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Preliminary Study on Actuated Signal Control at Rural Area of Cheon-an City (천안시 외곽지역의 감응식 신호운영을 위한 기초연구)

  • Park, Soon-Yong;Kim, Dong-Nyong
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.8 no.3
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    • pp.52-63
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    • 2009
  • Recently in Korea, in the case of metropolis, the urban signalized intersections are controlled by traffic information center or ITS center. Cheon-an City also established traffic information center through the 1st.-$\sim$3rd. ITS public construction and has managed this center that includes bus information service, traffic information collection and providing service, parking information service, and traffic responsive control system. In the Cheon-an metropolitan traffic signal operation, traffic signal controllers were grouped by the each main traffic flow axes and performed with coordinated signal timing for the signalized arterials, and also cycle and split changed by realtime traffic demands. Cheon-an urban traffic responsive control system was evaluated by intersection delay and speed, then it was verified that the delay decreased and vehicle speed improved. However, the rural signal control system to connect adjacency town was evaluated to have lower status than urban area due to the unimproved TOD (Time of day) plan. Therefore actuated signal control was examined for substitutive control system in isolated signal intersection. The aim of this article is to compare actuated signal control with TOD mode in the rural intersection of Cheon-an and to fine superiority of these two control mode, with evaluation of vehicle delay by using HCM(2000) method and by micro-simulation CORSlM. The result of field test show that actuated signal control gave better performance in delay comparison than the existing TOD signal control. And simulation outcome verified that non-optimized TOD has higher delay than optimized TOD mode, non-optimal actuated mode, and optimal actuated signal control mode. Particularly, these three modes delays had not different values according to the paired sample t-test. This is because small traffic demands were loaded in each links. This suggested actuated signal control is expected to be more effective than TOD mode in some rural isolated intersections which frequently need to survey for traffic volume.

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Effects of Dropwort Powder on the Quality of Castella (미나리가루의 첨가가 Castella의 품질에 미치는 영향)

  • Park, Sang-Jun;Lee, Kwang-Suck;An, Bye-Lyung
    • Journal of the East Asian Society of Dietary Life
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    • v.17 no.6
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    • pp.834-839
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    • 2007
  • This study was designed to determine the optimal ratio of dropwort powder in castella by adding the powder at levels of 0, 3, 6, 9, and 12% respectively. The properties of the castella were analyzed by specific gravity, specific volume, color determinations, texture properties and sensory evaluation. The Specific gravity increased with increasing amount of dropwort powder. However, the specific volume decreased with increasing dropwort powder. For the color values, as more dropwort powder was added, the L-value decreased. The castella with 9% dropwort powder had a higher hardness, gumminess, and chewiness. A sensory panel perceived that the external and internal color of the castella become darker with the dropwort powder substitution and the grain size decreased with increasing amount dropwort powder, while sweet taste showed no significant difference. The order of overall preference was DP 9>DP 6>DP 12>CON>DP 3. Therefore, the substitution of 9% of wheat flour with dropwort powder was recommended in the production of castella.

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Interpretation of Soil Catena for Agricultural Soils derived from Sedimentary Rocks (퇴적암 유래 농경지 토양에 대한 카테나 해석)

