• Nuclear Engineering and Technology
• /
• 제55권12호
• /
• pp.4518-4526
• /
• 2023

NECP-SARAX is a neutronics analysis code system for advanced reactor developed by Nuclear Engineering Computational Physics Laboratory of Xi'an Jiaotong University. In past few years, improvements have been implemented in TULIP code which is the cross-section generation module of NECP-SARAX, including the treatment of resonance interface, considering the self-shielding effect in non-resonance energy range, hyperfine group method and nuclear library with thermal scattering law. Previous studies show that NECP-SARAX has high performance in both fast and thermal spectrum system analysis. The accuracy of TULIP code in fast and thermal spectrum system analysis is demonstrated preliminarily. However, a systematic verification and validation is still necessary. In order to validate the applicability of TULIP code for full energy range, 147 fast spectrum critical experiment benchmarks and 170 thermal spectrum critical experiment benchmarks were selected from ICSBEP and used for analysis. The keff bias between TULIP code and reference value is less than 300 pcm for all fast spectrum benchmarks. And that bias keeps within 200 pcm for thermal spectrum benchmarks with neutron-moderating materials such as polyethylene, beryllium oxide, etc. The numerical results indicate that TULIP code has good performance for the analysis of fast and thermal spectrum system.

• 한국전기화학회:학술대회논문집
• /
• 한국전기화학회 2001년도 전지기술심포지움
• /
• pp.145-161
• /
• 2001

Novel characterization of thermal properties of a battery has been introduced by defining its frequency-dependent thermal impedance function. Thermal impedance function can be approximated as a thermal impedance spectrum by analyzing experimental temperature transient which is related to the thermal impedance function through Laplace transformation. In order to obtain temperature transient, a process has been devised to generate external heat pulse with heating wire and to measure the response of battery. This process is used to study several commercial Li-ion batteries of cylindrical type. The thermal impedance measurements have been performed using potentionstat/galvanostate controlled digital signal processor, which is more commonly available than flow-meter usually applied for thermal property measurements. Thermal impedance spectra obtained for batteries produced by different manufactures are found to differ considerably. Comparison of spectra at different states of charge indicates independence of thermal impedance on charging state of battery. It is shown that thermal impedance spectrum can be used to obtain simultaneously thermal capacity and thermal conductivity of battery by non-linear complex least-square fit of the spectrum to thermal impedance model. Obtained data is used to simulate a response of the battery to internal heating during discharge. It is found that temperature inside the battery is by one-third larger that on its surface. This observation has to be considered to prevent damage by overheating.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2011년도 제40회 동계학술대회 초록집
• /
• pp.14-14
• /
• 2011

Graphene is known to possess excellent thermal properties, including high thermal conductivity, that make it a prime candidate material for heat management in ultra large scale integrated circuits. For device applications, the key parameters are the thermal expansion coefficient and the thermal conductivity. There has been no reliable experimental determination on the thermal expansion coefficient of graphene whereas the estimates of the thermal conductivity vary widely. In this work, we estimate the thermal expansion coefficient of graphene on silicon dioxide by measuring the temperature dependence of the Raman spectrum. The shift of the Raman peaks due to heating or cooling results from both the intrinsic temperature dependence of the Raman spectrum of graphene and the strain on the graphene film due to the thermal expansion mismatch with silicon dioxide. By carefully comparing the experimental data against theoretical calculations, it is possible to determine the thermal expansion coefficient. The thermal conductivity is measured by estimating the thermal profile of a graphene film suspended over a circular hole of the substrate.

• 천문학회보
• /
• 제42권2호
• /
• pp.78.4-79
• /
• 2017

Thermal inflation is an additional inflationary mechanism before the big bang nucleosynthesis, which solves the moduli problem and naturally provides a plausible dark matter candidate. Thermal inflation leaves a slight enhancement followed by huge suppression of a factor of ~50 in the curvature and matter power spectrum, which can be expressed in terms of a single characteristic scale $k_b$. Here we describe the observability of the small-scale features of thermal inflation from various observations, such as CMB distortion, satellite galaxy abundance in the Milky-Way-sized galaxies, and 21-cm power spectrum before the epoch of reionization.

• 한국자기학회지
• /
• 제21권1호
• /
• pp.5-9
• /
• 2011

M형 Ba-ferrite 결정에서 5가지 자리에 위치한 Fe 이온의 열 진동에 관하여 M$\ddot{o}$ssbauer 분광법과 Raman 분석으로 연구하였다. 결정의 c-축 방향을 기준으로 감마선을 여러 방향으로 조사하여 각 방향에 대한 열진동의 형태를 측정 분석하였다. 특히 2b 자리에서 c-축 방향의 진동은 다른 방향 보다 매우 활발하여 M$\ddot{o}$ssbauer 공명 흡수에 큰 변화를 일으키고 있으며 Raman 측정에서도 2b 자리의 진동이 매우 크게 나타나는 특이한 성질을 나타내고 있다.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2017년도 추계 학술논문 발표대회
• /
• pp.37-38
• /
• 2017

In Infrared rays, which are 50% of sunlight, act as heat rays to heat buildings. Solar heat paint is widely used to protect buildings from sunlight. Solar heat coatings are used to block buildings form sunlight. Solar heat paints are classified as heat-reflective paints and heat-insulating paints according to the differential thermal mechanism. In this study, we study the thermal differential mechanism by analyzing the temperature change of the coated steel plate and the solar reflection spectrum on the surface. In this experiment, exposed steel plate, heat-reflective coated steel plate, heat-insulating coated steel plate, and general paint coated steel plate were used. As a result, when the infrared rays of 780nm ~ 1400nm were irradiated, the heat reflective paint had a temperature lower by 10 degrees than other paints. Analysis of the reflection spectrum of the paint shows that the heat paint is lower in heat than other paints because it has higher reflectance of light and absorbs much of the infrared rays.

