• Journal of The Korean Association For Science Education
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• v.1 no.1
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• pp.45-52
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• 1978

In order to normalized the Earth Science Education, experiments and geologic field trainings are very important. But it have not carried out on account of many difficulties in current High School of Korea. These difficulties are lack of time, many problems of the text book, heavy teaching load, shortage of facilities and experimental equipments, and poor quality of teacher etc. The practical training of geologic field trip is very important in Earth Science Education. Finally, wirter propose a new teaching plan of geologic field training as follows: 1. The teacher must prepare the guide paper of field geologic training. 2. Subjects of practical training must simplify. 3. The teacher must take a pre-field investigation in order to get the teaching plan and the preparation of practical field training. 4. Let students observe for themselves on this guide, as if they were geologists. 5. The teacher must conclude about practical training after the working.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.7 no.1
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• pp.33-39
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• 2007

Recently there are increasing needs for Internet and various kinds of contents. These traffics for various contents need more amount of data to provide high-quality information and require various QoS depending on the characteristics of contents. However, current Internet service supports BE (Best Effort) service only, therefore IntServ (Integrated Service) scheme and DiffServ (Differentiated Service) scheme are represented to support QoS in IP layer. This paper describes new scheme that provides QoS taking into account the traffic characteristics over Mobile IPv6 network based on IEEE 802.11e by decreasing signal process time using traffic class of DiffServ and MAC and evaluates the performance through computer simulation.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.8
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• pp.658-663
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• 2002

Hall factor of electrons in $\Gamma$-valley is calculated as functions of temperature, impurity concentration, and nonparabolicity of conduction valleys by taking into account the current density obtained from the Boltzmann transport equation. The dependence of the Hall factor on the temperature is clearly shown in the case of the optical phonon scattering and that on the impurity concentration is obvious in the case of the ionized impurity scattering. As the nonparabolicity of the conduction band increases, the Hall factor due to the acoustic or optic phonon scattering increases, whereas that due to the ionized impurity scattering decreases. The change of the Hall factor can be analysed in terms of the dispersion of relaxation time.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.6
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• pp.1-9
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• 1995

The structures of inductive irises are used commonly in waveguide filter, especially at highter frequencyies, due to low loss and high temperature stability. However, the iris thickness can not be neglected, as it could be at the lower frequencies. Approximate models assuming zero thickness fail to predict the exact behavior of the filter. And current thickness correction is introduced which is valid in the case of thick irises only. Account of the effect of round is normally not taken. So the necessity of finding a relation for the two factors-iris thickness and round-arises in the design of waveguide filters. This paper describes a mutual relation that considers the combined effect of finite thickness and round from the start. In order to test the validity of the changed relation, weveral examples are given. And the measured response of each case is then compared with the predicted reponse. And it is shown that the radius is of perceptible influence on the transmission coefficient through a thick iris.

• ETRI Journal
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• v.34 no.4
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• pp.536-541
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• 2012

This paper aims to extend the transmission line matrix method with a hybrid symmetrical condensed node (HSCN) to model ferrite media in the time domain. To take into account the anisotropy and dispersive properties of ferrite media, equivalent current sources are incorporated into supplementary stubs of the original HSCN. The scattering matrix of the proposed HSCN is provided, and the validity of this approach is demonstrated for both transversely and longitudinally magnetized ferrites. Agreement is achieved between the results of this approach and those of the theoretical and the finite-difference time-domain method.

• 한국가시화정보학회:학술대회논문집
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• 2004.11a
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• pp.30-33
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• 2004

In order to analyze the heat transfer phenomena in the plasma flames, a mathematical model describing heat and fluid How in an electric arc has been developed and used to predict heat transfer from the arc to the steel bath in a DC Electric Arc Furnace. The arc model takes the separate contributions to the heat transfer from each involved mechanism into account, i.e. radiation, convection and energy transported by electrons. The finite volume method and a SIMPLE algorithm are used for solving the governing MHD equations, i.e., conservation equations of mass, momentum, and energy together with the equations describing a standard $k-\varepsilon$ model for turbulence. The model predicts heat transfer for different currents and arc lengths. Finally these calculation results can be used as a useful insight into plasma phenomena of the industrial-scale electric arc furnace. from these results, it can be concluded that higher arc current and longer arc length give high heat transfer.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.381.1-381
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• 2002

The A lot of rotating machinery are generally used in industrial field and the electrical machinery such as the motor and generator account for the most of the part. Generally motor and generator have electrical loss because of eddy current. So silicon steel sheets are used in order to reduce the electrical loss and furthermore laminated rotor is used for motor and generator to eliminate the electrical loss and heat generation. (omitted)

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.4
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• pp.418-424
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• 2009

This work is the attempt to give qualitative explanations to complex magnetic phenomena which are observed in the previously proposed magnetostrictive sensor capable of ultrasonic waves and rotational speed measurement. The law of approach is adopted as analysis tool in order to account for some extraordinary output patterns and proved to be effective. The distance between the anhysteretic curve current magnetic state and the variation of anhysteretic curve by stress mainly determine the sensor output shapes and their uniqueness. It is also experimentally verified that the precisely determined bias magnetic field strength can not only remove the unusual output parts but also maximize its sensitivity.

• JSTS:Journal of Semiconductor Technology and Science
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• v.13 no.5
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• pp.530-537
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• 2013

An explicit surface potential calculation method of gate-all-around MOSFET (GAAMOSFET) devices which takes into account both interface trap charge and varying doping levels is presented. The results of the method are extensively verified by numerical simulation. Results from the model are used to find qualitative and quantitative effect of interface trap charge on subthreshold slope (SS) of GAAMOSFET devices. Further, design constraints of GAAMOSFET devices with emphasis on the effect of interface trap charge on device SS performance are investigated.

• Asia-Pacific Journal of Business
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• v.9 no.2
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• pp.59-74
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• 2018

It is well known that market transactions do not lead to social optima when externalities exist. Given that previous studies such as RICARDO-AEA(2014) have identified various types of external costs, we must take their magnitudes, or externalities in general, into account in order to make toll prices to achieve social optimum. Little has been done on estimation of externalities in road uses in Korea, to the best of our knowledge. We suggested to use the contingent valuation method (CVM) to estimate overall social benefits and applied it to estimation of benefits of road kill prevention as a pilot study. Our empirical model has considered heteroskedasticity explicitly and its estimation result was that individual drivers were willing to pay 147 KRW on average in addition to current toll prices for prevention of road kills. We provided general discussions of externalities in road use and various internalization measures.