  • SONN, Yeon-Kyu;LEE, Dong-Sung;KIM, Keun-Tae;HYUN, Byung-Keun;JUN, Hye-Weon;JEON, Sang-Ho
    • Journal of the Korean Association of Geographic Information Studies
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    • v.20 no.4
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    • pp.1-14
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    • 2017
  • In Korea, the soil series derived from sedimentary rocks are classified into seven soil series of coarse loamy soil such as Dain, Danbug, Dongam, Imdong, Jeomgog, Maryeong, and Yonggog; seventeen soil series of fine loamy soil such as Angye, Anmi, Banho, Bigog, Deoggog, Dogye, Dojeon, Gamgog, Gugog, Jincheon, Maji, Mungyeong, Oggye, Samam, Yanggog, Yeongwol, and Yulgog; six soil series of fine silty soil such as Goryeong, Bonggog, Juggog, Gyeongsan, Yuga, and Yugog; and four soil series of clayey soil such as Mitan, Pyeongan, Pyeongjeon, and Uji. All thirty-four soil series have different drainage rates and topography. However, the soil texture depends on the parent rock. The buffer functions in GIS (Geographic Information System) techniques were used to calculate adjacent soil series from a soil series. The length of the adjacent soil series was adjusted because a side of the buffer area was one meter long. The cluster analysis was conducted using the CCC (Cubic Clustering Criterion) method, in which the number of clusters is calculated based on the individual soil series ratio. Soil survey has been carried out since 1964 as "The reconnaissance soil survey", and 1:5,000 detailed soil survey was completed in 1999 with a five-years plan in Korea. Today, all the soil survey information has been computerized. GIS techniques were used to establish a digital soil map; however, there have not been any studies to interpret pedogenesis using the GIS technique. In this study, the area of the adjacent soil series were obtained using the GIS technique. The area of the adjacent soil series can be calculated based on the information area. The similarities of soil originated from sedimentary rocks were estimated using the length. As a result, the distribution of grain size was different based on the types of sedimentary rocks and the location. The clusters were distinguished into limestone, sandstone, and shale. In addition, the soil derived from shale was divided into red shale and gray shale. This means that quantitative interpretation of the catena and this established method can be used to interpret the relationship between soil series.

Protective Effects on A2Kb Transgenic Mice That Were Immunized with Hepatitis B Virus X Antigen Peptides by the Activation of CD8+ T Cells; XEP-3 Specific CTL Responses in the in vitro Culture (B형 간염 바이러스 X 항원을 면역한 A2Kb Transgenic Mice에서 CD8+ T Cell의 활성화에 의한 X 항원 표현 재조합 Vaccinia Virus에 대한 방어 효과; in vitro 배양을 통한 XEP-3 특이적인 CTL의 반응)

  • Hwang, Yu Kyeong;Kim, Hyung-Il;Kim, Nam Kyung;Park, Jung Min;Cheong, Hong Seok
    • IMMUNE NETWORK
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    • v.2 no.1
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    • pp.41-48
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    • 2002
  • Background: Viral antigens presented on the cell surface in association with MHC class I molecules are recognized by CD8+ T cells. MHC restricted peptides are important in eliciting cellular immune responses. As peptide antigens have a weak immunigenicity, pH-sensitive liposomes were used for peptide delivery to induce effective cytotoxic T lymphocyte (CTL) responses. In the previous study, as the HBx peptides could induce specific CTLs in vitro, we tested whether the HLA-A2/$K^b$ transgenic mice that were immunized by HBx-derived peptides could be protected from a viral challenge. Methods: HBx-peptides encapsulated by pH-sensitive liposomes were prepared. $A2K^b$ transgenic mice were immunized i.m. on days one and seven with the indicated concentrations of liposome-encapsulated peptides. Three weeks later, mice were infected with $1{\times}10^7pfu$/head of recombinant vaccinia virus (rVV)-HBx via i.p. administration. The ovaries were extracted from the mice, and the presence of rVV-HBx in the ovaries was analyzed using human TK-143B cells. IFN-${\gamma}$ secretion by these cells was directly assessed using a peptide-pulsed target cell stimulation assay with either peptide-pulsed antigen presenting cells (APCs), concanavalin A ($2{\mu}g/ml$), or a vehicle. To generate peptide-specific CTLs, splenocytes obtained from the immunized mice were stimulated with $20{\mu}g/ml$ of each peptide and restimulated with peptide-pulsed APC four times. The cytotoxic activity of the CTLs was assessed by standard $^{51}Cr$-release assay and intracellular IFN-${\gamma}$ assay. Results: Immunization of these peptides as a mixture in pH-sensitive liposomes to transgenic mice induced a good protective effect from a viral challenge by inducing the peptide-specific CD8+ T cells. Mice immunized with $50{\mu}g/head$ were much better protected against viral challenge compared to those immunized with $5{\mu}g$/head, whereas the mice immunized with empty liposomes were not protected at all. After in vitro CTL culture by peptide stimulation, however, specific cytotoxicity was much higher in the CTLs from mice immunized with $5{\mu}g/head$ than $50{\mu}g/head$ group. Increase of the number of cells that intracellular IFN-${\gamma}$ secreting cell among CD8+ T cells showed similar result. Conclusion: Mice immunized with XEPs within pH-sensitive liposome were protected against viral challenge. The protective effect depended on the amount of antigen used during immunization. XEP-3-specific CTLs could be induced by peptide stimulation in vitro from splenocytes obtained from immunized mice. The cytotoxic effect of CTLs was measured by $^{51}Cr$-release assay and the percentage of accumulated intracellular IFN-${\gamma}$ secreting cells after in vitro restimulation was measured by flow cytometric analysis. The result of $^{51}Cr$-release cytotoxicity test was well correlated with that of the flow cytometric analysis. Viral protection was effective in immunized group of $50{\mu}g/head$, while in the in vitro restimulation, it showed more spectific response in $5{\mu}g$/head group.