• Nuclear Engineering and Technology
• /
• 제5권4호
• /
• pp.291-309
• /
• 1973

TRIGA Mark II와 III 원자로의 여러가지 가동조건에 있어서 노벽으로 부터의 누설 ${\gamma}$선에 의한 조사선양률을 3"$\times$3"원통형 NaI(T1) 섬광계수기와 400 channel파 고분석장치로 측정하였는데 측정된 spectrum으로부터 조사선양률을 산출하는데는 실제적면에서 복잡하기 짝이 없는 response matrix 방법대신 정도가 좋으면서도 비교적 그 과정이 단순한 Moriuchi의 specturm -조사선양률 환산 이론을 적용하였다. 연구결과에 따르면 노심에서 발생된 누설 ${\gamma}$선의 기본적인 spectrum 형태는 원자로의 열출력이나 차장벽에 의한 강도의 감쇠에 별로 영향을 받지 않고 있으며 원자로 누설${\gamma}$선에 의란 전조사선양률의 공기중에서의 감쇠는 폭 넓은 energy분포에도 불구하고 지수함수적 감쇠를 하고 있음이 판명되있다. 이 전조사선양률은 원자로의 열출력에 대체로 비례하고 있으나 TRIGA Mark III과 같은 가동형노심의 경우는 측정된 spectrum이 매우 다양한바, 그로부터 산출된 전조사선양률의 크기에는 관계없이, spectrum 분해방법을 적용하여 노심에서 발생된 누설 ${\gamma}$선과 원자로가동중 발생되는 여지 ${\gamma}$선의 기여를 판별 해석하는데 성공하였다.

• 한국전기전자재료학회논문지
• /
• 제26권4호
• /
• pp.294-297
• /
• 2013

ZnO crystals with octahedral shape were synthesized by thermal evaporation technique. $ZnF_2$ powder was used as the source material. The thermal evaporation and oxidation of $ZnF_2$ powder was carried out for 1 hr at $1,000^{\circ}C$ in air under atmospheric pressure. SEM images showed that the ZnO crystals produced by oxidizing $ZnF_2$ vapor possessed a characteristic octahedral shape. XRD spectrum revealed that the ZnO octahedron had hexagonal wurtzite structure. In the room temperature photoluminescence spectrum, a strong green emission peak at around 510 nm was observed.

• 한국음향학회지
• /
• 제12권1호
• /
• pp.47-54
• /
• 1993

Performance analysis is very important to transmit the high quality information and to construct the optimal system for the minimze the noise from the channel of spread spectrum system. In this paper the error rate performance is analyzed with computer simulation in noncoherent frequency hopping M-qry frequency shift keying(FH/MFSk) systems with regard to thermal noise under the partial band jamming environments. AS a result, in case the thermal noise is disregarded, bit error probability of system in jamming fraction ρ and Eb/Nj(bit energy to jamming power density) is reduced with the increase of K and in worst case 32FSK system is better than 2FSK system by 3.23dB with the variatio of Eb/Nj. In case thermal noise is considered, bit error probability of system by 3.23dB with the variation of Eb/Nj. In case thermal noise is considered, bit error probability of system are reduced with the increase of K and Eb/No(bit energy to thermal noise density). Bit error probability in connection with worst case ρ is not largely influenced form over the 14dB to K=1 and 8dB to K=5 accordingly thermal noise disregarding. These results may be useful for avoiding the common vulnerabilities when the spread spectrum system is designed.

• Nuclear Engineering and Technology
• /
• 제40권2호
• /
• pp.117-126
• /
• 2008

In this paper, a new reactor core design is proposed on the basis of a mixed core concept consisting of a thermal zone and a fast zone. The geometric structure of the fuel assembly of the thermal zone is similar to that of a conventional thermal supercritical water-cooled reactor(SCWR) core with two fuel pin rows between the moderator channels. In spite of the counter-current flow mode, the co-current flow mode is used to simplify the design of the reactor core and the fuel assembly. The water temperature at the exit of the thermal zone is much lower than the water temperature at the outlet of the pressure vessel. This lower temperature reduces the maximum cladding temperature of the thermal zone. Furthermore, due to the high velocity of the fast zone, a wider lattice can be used in the fuel assembly and the nonuniformity of the local heat transfer can be minimized. This mixed core, which combines the merits of some existing thermal SCWR cores and fast SCWR cores, is proposed for further detailed analysis.