• Resources Recycling
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• v.26 no.3
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• pp.17-25
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• 2017

Electric arc furnace steelmaking dust has various physicochemical properties as volatile components generated in the melting process of steel scraps in an electric arc furnace, which is captured in oxide form as fine powder by reacting with oxygen in the air. In order to efficiently recycle these electric arc furnace dust, a kinetic basic experiment and a pilot production test were carried out in parallel. As a result, it was found that the electric arc furnace dust contain a large amount of Cl and alkali components, thus it was expected that the compounds have a great adverse effect on the actual operation for the recycling. It was confirmed that the volatilization behavior was progressing actively at $1100^{\circ}C$ and the electric arc furnace dust was melted at $1250^{\circ}C$. These results are the same as a result of pilot test for the formation behavior of zinc oxide and reduced iron. These results should be useful as basic data for designing the recycling plant of the electric arc furnace dust and establishing the operating conditions.

• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.2
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• pp.71-82
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• 1984

A programme, called BIPOLE, for the numerical analysis of twotimensional n-p-n bipolar transistors was developed. It has included the SRH and Auger recolnbination processes, the mobility dependence on the impurity density and the electric field, and the band-gap narrowing effect. The finite difference equations of the fundamental semiconductor equations are formulated using Newton's method for Poisson's equation and the divergence theorem for the hole and electron continuity equations without physical restrictions. The matrix of the linearized equations is sparse, symmetric M-matrix. For the solution of the linearized equations ICCG method and Gummel's algorithm have been employed. The programme BIPOLE has been applied to various kinds of the steady-state problems of n-p-n transistors. For the examples of applications the variations of common emitter current gain, emitter and diffusion capacitances, and input and output characteristics are calculated. Three-dimensional representations of some D.C. physical quantities such as potential and charge carrier distributions were displayed. This programme will be used for the nome,rical analysis of the distortion phenom ana of two-dimensional n-p-n transistors. The BIPOLE programme is available for everyone.

• Journal of The Korean Association For Science Education
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• v.37 no.4
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• pp.693-703
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• 2017

In this study, 37 elementary, middle, and high school science teachers attending graduate schools of education were surveyed about their thoughts about the difficulty of teaching science units and teaching methods to teach these units to students. After experiencing the activity of making new teaching tools using scratch, we tried to confirm the development of TPACK among the teachers. Through the questionnaire survey for elementary, secondary, and high school science teachers, we selected the unit of Planetary Movement of the Solar System as a unit that is difficult for teachers to teach. We gave them the experience of instruction on tool making process for implementing a planetary operation model using scratch. Then, based on the questionnaires and class presentations, we analyzed the change of awareness about technology introduction and the development of their TPACK. As a result, most of the teachers showed changes of perceptions related to TK, TCK, TPK; the use of programming for creating teaching materials enhances teachers' understanding of the teaching contents; the teachers were convinced that students would develop the ability to construct models that fit observational phenomena; they thought that there would be a positive educational effect in the positive domain.

• Microbiology and Biotechnology Letters
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• v.31 no.4
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• pp.311-321
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• 2003

Bacteria produce lipases, which can catalyze both the hydrolysis and the synthesis of long chain triglycerides. These reactions usually proceed with high regioselectivity and enantioselectivity, and, therefore, lipases have become very important biocatalysts used in organic chemistry. 3D lipase structures were solved from several bacterial lipases. They have an $\alpha/\beta$ hydrolase fold and a catalytic triad consisting of a nucleophilic serine, and an aspartate or glutamate residue that is hydrogen bonded to a histindine. Active sites are covered with $\alpha$-helical lid structure, of which movement is involved in the enzyme's activation at oil/water interface. Four substrate binding pockets were identified for triglycerides: an oxyanion hole and three pockets accommodating the fatty acids bound at positions sn-1, sn-2, and sn-3. These pockets determine the enantiopreference of a lipase. The understanding of structure-function relationships as well as the development of molecular evolution techniques will enable researchers to tailor new lipases for biotechnological applications.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.7
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• pp.641-655
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• 1992

In this paper, the performance of the various multiple accesstechniques for the mobile computer network has been studied in the consideration of the characteristics. Of the mobile communication channel. In the case of the hidden node occurring, it could be seen that the performance of the code division multiple access(CDMA) technique. With simultaneous access function is better than that of the other packet access methods such as carrier sensed multiple access(CAMA). Busy tone mulitiple access(BTMA)and idle signal muitiple access(ISMA) in the view of the throuhtput and mean delay time. Also it has been shown that the performance of the CDMA method is superior to that of other packet access techniques such as multiple access(CSMA).etc when the fading effect or impulsive noise exists in the mobile channel. Especially in the case of the distributed mobile network. It has been shown that the receiver-transmitter based CDMA method using the characteristics of CDMA effectively has better throughput and less mean delay time than the commontransmitter based CDMA technique.