Digital Hologram Compression Technique By Hybrid Video Coding (하이브리드 비디오 코팅에 의한 디지털 홀로그램 압축기술)

  • Seo, Young-Ho;Choi, Hyun-Jun;Kang, Hoon-Jong;Lee, Seung-Hyun;Kim, Dong-Wook
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.42 no.5 s.305
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    • pp.29-40
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    • 2005
  • According as base of digital hologram has been magnified, discussion of compression technology is expected as a international standard which defines the compression technique of 3D image and video has been progressed in form of 3DAV which is a part of MPEG. As we can identify in case of 3DAV, the coding technique has high possibility to be formed into the hybrid type which is a merged, refined, or mixid with the various previous technique. Therefore, we wish to present the relationship between various image/video coding techniques and digital hologram In this paper, we propose an efficient coding method of digital hologram using standard compression tools for video and image. At first, we convert fringe patterns into video data using a principle of CGH(Computer Generated Hologram), and then encode it. In this research, we propose a compression algorithm is made up of various method such as pre-processing for transform, local segmentation with global information of object image, frequency transform for coding, scanning to make fringe to video stream, classification of coefficients, and hybrid video coding. Finally the proposed hybrid compression algorithm is all of these methods. The tool for still image coding is JPEG2000, and the toots for video coding include various international compression algorithm such as MPEG-2, MPEG-4, and H.264 and various lossless compression algorithm. The proposed algorithm illustrated that it have better properties for reconstruction than the previous researches on far greater compression rate above from four times to eight times as much. Therefore we expect that the proposed technique for digital hologram coding is to be a good preceding research.

Study on the Vitrification of Human Blastocysts: II. Effect of Vitrification on the Implantation and the Pregnancy of Human Blastocysts (인간 포배기 배아의 초자화 동결에 관한 연구: II. 초자화 동결이 포배기 배아의 착상 및 임신에 미치는 영향)

