• Nuclear Engineering and Technology
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• v.44 no.7
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• pp.709-718
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• 2012

The pressurized water reactor APR1400 adopts DVI (Direct Vessel Injection) for the emergency cooling water in the upper downcomer annulus. The International Standard Problem number 50 (ISP-50) was launched with the aim to investigate thermal hydraulic phenomena during a 50% DVI line break scenario with best estimate codes making use of the experimental data available from the ATLAS facility located at KAERI. The present work describes the calculation results obtained for the ISP-50 using the RELAP5/MOD3.3 system code. The work aims at validation and assessment of the code to reproduce the observed phenomena and investigate about its limitations to predict complicated mixing phenomena between the subcooled emergency cooling water and the two-phase flow in the downcomer. The obtained results show that the overall trends of the main test variables are well reproduced by the calculations. In particular, the pressure in the primary system show excellent agreement with the experiment. The loop seal clearance phenomenon was observed in the calculation and it was found to have an important influence on the transient progression. Moreover, the collapsed water levels in the core are accurately reproduced in the simulations. However, the drop in the downcomer level before the activation of the DVI from safety injection tanks was underestimated due to multi-dimensional phenomena in the downcomer that are not properly captured by one-dimensional simulations.

• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.6
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• pp.601-609
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• 2000

Direct torque control(DTC) of AC motor has the fast torque and flux dynamic responses even though it has very simple scheme to implement. However, DTC do not show good performance at low speed range with conventional open loop stator flux observer when stator resistance varied. Therefore, authors propose a new nonlinear stator flux observer in order to estimate the stator flux of induction motor at low speed and show its simulation results.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.7
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• pp.343-348
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• 2020

So far, research into multinational bank' overseas expansion has focused on foreign direct investment in the financial services industry. However, this study focused its existing theories on multinational banks on decision-making related to the type of overseas advancement of local financial institutions. For research, four environmental factors were considered: the scale of foreign direct investment, the scope of financial services that can be provided according to the rules of the host country, the corporate tax rate of the host country, and the level of development of the host country's banking industry. Through Kotra, data on the total amount of claims from 2010 to 2014 and the regulatory status for the country's financial industries were obtained. Hypothesis are built around theories and survey factors and has been demonstrated through regression analysis. Results show that Korean financial institutions tend to expand as legally independent subsidiaries where the corporate tax rate of the host country is relatively low. Contrary to the previous studies based on the U.S. banking corporates, results show that Korean banks tend to expand in forms of branches to the host countries with high level of banking system development.

• International Journal of Industrial Entomology and Biomaterials
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• v.7 no.1
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• pp.15-20
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• 2003

The present investigation was carried out to study the possible cause for reciprocal difference in silkworm hybrids. By utilising the polyvoltine race Pure Mysore (PM) and newly evolved breeds (CSR2, CSR5, CSR16 and CSR17), the direct and reciprocal crosses of polyvoltine ${\times}$ bivoltine and also bivoltine hybrids were studied. The hybrids of polyvoltine ${\times}$ bivoltine (direct) are superior to their reciprocal crosses in respect of cocoon yield, cocoon weight and filament length. The reciprocal crosses of polyvoltine ${\times}$ bivoltine are superior to their direct crosses in respect of fecundity and short larval duration. No significant differences were observed in the characters like cocoon shell ratio, raw silk percentage, denier, reelability and neatness in both polyvoltine ${\times}$ bivoltine direct crosses and their reciprocals. The expression of cocoon characters as a function of sex revealed that direct crosses (polyvoltine ${\times}$ bivoltine) showed higher cocoon weight, pupal weight, shell weight and longer filament length in females than the reciprocal crosses (bivoltine ${\times}$ polyvoltine), where as these characters in males were almost the same in both direct and reciprocal crosses, indicating that the sex-linked genetic factor played a more important role. it was clear that difference in cocoon yield observed in reciprocal crosses of polyvoltine ${\times}$ bivoltine was due to the low cocoon and shell weight in females which was turn due to presence of early maturity genes (Lme) linked with sex-chromosome (X) which effect on larvae period of the silkworm. In bivoltine hybrids, i.e., both direct and their reciprocals crosses, all the characters viz., hatching percentage, larval duration, survival, cocoon weight, cocoon shell weight, cocoon shell ratio, raw silk percentage, filament length, denier, reelability and neatness did not show any significant difference (except number of eggs laid by moth) which could account for presence of same maturity genes (Lm) in both direct and reciprocal crosses. it was clear that reciprocal differences occur when the hybrids are prepared from the parental strains with different voltinism.

