levels of indicator PCBs were determined in 132 human milk samples (Colostrum, 30th days after delivery, 60th days after delivery) collected in 2006 according to World Health Organization's (WHO) protocol. In addition, concentrations of indicator polychlorinated biphenyls (PCBs) were measured by the isotope dilution method with high resolution gas chromatograph/high resolution mass detector (HRGC/HRMS), which gave accurate and precise data for estimations of international trend and comparisons. Average daily intakes (ADIs) of all analytes were calculated. The median level of total indicator PCBs was 14 ng/g lipid, which is significantly lower than the level found in individuals from other countries. PCB congeners 138, 153 and 180 accounted for about 65% of the sum of the indicator congeners analyzed. The concentration of the most abundant PCB 153 is positively correlated with the concentration of the sum indicator PCBs (p<0.001). In this study, concentrations of total indicator PCBs significantly decreased with increasing number of children for a mother, indicating that parity and breast-feeding period an important role in the accumulation and elimination of these compounds in lactating women. The ADI for the median of total indicator PCBs for an infant was evaluated at $0.077{\mu}g/kg{\cdot}bw/day$ from birth to 6 months of age. The present study shows that concentrations of PCB 118 primipara breast milk have decreased 25~35 since 1998, and that this trend is continuing.

• Advances in aircraft and spacecraft science
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• v.5 no.4
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• pp.411-430
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• 2018

This computational study examines the augmentation of classic 2-D Rayleigh-$B{\acute{e}}nard$ convection by the addition of periodically-spaced transverse fins. The fins are attached to the heated base of the cavity and serve to partition the cavity into 'units' with different aspect ratios. The respective impacts upon heat transfer of the fin configuration parameters - including spacing, height, thickness and thermal conductivity - are systematically examined through numerical simulations for a range of laminar Rayleigh numbers (0 < Ra < $2{\times}10^5$) and reported in terms of an average Nusselt number. The selection of the low Rayleigh number regime is linked to likely scenarios within aerospace applications (e.g. avionics cooling) where the cavity length scale and/or gravitational acceleration is small. The net heat transfer augmentation is found to result from a combination of competing fin effects, most of which are hydrodynamic in nature. Heat transfer enhancement of up to $1.2{\times}$ that for a Rayleigh-$B{\acute{e}}nard$ cavity without fins was found to occur under favorable fin configurations. Such configurations are generally characterized by short, thin fins with half-spacings somewhat less than the convection cell diameter from classic Rayleigh-$B{\acute{e}}nard$ theory. In contrast, for unfavorable configurations, it is found that the introduction of fins can result in a significant reduction in the heat transfer performance.

• The Journal of Korean Physical Therapy
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• v.15 no.4
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• pp.235-254
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• 2003

The purpose of this descriptive study was to investigate the general knowledge and attitude of physical therapist to patient with HIV/AIDS. Many physical therapists are afraid of AIDS patients because they have a little information of AIDS and fear of HIV infection from AIDS patients at work site. This study was carried out from June to October in 2003 for collecting data. The 271 physical therapists volunteered for a this study and completed questionnaires. The findings of this study can be summarized as follows. 1)The knowledge of prevention of HIV/AIDS influences the attitude of physical therapists to patients with HIV/AIDS. 2)The knowledge of symptoms of HIV/AIDS influences the attitude of physical therapists to patients with HIV/AIDS. 3)The knowledge of transmission routes of HIV/AIDS influences the attitude of physical therapists to patients with HIV/AIDS. 4)84.9 percentage of participant in survey suggested college should have curriculum about HIV/AIDS. In conclusion, physical therapists with more knowledge of HIV/ADIS could positively treat HIV/AIDS patients.