  • Kim, Su-Hee;Lee, Sang-Won;Lee, Ju-Hee;Kang, Sang-Min;Oh, Hee-Jeong;Lee, Seoung-Min;Lee, Seong-Goo;Yoon, Hye-Gyun;Yoon, San-Hyun;Park, Se-Pill;Song, Hai-Bum;Lim, Jin-Ho
    • Clinical and Experimental Reproductive Medicine
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    • v.27 no.1
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    • pp.67-74
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    • 2000
  • Objective: This study was conducted to investigate the effect of vitrification on the implantation and the pregnancy of human blastocysts. Method: The transfer of the frozen-thawed blastocysts by the slow freezing or vitrification was performed between January 1998 and July 1999. The zygotes derives from IVF were cocultured with cumulus cells in YS medium containing 20% hFF for 5days. Two or three of the best balstocysts produced on day 5 were transferred into the uterus, and then supernumerary blastocysts were randomly divided into two groups. One was frozen by slow freezing and the other was frozen by vitrification method. The slow freezing procedure was performed in two steps (5% glycerol and 9% glycerol + 0.2 M sucrose for 10 min, respectively) using programmed freezer ($-2^{\circ}C$/min to $-7^{\circ}C$, manual seeding at $-7^{\circ}C$, $-0.3^{\circ}C$/min to $-38^{\circ}C$ and plunged into $LN_{2}$). The blastocysts frozen by slow freezing were thawed at $36^{\circ}C$ then removed glycerol in 7 steps. The vitrification procedure was performed in three steps (10% glycerol for 5 min, 10% glycerol + 20% ethylene glycol for 5 min, 25% glycerol + 25% ethylene glycol and directly $LN_{2}$ within 1 min). The blastocysts frozen by vitrification were thawed at $20^{\circ}C$ water then removed cryoprotectant in 3 steps. In each group, thawed blastocysts were cocultured with cumulus cells in YS medium containing 20% hFF for 18h and transferred into the uterus. The implantation rate was evaluated per transferred blastocysts and the pregnancy rate was evaluated per transfers. Results: The survival rate of vitrified group (74.5%) was higher than slow freezing group (68.0%), but not significant. When 98 thawed blastocysts of vitrification were transferred in 40 cycles, 19 pregnancies (clinical pregnancy rate; 47.5%) were established. One miscarriage occurred in the eighth week of pregnancy (ongoing pregnancy rate; 45.0%). 7 pregnancies were ongoing, 11 pregnancies went to term, and 16 healthy infants were born. The Implantation rate was 31.6%. These results were higher than those obtained by the slow freezing (clinical pregnancy rate; 40.3%, ongoing pregnancy rate; 32.5% and implantation rate; 25.3%), but not significant. Conclusion: Vitrification is a simple, quick and economical method when compared to slow freezing. It will be chosen as a good method of human embryo freezing in IVF-ET programs.

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Studies of Short-Term Variability of Methane in the Moo-Ahn Observatory Site in Korea (무안지역 메탄가스의 단주기적 농도변화에 대한 평가)

  • Choi, Gyoo-Hoon;Youn, Yong-Hoon;Kim, Chang-Hee;Cho, Young-Min;Kim, Ki-Hyeon
    • Journal of the Korean earth science society
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    • v.22 no.4
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    • pp.327-338
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    • 2001
  • In this study, the short-term variability of methane concentrations were investigated over 24-hr scale. The data obtained form the Moo-Ahn (MAN) station located in the western coastal area of Korea were analyzed from various respects to describe its distribution characteristics over short term scale. The MAN data were compared with those obtained from the two major background observatory sites: Point Barrow (Alaska) and Mauna Loa (Hawaii). The mean concentration of methane for the whole study period, when computed using the daily mean values, was found to be 1898${\pm}$85.3ppb (N=812). The mean values for the two comparable sites were observed to be 1832${\pm}$29.6ppb (N=823) for Point Barrow and 1745${\pm}$14.8ppb (N=818) for Mauna Loa. According to the analysis of frequency distribution. the mode value for the MAN area is found to be 1900ppb, but the mean concentration for Point Barrow and Mauna Loa are shown to have relatively low values of 1850 and 1750ppb, respectively. When examined over diurnal scale, the CH$_4$data for the MAN area exhibit a rather consistent trend; CH$_4$level is low during the daytime (after 6:00 A.M) and rises during the nighttime. The findings of the generally enhanced methane concentration in the MAN station may be explained form various respects. One of the most important reasons is that the MAN area is under the influence of various source processes relative to all the other stations under consideration. The short-term distribution patterns for the MAN station are hence characterized not only by the high methane concentration but also by the high oscillation in its CH$_4$concentration level.