• KIPS Transactions on Computer and Communication Systems
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• v.7 no.9
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• pp.235-242
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• 2018

Various technologies have been developed to more efficiently share content such as P2P, CDN, and CCN. These technologies take a common approach that content request packets is responded by distributed network nodes or hosts, not by a single content distributor. Such approaches not only resolve network congestion around content distributors, but also make it possible to distribute content regardless of the system and network status of content distributors. However, when receiving content from distributed nodes/hosts, not from authenticated distributors, users cannot practically identify which node/host sent content to them. Due to this characteristic, various hacking caused by the malicious modification of content is possible. Therefore, to make such approaches more secure, a content authentication technique is required. In this paper, we propose a improved operation of MHT used in CCN for authenticating distributed content. Then we evaluate the proposed method by comparing its performance with the existing technology.

• Journal of Advanced Navigation Technology
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• v.10 no.3
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• pp.256-262
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• 2006

This paper proposes a new predistortion linearizer to compensate for AM/AM and AM/PM in the nonlinear characteristics of amplifier. This consists of common-emitter amplifier and schottky diode that is connected between emitter and ground. When effective resistance of the schottky diode with bias condition varies, common-emitter amplifier with series feedback has a increase of amplitude and expansion of phase. This makes a amplifier nonlinear characteristics are to be improved. The proposed linearizer and amplifier has been manufactured and tested to operate in cellular base station frequency (869~894MHz). The test results show that third order intermodulation distortion (IMD3) cab be removed by more than 10.4dB in case of CW 2-tone signals ${\Delta}f$=1MHz, and the adjacent channel power ratio (ACPR) also can be improved by more than 9.6dB for CDMA IS-95 1FA signals.

• Journal of Korean Classical Literature and Education
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• no.33
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• pp.255-283
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• 2016

There are different variations in folktales. Sometimes folkltales are combined with another folktales. This is probably done to make it an object-oriented narrative in which an epic attempt is made to strengthen an issue that was not resolved earlier, or a context that was not completed. The wood cutter and the heavenly maiden and Snail bride, are commonly noted for their gender relationship. These tales represent issue of continuing relationships between men and women. Particulary, how in the process of doing so, they succumb to their desires. This striving for lasting relationships does not end happily because "the man" in each case was immature and not able to think clearly. Other folktales were combined with these tales to resolve this problem. The man was transformed into a mature person and the wrongdoer's excessive greed was punished. The narrative of the folktales was changed to bring out the epic of growth, or the epic of punishment. This can be understood through the concept of narrative scheme. Folktale combinations in narrative schemes can be used effectively in narrative education.

• Journal of Korea Port Economic Association
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• v.31 no.2
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• pp.1-21
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• 2015

This study verifies the change in market conditions in the Korea-China and Korea-Japan car ferry routes. Variation in historical development has led to differences in the lifecycle stages of these two car ferry shipping markets. However, previous studies have focused on individual car ferry routes rather than offering a more general understanding of this market. Based on the foregoing, we investigate the international car ferry market conditions from/to Korean ports, assess the management performances of car ferry companies, analyze the lifecycle stages of each car ferry route, and offer insights into the future of these markets. We show that the competitive market conditions and demands of passengers and cargoes differ between these routes. As for the market stage, we conclude that the Korea-China route is entering a mature market, whereas the Korea-Japan route is entering a declining stage.

• Food Engineering Progress
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• v.21 no.4
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• pp.332-340
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• 2017

This study investigated the changes in the physicochemical properties of soybean sprout, radish, and pork loin during frozen Bibimbab production. The qualities of soybean sprout were affected by the blanching, thawing, and cooking processes, with the blanching process particularly regarded as an important process to attribute the overall quality of the soybean sprouts in the final product. High weight loss of radish was found in the thawing and cooking processes, while the weight loss was relatively lower than that of soybean sprout. However, mixing with hot rice can be attributed for the steep decrease in shear force of the radish. For pork meat, normally thermal treatment such as mixing with hot rice and cooking manifested quality deterioration. Based on the results, mixing process appeared to be the most important process which affected the final quality of the materials. To improve the quality of final frozen Bibimbab, therefore, it was recommended to freeze the food ingredient separately from rice prior to packaging, which warranted the follow up exploration.