• Proceedings of the KSRS Conference
• /
• 2009.03a
• /
• pp.360-366
• /
• 2009

AQUA/AMSR-E 인공위성 자료를 활용하여 3차원 최적내삽 해수면온도 합성장을 생산하였고 시간평균장과 비교하여 문제점과 한계점을 기술하였다. 3-D SST 합성장은 북태평양 중앙부에서 전체적으로 $0.05^{\circ}C$ 이하의 작은 오차를 보였으나, 위성 결측이 있는 연안에서는 $0.4^{\circ}C$ 이상의 비교적 큰 오차를 유발하였다. 강한 강수나 구름으로 인한 결측이 있는 부분에서는 $0.1\sim0.15^{\circ}C$에 달하는 오차를 보였다. 시간평균장과 비교한 결과, 구름 부근의 화소에서는 해수면온도를 낮게 계산하는 경향이 있었으며, 해수면온도의 공간적 구배를 감소시키는 평활화가 전체적으로 나타났다. 저위도에서 OI SST는 실제 해수면온도에는 없는 불연속성을 만드는 경향이 있었고, 이는 OI 과정에서 사용한 윈도우의 크기와 해양 현상의 수평 규모가 위도에 따라 변화하는데서 기인하였다. 현상의 공간 규모의 척도인 로스비 내부 변형 반경은 북태평양에서 O(1) 정도로 위도에 따른 공간적 변화가 큰 것으로 나타났다. 본 연구는 SST 합성장 생산 과정에 위도와 해수의 수직적 밀도 구조와 밀접한 관련이 있는 해양 현상의 수평적 규모의 시공간적 변동 특성을 고려해야 함을 제시한다.

• Plant Journal
• /
• v.13 no.4
• /
• pp.38-40
• /
• 2017

This study is for stabilization of the water balance of the closed cooling water system. The pipe network analysis program is used for the water balance review, and the resistance factor correction is performed through the field measurement with the ultrasonic flowmeter to improve the reliability of the pipe network software. Based on this, it is aimed to derive optimal driving method through various case simulations.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.54 no.7
• /
• pp.339-342
• /
• 2005

We present a new high-frequency equivalent circuit model for 52pin QFP used in typical IC's and extract R, L, and C values of this circuit model using a 3-D E & M field simulator. Futhermore, L and C value variations as a function of Pin number due to the shape differences of the leads have been fitted to 2nd order polynomials in order to extend the applicability of this model.

• Bulletin of the Korean Chemical Society
• /
• v.5 no.2
• /
• pp.55-60
• /
• 1984

The NMR shift arising from the electron angular momentum and electron spin dipolar-nuclear spin angular momentum interactions has been investigated for a $4d^1$system in a strong crystal field environment of tetragonal symmetry. A general formula for NMR shift is used to compute the NMR shifts along the (100), (010), (001), (110) and (111) axes. We find that from the computed results, the NMR shift along the (100) and (010) axes is consistent with each other in a strong crystal field environment of tetragonal symmetry, but the NMR shift along the (001) axis is about triply greater in magnitude than those along the (100) and (010) axes and is opposite in sign to those along (100) and (010) axes. In this work, we express the expansion coefficients $a_1^{(i)}$ and $b_1^{(i)}$ of $A_i$ and $B_i$ in terms of $g_m^{(i)}$ and $h_m^{(i)}$ and two matrices $c_{lm}$ and $d_{lm}$ of radial dependence. The NMR shift is also separated into the contributions of multipolar terms. We find that $1/R^3$ term contributes dominantly to the NMR shift along the (100), (010), (001) and (110) axes while along the (111) axis $1/R^5$ term dominantly contributes. However, the contribtions of the other terms may not be negligible.

• 한국초전도학회:학술대회논문집
• /
• v.10
• /
• pp.257-261
• /
• 2000

The value of I$_c$(critical current) in HTS (High Temperature Superconductor) tape has a great influence on B${\bot}$(vertical field). Therefore, in shape design of field coil for the HTSG(High Temperature Superconducting Generator), a method to reduce the B${\bot}$ should be considered in order to maintain the stability and substantial improvement on the performance. On the basis of the magnetic field analysis, this paper deals with various field coil shape according to the iron plate to obtain small B${\bot}$ by using Biot-Savart's law, image method and 2D FEA(2 Dimensional Finite Element Analysis) considering the stress condition of HTS. Moreover, the analysis is verified by comparison with experimental results. And also this paper presents the advanced model by using 3D FEA, in which flux density at armature is calculated in 5kVA class HTSG.