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Fundamental Study for Extension of Application of Recycled Concrete Aggregate: Spun High Strength Concrete (순환골재의 사용성 확대를 위한 연구: 원심력콘크리트로의 적용)

  • Sim, Jong-Sung;Park, Cheol-Woo;Park, Sung-Jae;Kim, Hyun-Jung;Kim, Taeg-Wang;Lee, Man-Suk
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.2 no.1
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    • pp.103-112
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    • 2006
  • Along with recent improvement of recycling technique, the quality of the recycled concrete aggregate have become very competitive to the natural concrete aggregate. Therefore, a practical use of the recycled concrete aggregate may be possible for structural members. Majority studies about the recycled concrete aggregate was emphasized a limitation of fundamental study concerned with a strength characteristics and durability of the recycled aggregate concrete, there is use for the structural members. Therefore, for the extension of application of recycled concrete aggregate, this investigation verifies the strength characteristics recycled concrete aggregate of the spun-concrete products with various coarse and fine recycled aggregate replacement ratio(coarse recycled aggregate: 0%, 20%, 40%, 60%, 100%; fine recycled aggregate: 0%, 30%, 60%, 100%) and with addition of cellulose fibers(0%, 0.01%, 0.03%, 0.05%, 0.08%). From the test results, The strength of spun concrete used with recycled aggregate [NR specimen], was measured as 72MPa, was found to be very approximately to the strength of spun concrete used with the natural aggregate(NN specimen), was measured as 74MPa, when only fine aggregate was replaced with the recycled. Therefore, the fine recycled concrete aggregate can be successfully used in the spun high strength concrete product. The compressive strength of all specimens used the specialty cellulose fiber were measured as about 70M Pa, however, the increasement of the specialty cellulose fiber content is showed to decrease compressive strength of spun concrete. Therefore, it is anticipated that the specialty cellulose fiber can be applied to the various spun concrete products.

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Die Organisation von Mikrostrukturen der zweisprachigen $W\"{o}rterb\"{u}cher$ Deutsch/Koreanisch (독-한 두말사전의 미시구조 조직)

