• Agricultural and Biosystems Engineering
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• v.1 no.2
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• pp.67-72
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• 2000

A dynamic draft model is necessary to analyze mechanics of tillage and to design optimal tillage tools. In order to deal with draft dynamics, a neural network paradigm was applied to develop dynamic draft models. For the development of the models, three kinds of tillage tools were used to measure drafts in the soil bin and a time lagged recurrent neural network was developed. The neural network had a structure to predict dynamic draft, having a function of one-step-ahead prediction. A procedure for network prediction model identification was established. The results show promising modeling of the dynamic drafts with developed neural network.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.10 no.5
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• pp.535-549
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• 1998

A numerical study for performance analysis of a counterflow type forced draft tower and natural draft cooling tower has been performed based on the method using the finite volume method with non-orthogonal body fitted and non-staggered grid system. For solving the coupling problem between water and air, air enthalpy balance, moisture fraction balance, water enthalpy balance, and water mass balance equations are solved with Navier-Stoke’s equations simultaneously. For the effect of turbulence, the standard k-$\varepsilon$ turbulent model is implied in this analysis. The predicted result of the present analysis is compared with the experimental data and the commercial software result to validate the present study, The predicted results show good agreement with the experimental data and the commercial software result. To investigate the influence of the cooling tower design parameters such as approach, range and wet bulb temperature, parametric studies are also peformed.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.20
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• pp.467-493
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• 2003

There are situations in e-commerce that are altogether new and to which the existing rules cannot apply. The uncertainty and business risk is too high for trading partners to deal with certainty. Therefore existing law must be changed to e-commerce law so that it provides certainty and enforceability in the e-commerce. Legal rules applying to the commerce and international commerce, in particular, contracts, proper law, jurisdiction and so on, have improved with time and experience. It has been found that the problems arising in the context of e-contracting were due to the absence of experience in electronic contracting and an absence of knowledge on how best to solve the problems. Thus, UNCITRAL Working Group on Electronic Commerce held an extensive discussion on issues related to electronic contracting and prepared and revised the Preliminary Draft Convention on International Contracts Concluded or Evidenced by Data Message from the thirty-ninth session in 2002 and prepared the Draft Convention from forty-first session which applies to international contracts concluded or evidenced by means of data messages. An electronic contract is concluded when the acceptance of an offer becomes effective, and an offer becomes effective when it is received by the offeree, and an acceptance of an offer becomes effective when the indication of assent is received by the offeror according to this Convention. Electronic contract may be concluded by the interaction of an automated computer system and natural person or by the interaction of automated computer systems, and a contract formed by a natural person that accesses an automated computer system of another person has no legal effect in case the neutral person made a material error in a data message. The purpose of this paper is to raise the understanding of the Convention on the Electronic Contracting by studying the contents of Draft Convention on Electronic Contracting and comparing Draft Convention with preliminary Draft Convention and finding the difference, characteristics and problem.

• Journal of Power System Engineering
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• v.13 no.6
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• pp.88-94
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• 2009

In this paper, vibration characteristics after applying variable speed control to fans with a rated speed used in a power plant are studied by performing experiments and analyzing finite element models. Then the campbell diagram is presented to verify the reason of the abnormal vibration measured from fan structure during variable operation of Forced Draft Fan & Induced Draft Fan. According to results, it is found that amplitude of acceleration increases abruptly when a 2X harmonic component meets the natural frequency of fan rotor. Therefore it is very important thing that investigate exactly dynamic characteristics for the rotor at variable speed zone before applying variable speed control to a rotor with a rated speed.

• Journal of Power System Engineering
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• v.14 no.5
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• pp.30-35
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• 2010

Recently, the large capacity draft fans in power plants had been changed to variable speed type to educe the power consumption. But the fan experienced the unexpected vibration at specific speed regions. In this study, the high vibration frequency of the fan was confirmed and the natural frequency of the rotor were measured and analyzed by FEM programs. It was analyzed that the vibration was caused by the resonance at the frequency, 30.7Hz. So, the rotor vibration characteristic was changed by adjusting the distance between the shaft bearings. It was conformed the high vibration was disappeared over the all operation speeds.