• Journal of the Korea Concrete Institute
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• v.15 no.2
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• pp.246-253
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• 2003

Although concrete members are not normally designed to resist direct tension, the knowledge of tensile strength is of value in estimating the cracking load. In general, there are three types of test method for tensile strength ; direct tension test, flexural tension test, and splitting tension test. Though direct tensile strength represents the real tensile strength of concrete, direct tension tests are seldom carried out, mainly because it is very difficult to applicate a pure tension force. The purpose of this paper is to investigate the test methods, effect of aspect ratio, and the size effect on the direct tensile strength. Direct tension test, using bonded end plates, follows RILEM and U.S.Bureau of Reclamation. And other test methods follow ASTM provisions. Four kinds of aspect ratio and two kinds of size effect are tested. Same variables are tested by direct tension test and splitting tension test for comparison between the two test methods. Test results show that direct tensile strength of concrete is more affected by aspect ratio and size than other kinds of strength.

• ETRI Journal
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• v.29 no.2
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• pp.135-142
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• 2007

The small anechoic chambers built by many small-/medium-sized companies and universities present difficulties in testing electrically large antennas because the chamber size cannot satisfy the far-field criterion of large antennas. In this paper, a method for Fresnel-region measurement on a cylindrical surface with variation of the measurement height is proposed and verified by both calculations and experiments. We implement the proposed method using a direct far-field measurement system by adding a few supporting structures. The results show good accuracy.

• Journal of the Korean Mathematical Society
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• v.35 no.2
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• pp.399-422
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• 1998

A useful method of proving the finite decidability of an equationally definable class V of algebras (i.e., variety) is to prove the decidability of the class of finite directly indecomposable members of V. The validity of this method relies on the well-known result of Feferman-Vaught: if a class K of first-order structures is decidable, then so is the class {$\prod$$_{i}$＜n/ $A_{i}$│ $A_{i}$ $\in$ X (i < n), n $\in$ $\omega$}. In this paper we show that the converse of this does not necessarily hold.d.d.

• 제어로봇시스템학회:학술대회논문집
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• 1987.10a
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• pp.851-856
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• 1987

A direct computation algorithm of two dimensional fast Fourier transform (2D-FFT) is considered here for implementation in mesh connected multiprocessor array of both a 2D-toroidal and a rectangular type. Results are derived for a hardware algorithm including data allocation and interprocessor communications. A performance comparison is carried out between the proposed direct 2D-FFT computation and the conventional one to show that a new algorithm gives higher speedup under a reasonable assumption on the speeds of operations.

• Journal of the Optical Society of Korea
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• v.18 no.2
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• pp.124-128
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• 2014

We derive joint probability density functions (JPDFs) for two adjacent data from direct-detection optical receivers in dense wavelength-division multiplexing systems. We show that the decision using two data per bit can increase the receiver sensitivity compared with the conventional decision. Our JPDFs can be used for software-defined optical receivers enhancing the receiver sensitivities for intensity-modulated channels.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.3
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• pp.69-72
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• 2012

It is well known that speed of a direct current shunt motor is inverse proportional to flux. This paper presents speed expression to show that speed is not inverse proportional to flux. The presented speed vs. flux curves are verified by experimental result that shows the need of the revision of speed vs. flux curves shown in conventional text books.