• Journal of the Korea Institute of Building Construction
• /
• v.19 no.6
• /
• pp.503-510
• /
• 2019

Recently, construction technology of RC structures must be examined for creep in concrete. The factors affecting the creep prediction of concrete and the results of creep in domestic construction field were reviewed. The longer the creep test period and the higher the compressive strength, the higher the creep prediction accuracy. The higher the curing temperature, the higher the initial strength development of the concrete, but the difference in the creep coefficients increased over time. Based on the results of creep evaluation in the domestic construction field and lab. tests, a modified predictive model that complements the ACI-209 model was proposed. In the creep prediction of real members using general to high strength concrete, the test period and temperature should be considered precisely.

• Progress in Superconductivity
• /
• v.3 no.1
• /
• pp.130-133
• /
• 2001

A multifilamentary Bi-2223 HTS tape for superconducting power applications was studied through the fabrication of 250-meter long tapes by the PIT(powder in tube) process. To fabricate continuous long wire, a drawing machine, a two-drum bull block and a rolled tape winding machine were developed. Especially, 250-meter long tapes were heat treated in the shape of pancake coil to reduce the heat affect zone and to achieve the high critical current. Engineering critical current density was improved through both the enhancements of critical current density by control of thermal process and the increase of filling factor by using thin Ag alloy sheath tubes less than 1.5 mm in thickness. We have made successfully 250-meter long 37 filamentary tapes with high filling factor up to 31 % employing the modified drawing and rolling technique. The critical current of 250-meter long tapes with pancake coil type was measured by transport method at self-field up to 250 gauss of center field. The measured values, based on the transport critical current at self-field, $I_{c}$ -B characteristics and magnetic field analysis, are 34 A of I$_{c}$ and 4.0 $kA/\textrm{cm}^2$ of $J_{e}$ at 250 m, 77 K, and 0 T. We also have achieved the 56 A of I$_{c}$ and 7.0 $0 kA/\textrm{cm}^2$ of$ J_{e}$ in short tapes at 77K, self-field, and 1$mutextrm{V}$/cm.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2009.11a
• /
• pp.124-124
• /
• 2009

We observed the changes of crystal structure of Rubrene (5,6,11,12-tetraphenylnaphthacene) polycrystal thin films at various in situ substrate temperature and process by scanning electron microscope(SEM), x-ray diffraction (XRD) and near-field microwave microprobe (NFMM). Amorphous rubrene thin film was initially obtained on 200 nm thick $SiO_2/Si$ substrate at 35 $^{\circ}C$ in a vacuum evaporation but in situ long time postannealing at the temperature 80 $^{\circ}C$ transformed the amorphous phase into crystalline. Four heating conditions are followed : (a) preheating (b) annealing (c) preheating, annealing (d) preheating, cooling(35 $^{\circ}C$), annealing. We have obtained the largest polycrystal disk in sample (c). But the highest crytallity and conductivity of the rubrene thin films were obtained in sample (d).

• Communications of the Korean Mathematical Society
• /
• v.20 no.3
• /
• pp.437-442
• /
• 2005

In studying injective covers, the modules C such that Hom(E, C) = 0 and $Ext^1$(E, C) = 0 for all injective module E play an important role because of Wakamatsu's lemma. If C is a module over the ring k[[x, y]] with k a field, the class of these modules C contains the class $\={D}$ of all direct summands of products of modules of finite length ([3, Theorem 2.9]). In this paper we show that every module over any commutative ring has a $\={D}$-preenvelope.

• Proceedings of the KIEE Conference
• /
• 1996.07c
• /
• pp.1633-1635
• /
• 1996

This phenomena of streaming-electrification is generated between solid and liquid boundary called electric double-layer which is generated by potential difference. A charge separation at interfaces between a moving fluid and a solid boundary can give rise to the generation of substantial electric field and at last these can give rise ta insulating failure. Therefore injection of the adverse-charge in streaming-electrified insulating oil to eliminate the accumulation charge and its related phenomena was investigated.