• 제목/요약/키워드: Counterpart test

검색결과 94건 처리시간 0.025초

전차선용 Cu-$TiB_2$ 복합재료의 마모거동에 관한 분석 (The Analysis on Wear Behavior of Cu-$TiB_2$ Composite For Contact Wire)

  • 김정남;이태우;권성태;강계명
    • 한국철도학회:학술대회논문집
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    • 한국철도학회 2004년도 추계학술대회 논문집
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    • pp.704-709
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    • 2004
  • The wear behavior and the mechanical property of Cu-$TiB_2$ composites were examined. Cu-$TiB_2$ composites were fabricated by hot extrusion and cold drawing with $TiB_2$ contents(1$\∼$5vol.$\%$) and the size of $TiB_2$ particles(10$\mu$m and 20$\mu$m). The pin-an-disk wear test was carried out under dry sliding wear conditions which loads varied with from 20N to 100N. At the time, counterpart wear material used SM45C. The experimental results showed that the friction coefficient and wear rate decreased with increasing the $TiB_2$ contents and decreasing the size of $TiB_2$ particle. Also, the depth of plastically deformed zone decreased with increasing the $TiB_2$ contents and decreasing the size of $TiB_2$ particle.

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제곱근 회로를 이용한 온도와 공급 전압에 둔감한 CMOS 정전류원 (A temperature and supply insensitive CMOS current reference using a square root circuit)

  • 이철희;손영수;박홍준
    • 전자공학회논문지C
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    • 제34C권12호
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    • pp.37-42
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    • 1997
  • A new temperature and supply-insensitive CMOS current reference circuit was designed and tested. Te temperature insensuitivity was achieved by eliminating the mobility dependence term through the multiplication of two current components, one which is proportional to mobility and the other which is inversely proportional to mobility, by using a newly designed CMOS square root circuit. The CMOS sqare root circuit was derived from its bipolar counterpart by operating the MOS transistors in the subthreshold region. The supply insensitivity was achieved by using an internal voltage generator. Te test chip was designed ans sent out for fabrication by using a 2.mu.m double-poly double-metal n-well CMOS technology. When an external voltage source was used for the square root circuit, the maximum variation and the average temperature sensitivity were measured to be 3% and 21.4ppm/.deg.C, respectively, for the temperature range of -15~130.deg.C. The maximum current variation with supply voltage was measured to be 3% within the commerical supply voltage range of 4.5~5.5V at 30.deg. C.

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구름 마모시험 장비(Rolling wear tester)를 이용한 마모 후의 접촉각과 자가세정 효과와의 관계 규명을 통한 재료 내구성 평가 (Evaluation of Material Durability by Identifying the Relationship between Contact Angle after Wear and Self-cleaning Effect Using Rolling Wear Tester)

  • 박경렬;최용석;강성민;김운성;정경은;박영진;이경준
    • Tribology and Lubricants
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    • 제39권6호
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    • pp.256-261
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    • 2023
  • This study is conducted to evaluate the durability of superhydrophobic surfaces, with a focus on two aspects: contact angle measurement and self-cleaning-performance analysis. Superhydrophobic copper and aluminum surfaces are fabricated using the immersion method and subjected to a rolling wear test, in which a 2 kg weight is placed on a rolling tester, under loaded conditions. To evaluate their durability, the contact angles of the specimens are measured for each cycle. In addition, the surface deformation of the specimens before and after the test is analyzed through SEM imaging and EDS mapping. The degradation of the self-cleaning performance is evaluated before and after the wear test. The results show that superhydrophobic aluminum is approximately 4.5 times more durable than superhydrophobic copper; the copper and aluminum specimens could endure 21,000 and 4,300 cycles of wear, respectively. The results of the self-cleaning test demonstrate that superhydrophobic aluminum is superior to superhydrophobic copper. After the wear test, the self-cleaning rates of the copper and aluminum specimens decrease to 72.7% and 83.4%, respectively. The relatively minor decrease in the self-cleaning rate of the aluminum specimen, despite the large number of wear cycles, confirms that the superhydrophobic aluminum specimen is more durable than its copper counterpart. This study is expected to aid in evaluating the durability of superhydrophobic surfaces in the future owing to the advantage of performing wear tests on superhydrophobic surfaces without damaging the surface coating.