  • Kim Kyong
    • Koreanishche Zeitschrift fur Deutsche Sprachwissenschaft
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    • v.5
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    • pp.183-202
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    • 2002
  • Die vorliegende Arbeit verfolgt zwei Ziele: zum einen sollen die Entwicklungen in der modernen zweisprachigen Lexikographie mit Ausgangssprache Deutsch skizzenhaft vorgestellt und einige Forschungsdefizite benannt werden, zum anderen sollen die Ergebnisse und Methoden der neueren Lexikographie anhand von Beispielartikeln der drei $einschl\"{a}gigen$ deutsch-koreanischen $Gro{\ss}w\"{o}rterblicher$ kontrastiert und diskutiert werden. Zuerst wird eine Typologie der zweisprachigen $W\"{o}rterb\"{u}cher$ erstellt, derzufolge es jeweils 2 aktive und 2 passive Worterblicher pro Sprachenpaar gibt. Das Aktiv-Passiv­Prinzip gilt als ein grundlegender Ausgangspunkt $f\"{u}r$ die zweisprachige Lexikographie. Eine Erweiterung der Unterscheidungskriterien scheint nicht $zweckm\"{a}{\ss}ig$ und angesichts praktischer Schwierigkeiten auch kaum realisierbar. $Pl\"{a}diert\;wird\;f\"{u}r\;eine\;st\"{a}rkere\;Ber\"{u}cksichtigung$ der Benutzungssituationen, zu denen z.B. der Grad der Sprachbeherr­schung der jeweiligen Benutzergruppe, die $m\"{o}glichen\;Benutzungsanl\"{a}sse$, der Kenntnisstand $bez\"{u}glich$ der Benutzerhinweise sowie die technische Geschicklichkeit bei der $W\"{o}rterbuch-benutzung\;etc.\;zu\;z\"{a}hlen$ sind. In makrostruktueller Hinsicht werden die Selektion und die Anordnung der Lemmata diskutiert. Bei der Lemmaauswahl $w\"{a}re\;es\;w\"{u}nschenswert$, auf der Grundlage eines Lemmavergleiches der verschiedensten Quellenworterbucher ein datenbasiertes Korpus zu erstellen. Dazu $k\"{o}nnten$ folgende Materialien ausgewertet werden: (1) einsprachige allgemeine (ad spezielle) $W\"{o}rterb\"{u}cher$ (z.B. Deutsch/Koreanisch), (2) zweisprachige allgemeine (od spezielle) Worterblicher (z.B. Deutsch-Koreanisch, Deutsch-Englisch) etc. Die $blo{\ss}e\;\"{U}bersetzung$ lediglich eines einzigen $Quellenw\"{o}rterbuches\;k\"{o}nnte$ dagegen zu $unerw\"{u}nschten\;Einseitigkeiten\;f\"{u}hren$. Was die Anordnung der Lemmata in zweisprachigen $W\"{o}rterb\"{u}chern$ betrifft, $k\"{o}nnen$ dieselben drei makrostrukturellen Typen unterschieden werden, wie in einsprachigen $W\"{o}rterb\"{u}chern$: (1) glattalphabetisch, (2) nischenalphabetisch, (3) nestalphabetisch. Unter den zu untersuchenden $W\"{o}rterb\"{u}chern$ weisen das EDK und das HDK die nischenalpha­betische Makrostruktur auf, das MDK ist dagegen nestalphabetisch angeordnet. Je nachdem, wie die Polysemiestruktur und die Mehr-Wort-Einheit kombinieren, werden die drei Arten der Mikrostruktur unterschieden: (1) die integrierte Mikrostruktur, (2) die nichtintegrierte Mikrostruktur, (3) die partiell integrierte Mikrostruktur. $W\"{a}hrend$ das EDK und das HDKeine integrierte Mikrostruktur besitzen, weist das HDK eine partiell integrierte Mikrostruktur auf. Die Artikelgestaltung durch die nichtintegrierte Mikrostruktur, die $h\"{a}ufig$ in der zweisprachigen Lexikographie angewandt wird und entsprechende Vorteile besitzt, sallte $k\"{u}nftig\;als\;Gestaltungsm\"{o}glichkeit\;st\"{a}rker$in Betracht gezogen werden. In Bezug auf die Organisation der Mikrostruktur werden vier Bauteile, das sind Lemma-, $\"{A}quivalent-$, Diskriminator- und Beispielangaben untersucht. Die $\"{U}bersetzungs\"{a}quivalente$ werden je nach dem lexikalisch-semantischen Abdeckungsgrad mit dem Lemma in drei Typen eingeteilt: (1) $Voll\"{a}quivalent,\;(2)\;Teil\"{a}quivalent,\;(3)\;Null\"{a}quivalent$. In der Mehrheit kommen die Teil- oder $Null\"{a}quivalente$ vor, weil die ausgangssprachlichen Lemmata und die zielsprachlichen $\"{A}quivalente$ in sich Polysemiestruktur aufweisen. $Informationsm\"{a}ngel$ auszugleichen ist die Funktion des Diskriminators, in dem Glosse, Markierungen und metasprachliche $Erl\"{a}uterungen$ zusammenwirken. $Verbesserungsw\"{u}rdig\;sind\;die\;g\"{a}ngigen$ deutsch-koreanischen $W\"{o}rterb\"{u}cher$ var allem im Hinblick auf die stilistischen Markierungen; die Inkongruenz des Stils zwischen den beiden verschiedenen Sprachen wird bislang zu wenig $ber\"{u}cksichtigt$ und sagar in ein und demselben $W\"{o}rterbuch$ nicht konsequent dargestellt. Trotz der relativen $Geringsch\"{a}tzung$ von Beispielangaben in der $europ\"{a}ischen$ zweisprachigen passiven Lexikographie sallte diesen in deutsch-koreanischen $W\"{o}rterb\"{u}chern$ mehr Aufmerksamkeit gewidrnet werden. Sie sind dem koreanischen Benutzer eine wichtige Hilfe, indem sie die $\"{A}quivalentenangaben\;implizite\;erg\"{a}nzen$ und Informationen $\"{u}ber$ die syntaktisch-semantische und pragmatische Kontextrestriktion bieten. $Dar\"{u}berhinaus$ stellen sie selbst interessante kulturelle, geistige und landeskundliche etc. Informationen dar. Was den Artikelaufbau betrifft, wird das Van Dale-Modell diskutiert, d.h. das kategoriell-semantisch-alphabetische Prinzip, das trotz mancher Kritikpunkte viele interessante Anregungen $f\"{u}r$ die zweisprachige Lexikographie Deutsch-Koreanisch bietet, wo z.B. noch nicht die $Pr\"{a}positionen$ in der Beispielangabe durch typographische Hervorhebung $pr\"{a}sentiert$ worden sind. Aus $Platzgr\"{u}nden$ sind hier nur wenige Beispielartikel mit substantivischen Lemmata $angef\"{u}hrt$ und analysiert worden. Um die $h\"{o}here$ Generalisierbarkeit zu erreichen, brauchen die Untersuchungs- materialien mindestens einen bestimmten Umfang. Derartige empirische Forschungen $k\"{o}nnen$ als Impulse dazu beitragen, $k\"{u}nftige\;W\"{o}rterb\"{u}cher$ im Sinne einer $Ber\"{u}cksichtigung$ neuerer lexikographischer Erkenntnisse verbessern zu helfen.

