• KSTLE International Journal
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• 제3권1호
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• pp.26-29
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• 2002

The International Lubricant Standardization and Approval Committee (ILSAC) GF-3 passenger car engine oil specification has been introduced commercially in July 2001. The new specification oil provides superior performance in terms of fuel economy, control of high temperature deposits, and oil consumption. These enhanced performances of GF-3 engine oil need high quality base oil as well as a better additive system. In this paper, the effect of base oil on various performances of ILSAC GF-3 engine oil was investigated. From the GF-3 sequence engine tests, Group III base oil shows better performance in fuel economy retention, oxidation and varnish control than combination of group III and group II or group III and group 1.

• Journal of Welding and Joining
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• 제19권1호
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• pp.82-87
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• 2001

The creep-rupture and low cycle fatigue properties of transient liquid phase bonded joints of Ni-base single crystal superalloy, CMSX-2 was investigated using MBF-80 insert metal. The (100) orientation of bonded specimen was aligned perpendicular to the joint interface. CMSX-2 was bonded at 1523K for 1.8ks in vacuum, optimum bonding condition. The creep rupture strength and rupture lives of the joints were the almost identical to ones of the base metal. SEM observation of the fracture surfaces of joints after creep rupture test revealed that the fracture surfaces classified three types of region, ductile fracture surface, cleavage fracture surface and interfacial fracture surface. The low cycle fatigue properties of the joints were also the same level as those of base metal. The elongation and reduction of area values of joints were comparable to those of base metal while fell down on creep rupture condition of high temperature.

• 한국자기공명학회논문지
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• 제8권2호
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• pp.96-107
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• 2004

We prepared two oligonucleotides containing same base pairing, but different base sequence in the middle region, d(CGAATTCG) and d(CGTATACG). NMR and UV absorbance data represented that such variation in base sequence could cause a significant difference in melting temperature and dynamics between d(CGAATTCG)$_2$ and d(CGTATACG)$_2$ duplexes, which are regarded to be associated with the stacked structure and the width of the minor groove of them. The latter showed poor stability compared to the former, because of poor stacking of bases. And berenil could bind to the minor groove of d(CGAATTCG)$_2$ which is relatively narrow, more strongly than d(CGTATACG)$_2$ and this gave rise to large improvement in thermal stability of the d(CGAATTCG)$_2$ duplex, compared to d(CGTATACG)$_2$.

• 디지털융복합연구
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• 제17권10호
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• pp.223-232
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• 2019

정보통신 산업 발전에 따라 통신장치의 크기는 소형화 되고 발열량이 많이 발생하는 시스템으로 변화하고 있다. 그러므로 무선기지국에는 무선장비의 발열량이 많이 발생하여 에너지가 계속 많이 소모되고 있고 그로 인하여 무선기지국의 장애가 발생 할 우려가 있어 본 연구에서는 효율적이고 효과적인 방법으로 무선기지국내 에너지를 절감하고 기지국운영을 위하여 본 연구를 분석하게 되었다. 연구방법으로는 발열량 및 전기료를 많이 발생하는 기지국 대상으로 실시하였고 기지국 25개를 선정하여 2주간 데이터를 확보 하였다. 신뢰성을 확보하기 위해 실내 온도를 일정하게 $27^{\circ}C$로 유지 하였으며, 제어시스템을 설치하여 2주간 똑 같이 설치하여 date를 분석 확보 하였다. 연구방법에 있어 시험결과를 산출하기 위해 계측기는 전산전력계, 디지털온도계, 분진측정 등이 활용하였다. date분석을 위해 Control Sysetm 설치 전 date와 설치 후 date 분석을 위해 25개 무선기지국대상으로 연구 시험 하였다.

• Restorative Dentistry and Endodontics
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• 제26권5호
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• pp.393-398
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• 2001

Polymerization of light-activated restorations results in temperature increase caused by both the exothermic reaction process and the energy absorbed during irradiation. Within composite resin, temperature increases up to 2$0^{\circ}C$ or more during polymerization. But, insulation of hard tissue of tooth lowers this temperature increase in pulp. However, many clinicians are concerned about intrapulpal temperature injury. The purpose of this study was to evaluate temperature changes in the pulp according to various restorative materials and bases during curing procedure. Caries and restoration-free mandibular molars extracted within three months were prepared Class I cavity of 3$\times$6mm with high speed handpiece fissure bur. 1mm depth of dentin was evaluated with micrometer in mesial and distal pulp horns. Pulp chambers were filled with 37.0$\pm$0.1$^{\circ}C$ water to CEJ. Chromium-alumina thermocouple was placed in pulp horn below restorative materials for evaluating of temperature changes. This thermocouple was connected to temperature-recording device(Multiplication analyzer MX, 6.000, JAPAN). Temperature changes was evaluated from initial 37.$0^{\circ}C$ after temperature changes to 37.$0^{\circ}C$. Tip of curing unit was placed in the center of prepared cavity separated 1mm from restorative materials. Curing time was 40s. The restorative materials were used with Z 100, Fuji II LC, Compoglass flow and bases were used with Vitrebond, Dycal. Resrorative materials were placed in 2mm. The depth of bases were formed in 1mm and in this upper portion, resin of 2mm depth was placed. This procedure was performed 10 times. The results were as follows. 1. All the groups showed that the temperature in pulp increased as curing time increased 2. The temperature increase of glass ionomer was significantly higher than that of Resin and Compomer during curing procedure (P<0.05). 3. The temperature increase in glass ionomer base was significantly higher than that of Calcium hydroxide base during Resin curing procedure (P<0.05).