• International Journal of Fluid Machinery and Systems
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• v.8 no.3
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• pp.202-208
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• 2015

For a prototype turbine operating under part load conditions, the turbine output is fluctuating strongly, leading to the power station incapable of connecting to the grid. The field test of the prototype turbine shows that the main reason is the resonance between the draft tube vortex frequency and the generator natural vibration frequency. In order to reduce the fluctuation of power output, different measures including the air admission, water admission and adding flow deflectors in the draft tube are put forward. CFD method is adopted to simulate the three-dimensional unsteady flow in the Francis turbine, to calculate pressure fluctuations in draft tube under three schemes and to compare with the field test result of the prototype turbine. Calculation results show that all the three measures can reduce the pressure pulsation amplitude in the draft tube. The method of water supply and adding flow deflector both can effectively change the frequency and avoid resonance, thus solving the output fluctuation problem. However, the method of air admission could not change the pressure fluctuation frequency.

• The Korean Journal of Pesticide Science
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• v.18 no.1
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• pp.48-51
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• 2014

Since the year of 2006 when the extended revision of the Codex Classification of Foods and Animal Feeds was undertaken, considerable progresses have been made in revising the Classification. This paper aimed to summarize the present status on revision of the Codex Classification of Foods and Animal Feeds, focusing remarkable achievements such as 1) the draft revision of the Codex Classification for the fruit commodity group and 2) the draft Principles and Guidance on the Selection of Representative Commodities for the Extrapolation of Maximum Residue Limits for Pesticides to Commodity Groups, adopted by the Codex Alimentarius Commission in 2012. Additionally, it included information on lists of crop group or subgroup which are holding at Step 7 and were adopted at Step 5, and further have not been yet discussed by the Codex Committee on Pesticide Residues. These information will be very helpful for a pesticide regulatory regime.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.4 no.2
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• pp.119-128
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• 1975

Natural draft and flow which low temperature moist gas produces in the chimney of an Ondol heating system were numerically analysed. Among several factors involved inlet gas temperature has the strongest influence on the chimney performance and then next specific humidity of the gas. Thermal conductivity of the chimney wall, however, has little influence on the performance of such a low temperature chimney. Under given flow conditions there exists an optimum chimney height which gives a maximum flow rate for a given chimney diameter. This optimum value of chimney height inereases with increase in chimney diameter, inlet gas temperature and specific humidity.

• Nuclear Engineering and Technology
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• v.27 no.3
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• pp.281-291
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• 1995

The objective of this work is to obtain the experimental data for the heat transfer processes occurring both on the inside and outside surfaces of containment steel wall with dry and wet outer surface conditions in the passive containment cooling system. The test model represented a 60$^{\circ}$ section of a containment vessel based on the AP 600 geometry. Major linear dimensions of the test model ore reduced tv a factor of ten. To simulate the decay heat a steam generator heated by electricity was placed in the test model. The maximum heat flux was 8.91 kW/$m^2$. Two types of tests were performed. The one was the tort on the natural convection of air without water film flow. The other was the evaporative heat transfer test with the falling water film flow and natural air draft. no test result shooed that the heat transfer capability by the natural convection from the containment to the air without oater film flow was limited at about 1.48 kW/$m^2$ heat flux. It was found that the heat removal capability was remarkably enhanced in the tests with the waster film flow and air draft. The obtained heat transfer data ore compared with the existing correlations.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2004.11a
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• pp.195-199
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• 2004

The purpose of this study is to grasp the foundation and development of perimeter block housing in Berlin. The results of this study is as follows : Perimeter block housing in Berlin have been developed from small laborer house to gradually large- scale housing. The court used for natural lighting and draft, have been developed to a space for resident community or individual garden.