모자보건수첩보유, 디피티 추가 예방접종에 대한 인지와 디피티 추가 예방접종 실천간의 관계연구 (The Relationship between Retention of the Maternal Child Health Handbook, Awareness of DPT Additional Immunization and DPT Additional Immunization)

  • 정인숙
    • 지역사회간호학회지
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    • 제15권1호
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    • pp.76-83
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    • 2004
  • Purpose: This study was aimed at investigating the relationship between retention of the maternal child health handbook, awareness of DPT additional immunization and DPT additional immunization, and to provide basic information to enhance the DPT additional immunization rate. Method: The study subjects were 312 women whose children were between four and six years old, and residing in six provinces of Gyungsangnam do. Data was collected with a 10 item questionnaire by interviews from July 1st to 30th, 2003, and analyzed with descriptive statistics and X2 test at a significance level of 0.05, by two tailed test. Results: The awareness of DPT additional immunization was significantly higher in the women who retained the maternal child health handbook, than their counterparts. The rate of DPT additional immunization was significantly higher in the women who were aware of the DPT additional immunization or who retained the maternal child health handbook, than their counterpart. Conclusion: The DPT additional immunization rate was related to retention of the maternal child health handbook and awareness of DPT additional immunization. Therefore it is recommended that measures be developed and taken to increase the retention rate of the maternal child health handbook and awareness of DPT additional immunization, to enhance the rate of DPT additional immunization.

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해충저항성 Bt벼의 환경위해성 평가 : 해충저항성 Bt벼가 미꾸리(Misgurnus anguillicaudatus) 및 잉어(Cyprinus carpio)에 미치는 영향 (Risk Assessment and Evaluation of Bt-transgenic Rice : Responses of Misgurnus anguillicaudatus and Cyprinus carpio fed on Bt-transgenic Rice Variety)

  • 오성덕;이대용;손수인;이기종;류태훈;이장용;박범석;권순종;서석철;박종석
    • 한국국제농업개발학회지
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    • 제23권5호
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    • pp.570-577
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    • 2011
  • 해충저항성 Bt벼와 낙동벼의 미꾸리(Misgurnus anguillicaudatus)와 잉어(Cyprinus carpio)에 대한 급성독성시험을 실시한 결과 48시간 및 96시간-LC50은 1,000mg/L 이상으로 나타났다. 48시간 및 96시간 무영향농도(NOEC)는 1,000mg/L이었다. 급성독성 시험기간 중 해충저항성 Bt벼와 낙동벼간의 pH, DO, 수온, 체중 및 전장에 대한 유의적인 결과는 나타나지 않았다.

KRUGLYAK과 LANDER의 유전연관성 비모수 방법과 반복 자료를 고려한 가중 회귀분석법의 비교 (Comparisons of Kruglyak and Lander's Nonparametric Linkage Test and Weighted Regression Incorporating Replications)

  • 최은경;송혜향
    • 응용통계연구
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    • 제21권1호
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    • pp.1-17
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    • 2008
  • 형제 쌍(sibpair)의 연속형 형질(continuous traits) 자료를 이용한 유전연관성 검정 법(linkage test)으로서 Haseman과 Elston (1972)의 최소제곱(ordinary least square, OLS) 회귀분석법이 주로 사용된다. 비모수적 방법으로서 제시된 Kruglyak과 Lander (1995)의 검정통계량은 Haseman과 Elston (1972)의 방법에 대응되는 방법처럼 보이지만 실제로는 매우 다르다. 본 논문에서는 Kruglyak와 Lander (1995)의 검정통계량과 Haseman과 Elston (1972)의 검정통계량의 관계를 설명하고 모의실험으로 두 검정통계량의 검정력을 비교한다. 유전연관성에 사용되는 형제 자료의 특징은 한정된 설명변수의 값에 매우 많은 자료가 반복(replicated)되었다는 점이며, 이러한 반복 자료에 더욱 적절한 가중 회귀분석법을 제안한다. 가중 회귀분석법의 효율성을 정규분포 또는 정규분포가 아닌 연속형 형질 모의실험 자료로 알아본 결과 형제 쌍 자료의 유전연관성 검정에서 가중 회귀분석법이 다른 검정법들보다도 검정력이 높음을 확인하였다.

The Characteristics of Risk Factors in Korean CAD Patients Comparing to American Counterpart and Its Implications to Prevention of CAD

  • Kim, Wan-Soo
    • 대한물리의학회지
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    • 제12권2호
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    • pp.9-20
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    • 2017
  • PURPOSE: The purpose of this study is to understand the difference in the risk factors of coronary artery disease (CAD) between Korean and American CAD patients to determine the discriminant factor for each group, as well as to provide useful information to be reflected in the national concern of health. METHODS: Data were collected from 248 Korean and 107 American CAD patients who underwent either percutaneous coronary intervention or coronary artery bypass grafting. By using t-test and $X^2$-test, risk factors were compared between the Koreans and Americans. To elucidate which risk factor was the most discriminant for each group, logistic regression analysis was performed. RESULTS: All risk factors, except diastolic blood pressure, showed a significant difference between the two groups. $X^2$-test showed statistical significance with respect to the smoking rate between the female groups. Moreover, there was a statistically significant difference between the two groups regarding blood total cholesterol (TC) and triglyceride, and between the male groups, here was a statistically significant difference with respect to blood high-density lipoprotein cholesterol (HDL). Diabetes mellitus (DM) was the most discriminant factor for Korean patients while TC/HDL is the most discriminant for the Americans. CONCLUSION: The characteristics of CAD risk factors were determined to be different between Koreans and Americans in this study. TC/HDL was a discriminant factor for Americans while DM was a discriminant factor for Koreans. This result implies that DM should primarily be given attention to prevent CAD in Korean adults.