• Bulletin of the Korean Chemical Society
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• 제35권12호
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• pp.3532-3534
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• 2014

In theoretical simulations of proton transfer in DNA, environmental factors nearly have not been considered. In our calculations, using QM/MM method on the basis of CP2K, proton transfer on adenine-thymine base pair is studied in water, at wide scope temperature, and under the external electric field. Our results indicate that the external electric field induces the proton transfer at room temperature, and its intensity and temperature have some effect on hole localization and proton transfer.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2003년도 가을 학술논문집
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• pp.373-378
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• 2003

$LiCl-Li_2O_2$용융염계에서 용융염 취급장치의 구조재료를 위한 평가의 일환으로 오스테나이트 합금인 Fe-base 및 Ni-base 합금의 부식거동을 분위기온도; 650~$725^{\circ}C$, 부식시간: 24~168h, $Li_2O$농도; 3wt%, 혼합가스농도: Ar-10%$O_2$에서 조사하였다. $LiCl-Li_2O_2$ 용융염계에서 Ni-base 합금이 Fe-base 합금보다 높은 내부식성을 나타내었으며, 또한 Fe-base 합금에서 Fe의 함량이 낮고 Ni의 함량이 높은 경우 부식저항성이 증가하였다. 아울러 Fe-base 합금의 부식생성물은 $Cr_2O_3$, $FeCr_2O_4$ Ni-base 합금에서는 $Cr_2O_3$, $NiFe_2O_4$로 나타났다.

• 한국안전학회지
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• 제28권3호
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• pp.18-22
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• 2013

The Co-base super heat resisting alloy ECY768 is employed in gas turbine because of its high temperature strength and oxidation resistance. The prediction of fatigue life for superalloy is important for improving the efficiency. In this paper, low cycle fatigue tests are performed as variables of total strain range and temperature. The relations between strain energy density and number of cycle to failure are examined in order to predict the low cycle fatigue life of ECY768 super alloy. The lives predicted by strain energy methods are found to coincide with experimental data and results obtained from the Coffin-Manson method. The fatigue lives is evaluated using predicted by Coffin-Manson method and strain energy methods is compared with the measured fatigue lives at different temperatures. The microstructure observing was performed for how affect able to low-cycle fatigue life by increasing the temperature.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2012년도 제38회 춘계학술대회논문집
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• pp.529-531
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• 2012

화포 추진제는 표면을 코팅함으로서 온도 둔감 특성을 얻을 수 있다. 이들 추진제의 연소 속도는 추진제 온도에는 크게 의존 하지 않고, 강내 최대 평균 압력을 이용함으로서 탄 속도 증가에 크게 기여할 수 있다. 본 연구에서는 표면 코팅 추진제의 온도둔감 특성을 Closed Bomb Test(CBT) 및 40미리 고중량탄을 적용한 Simulator Gun 시험을 통하여 확인하였으며, 온도둔감 특성을 가지는 코팅 추진제 제조에 대한 가능성을 확인하였다.

• Journal of Electrochemical Science and Technology
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• 제15권2호
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• pp.220-241
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• 2024

Due to its unique advantages, electrochemical machining (ECM) is playing an increasingly significant role in the manufacture of difficult-to-machine materials. Most of the current ECM research is conducted at room temperature, with studies on ECM in a cryogenic environment not having been reported to date. This study is focused on the electrochemical dissolution characteristics of typical iron and nickel base alloys in NaNO₃ solution at low temperature (-10℃). The polarization behaviors and passive film properties were studied by various electrochemical test methods. The results indicated that a higher voltage is required for decomposition and more pronounced pitting of their structures occurs in the passive zone in a cryogenic environment. A more in-depth study of the composition and structure of the passive films by X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy showed that the passive films of the alloys are modified at low temperature, and their capacitance characteristics are more prominent, which makes corrosion of the alloys more likely to occur uniformly. These modified passive films have a huge impact on the surface morphologies of the alloys, with non-uniform corrosion suppressed and an improvement in their surface finish, indicating that lowering the temperature improves the localization of ECM. Together with the cryogenic impact of electron energy state compression, the accuracy of ECM can be further improved.