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Chemical Analysis and Thermoelectric Properties of the PbSnTe Semiconductors (화학조성에 따른 PbSnTe계 반도체의 열전특성조사)

  • Oh, Kyu-Whan;Oh, Seung-Mo
    • Applied Chemistry for Engineering
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    • v.1 no.1
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    • pp.83-90
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    • 1990
  • The semiconducting $(Pb_1\;_xSn_x)_1$ $_yTe_y$, one of the low - temperature thermoelectric materials, has been prepared and its chemical composition and nonstoichiometry has been analyzed. The content of Pb in the specimens was determined by the complexometric back - titration method with EDTA and Pb(II) standard solutions. Te - content was analyzed with the redox titration method. The electrical conductivity and the thermoelectric power have also been measured by the DC 4 - probe and the heat-pulse technique, respectively. All of the specimens showed a nonstoichiometric behavior in their chemical compositions (Te excess), thus gave rise to a p - type semiconducting property, and the nonstoichoimetry became bigger as the Sn - content increased. The thermoelectric power vs. temperature results have been analyzed upon the basis of the Fermi level vs. temperature profiles in the saturation regime. The specimen of x=0.1 evolved a transition from p - to n - type property at about 670K, which has been explained by the fact that the mobility of electrons is bigger than that of holes in the temperature range of the intrinsic regime.

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Contested Technologies, Resetting the Boundary, and the "signifiant-politics": Semiotical Governance of New Technology in the Case of fMRA (경합하는 기술, 경계의 재설정, 그리고 기표-정치(signifiant-politics): 기능성자기공명혈관조영술(fMRA)의 사례로 살펴본 신기술의 명명 작업)

  • Lee, June-Seok
    • Journal of Science and Technology Studies
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    • v.14 no.2
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    • pp.199-222
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    • 2014
  • Functional Magnetic Resonance Angiography (fMRA) was a technoscientific innovation that allows scientists to directly view the changes made in the blood vessels of a brain. fMRA was first developed at Neuroscience Research Institute (NRI) in Korea. fMRA mainly utilizes 7 Tesla MRI technology, and NRI is equipped with the instrument. First article on fMRA was published in 2008, and two more papers in 2010 and 2012 consecutively had been published on the newly developed technique. However, fMRA is a competitive technology with existing fMRI. Both techniques capture microvascular changes in a brain, and by doing it, both techniques visualize the cognitive and affective changes. fMRI technology was introduced by Seiji Ogawa in the early 1990's and has been widely used since then. In contrast, fMRA was a newer technology and rather unknown. Developers of fMRA in NRI used series of signifiant-politics in order to make it better known to scientific community as well as public. By resetting the boundaries of existing concept of fMRI, they tried to lower the threshold of a new concept/technique. This case study shows how technoscientists use semiotic strategies governing new technology.

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A Design and Implementation of Busbar Joint and Temperature Measurement System (부스바 접촉 상태 및 온도 감지 시스템 설계 및 구현)

  • Lee, Young-dong;Jeong, Sung-Hak
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.21 no.2
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    • pp.379-385
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    • 2017
  • In general, distribution board, panel board and motor control center can be installed over a wide area such as residence of group, building, schools, factories, ports, airports, water service and sewerage, substation and heavy industries that are used to supply converts the voltages extra high voltage into optimal voltage. There are electrical accidents due to rise of contact temperature, loose contact between busbar, deterioration of the contact resistance, over temperature of the busbars. In this paper, we designed and implemented the busbar joint and temperature measurement system, which can measure the joint resistance of busbar and loose connection between busbar using potentiometer and non-contact infrared sensor. The experimental results show that tightening the bolt and nut is fully engaged, resistance was decreased and maximum error range was 0.1mm. Also, the experimental result showed that the temperature at the contact area is increased from $27.3^{\circ}C$ to $69.3^{\circ}C$by the contact resistance.

Philippines 2017: Warlike Powers of Security Forces and Hedging Strategies in Foreign Relation (필리핀 2017: 호전적 내치(內治)와 줄타기 외교)

  • KIM, Dong-Yeob;JUNG, Bub Mo
    • The Southeast Asian review
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    • v.28 no.2
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    • pp.181-212
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    • 2018
  • In 2017, the government of Duterte, in the second year of the ruling, more strongly promoted peace and order policies and expressed independent diplomacy as the chairman of ASEAN. He continued to fight against drugs and tried to increase his political legitimacy through the punishment for corrupt officials. He also declared martial law in the Mindanao region because of the dissolution of the Maute group, a Muslim terrorist organization, and strengthened counterterrorism cooperation externally. In addition, as to Communist militants, he took the initial reconciliation gesture and promoted peace negotiations, however, concluded the peace tide and started the suppression operation due to a series of bloodshed. He still has a strong drive in peace and order issues, backed up by high support rate, but it is becoming a factor of anxiety as the socioeconomically underprivileged and minority groups are increasingly alienated. As the chairman of ASEAN, Duterte has a certain distance from the United States, which is a firm ally, but has turned to increase familiarity with China and Russia, which can take substantial economic benefits. Through diversifying the external economic support and increase of tax revenue, the priority task was to establish the infrastructure. Although the Philippines, which has a high economic growth rate, has a strong expectation that it can establish a solid infrastructure, tax reforms should be successfully completed in order not to repeat the previous failures, which has traditionally increased foreign debt burden by relying on external resources. It seems that it is necessary to find the meeting point of the foreign policy of Duterte and new Korean government's New Southern Policy, and to find possible economic cooperation policies to improve Philippine infrastructure.

Rhetorical Analysis of News Editorials on 'Screen Quota' Arguments: An Application of Toulmin's Argumentation Model (언론의 개방담론 논증구조 분석: 스크린쿼터제 관련 의견보도에 대한 Toulmin의 논증모델과 Stock Issue의 적용)

  • Park, Sung-Hee
    • Korean journal of communication and information
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    • v.36
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    • pp.399-422
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    • 2006
  • Whether to reduce the current 'screen quota' for domestic films in conjunction with the FTA discussions between Korea and the United States is one of the hotly debated issues in Korea. Using Toulmin's Argumentation Model, this study attempts to trace the use of data and warrants for each pro and con claims as portrayed in newspaper editorial columns and to find its rhetorical significance. A total of 67 editorial columns were collected from 9 nationwide news dailies in Korea for the purpose. The rhetorical analysis of those articles showed that the major warrants used in each pro and con opinion were absent of the potential issues of the opponents, which inherently fails to invite rebuttals from the opposite sides. This conceptual wall in each argumentation models implies an inactive conversation and subsequent absence of clash between the pro and con argumentation fields. It is thus suggested for opinion writers to find more adequate evidences to support the data and warrants to hold persuasive power of their respective claims, ultimately to enhance the public discourse among citizens.

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