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The Effect of Au Addition on the Hardening Mechanism in Ag-20wt% Pd-20wt% Cu (Ag-20wt% Pd-20wt% Cu 3원합금(元合金) 및 Au첨가합금(添加合金)의 시효경화특성(時效硬化特性))

  • Park, M.H.;Bae, B.J.;Lee, H.S.;Lee, K.D.
    • Journal of Technologic Dentistry
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    • v.19 no.1
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    • pp.21-35
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    • 1997
  • The Ag-Pd-Cu alloys containing a small amount of Au is commonly used for dental purposes, because this alloy is cheaper than Au-base alloys for clinical use. However, the most important characteristic of this alloy is age-hardenability, which is not exhibited by other Ag-base dental alloys. The specimens used were Ag-20Pd-20Cu ternary alloy and Au addition alloy. These alloys were melted and casted by induction electic furace and centrifugal casting machine in Ar atmoshpere. These specimens were solution treated for 2hr at $800^{\circ}C$ and were then quenched into iced water, and aged at $350{\sim}550^{\circ}C$ Age-hardening characteristics of the small Au-containing Ag-pPd-Cu dental alloys were investigated by means of hardness testing, X-ray diffraction and electron microscope observations, electrical resistance, differential scanning calorimetric, emergy dispersed spectra and electron probe microanalysis. Principal results are as follows : Hardening occured in two stages, I. e., stage I in low temperature and stage II in high temperature regions, during continuous aging. The case of hardening in stage I was due to the formation of the Llo type face centered tetragonal PdCu-ordered phase in the grain interior and hardening in stage I was affedted by the Cu concentration. In stage II, decomposition of the $\alpha$ solid solution to a PdCu ordered phase(L1o type) and an Agrich ${\alpha}2$ phase occurred and a discontiunous precipitation occurred at the grain boundary. Form the electron microscope study, it was concluded that the cause of age-hardening in this alloy is the precipitation of the PdCu ordered phase, which has AuCu I type face-centered tetragonal structure. Precipitation procedure was ${\alpha}\to{\alpha}+{\alpha}2+PdCu\to{\alpha}1+{\alpha}2+PdCu$ at Pd/Cu = 1 Ag-Pd-Cu alloy is more effective dental alloy as ageing treatment and is suitable to isothermal ageing at $450^{\circ}C$.

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