핵 연료봉 표면보호를 위한 수용성 건식 윤활제 개발 (Development of a Water-soluble Dry Lubricant for Nuclear Fuel Rod Protection)

  • 정근우;김영운;이상봉;홍종승;한상재;오명호
    • Tribology and Lubricants
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    • 제30권6호
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    • pp.343-349
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    • 2014
  • Currently, in order to resist the scratching of the fuel rod surface while fabricating the fuel assembly of the light-water nuclear reactor, we use a solution of nitrocellulose, an explosive material, as a dry lubricant along with its solvent. However, the demand for developing safe and harmless aqueous alternative materials for environment-conservation and field-worker safety has increased. In this study, we demonstrate the preparation of a novel aqueous resin composite using a formulation of aqueous polymeric resin, alcoholic solvent, and water. Subsequently, we characterize this composite on the basis of hardness, adhesive property, and water solubility using plates similar to the fuel rod material. The insertion test of a fuel rod coated with the YS-3 composite shows load values of $18.8-20.5kg/cm^2$, which is comparable with $18.8-20.5kg/cm^2$ of the nitrocellulose coating agent. In addition, the depth and width of longitudinal scratches caused by the YS-3 composite test are 50% higher than those of the standard. We can develop a harmless and safe aqueous dry lubricant to replace the existing NC products through field testing of 264 pieces of fuel rods, after producing 350 kg of the YS-3 prototype. The scratch test for the rod surface showed that weight of chip of YS-3 prototype was smaller than that of NC before and after solvent treatment, indicating the properties of YS-3 prototype was comparable to the counterpart.

Large-scale cyclic test on frame-supported-transfer-slab reinforced concrete structure retrofitted by sector lead rubber dampers

  • Xin Xu;Yun Zhou;Zhang Yan Chen;Da yang Wang;Ke Jiang;Song Wang
    • Earthquakes and Structures
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    • 제26권5호
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    • pp.383-400
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    • 2024
  • For a conventionally repaired frame-supported-transfer-slab (FSTS) reinforced concrete (RC) structure, both the transfer slab and the beam-to-column and transfer slab-to-column joints remain vulnerable to secondary earthquakes. Aimed at improving the seismic performance of a damaged FSTS RC structure, an innovative retrofitting scheme is proposed, which adopts the sector lead rubber dampers (SLRDs) at joints after the damaged FSTS RC structure is repaired by conventional approaches. In this paper, a series of quasi-static cyclic tests was conducted on a large-scale retrofitted FSTS RC structure. The seismic performance was evaluated and the key test results, including deformation characteristics, damage pattern, hysteretic behaviour, bearing capacity and strains on key components, were reported in detail. The test results indicated that the SLRDs started to dissipate energy under the service level earthquake, and thus prevented damages on the beam-to-column and transfer slab-to-column joints during the secondary earthquakes and shifted the plastic hinges away from the beam ends. The retrofitting scheme of using SLRDs also achieved the seismic design concept of 'strong joint, weak component'. The FSTS RC structure retrofitted by the SLRDs could recover more than 85% bearing capacity of its undamaged counterpart. The hysteresis curves were featured by the inverse "S" shape, indicating good bearing capacity and hysteresis performance. The deformation capacity of the damaged FSTS RC structure retrofitted by the SLRDs met the corresponding codified requirements for the case of the maximum considered earthquake, as set out in the Chinese seismic design code. The stability of the FSTS RC structure retrofitted by the SLRDs, which was revealed by the developed stains of the RC frame and transfer slab, was improved compared with the undamaged FSTS RC structure.

Maximum concrete stress developed in unconfined flexural RC members

  • Ho, J.C.M.;Pam, H.J.;Peng, J.;Wong, Y.L.
    • Computers and Concrete
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    • 제8권2호
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    • pp.207-227
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    • 2011
  • In flexural strength design of unconfined reinforced concrete (RC) members, the concrete compressive stress-strain curve is scaled down from the uni-axial stress-strain curve such that the maximum concrete stress adopted in design is less than the uni-axial strength to account for the strain gradient effect. It has been found that the use of this smaller maximum concrete stress will underestimate the flexural strength of unconfined RC members although the safety factors for materials are taken as unity. Herein, in order to investigate the effect of strain gradient on the maximum concrete stress that can be developed in unconfined flexural RC members, several pairs of plain concrete (PC) and RC inverted T-shaped specimens were fabricated and tested under concentric and eccentric loads. From the test results, the maximum concrete stress developed in the eccentric specimens under strain gradient is determined by the modified concrete stress-strain curve obtained from the counterpart concentric specimens based on axial load and moment equilibriums. Based on that, a pair of equivalent rectangular concrete stress block parameters for the purpose of flexural strength design of unconfined RC members is determined.