• Journal of Sensor Science and Technology
• /
• v.17 no.2
• /
• pp.127-132
• /
• 2008

The effect of $CeO_2$ as a sintering additive on the microstructure and the piezoelectric property of yPb$(Sb_{0.5}Nb_{0.5})O_3$-(1-y)Pb$(Zr_{0.52}Ti_{0.48})O_3$ ($0{\leq}y{\leq}0.1$, PSN-PZT) for a hypersonic sound speaker (HSS) application was investigated. The samples were sintered at $1250^{\circ}C$ for 2 h. The crystal structure and surface morphology of the samples were examined using XRD and FE-SEM, respectively. Study on the influence of $CeO_2$ additives on the dielectric and piezoelectric properties indicated that the $CeO_2$-added PSN-PZT system had a high piezoelectric properties. The optimized results of ${\varepsilon}_r=1209$, $K_p$=52% $d_{33}$=351(pC/N) and $Q_m$=1230.16 were obtained at 0.4 wt.% $CeO_2$-added PSN-PZT.

• Journal of the Korean Solar Energy Society
• /
• v.23 no.1
• /
• pp.1-8
• /
• 2003

Various efforts to combine new high-tech materials with solar system have been progressed nowadays in order to improve the performance of the existing passive solar system. TIM(Transparent Insulation Material) replacing the conventional outer building envelope glazing as well as the wall is good example for this trend. TI integrated wall is a thermal mass wall with a special shaped TIM instead of using typical envelope materials The tested TIM type is a small(diameter 4mm and thickness 50mm) capillary tube of Okalux model and cement brick(density 1500kg/m3). The purpose of this study was to analyze the thermal performance through the actual measurements performed in a test cell. This study was carried out to justify the following issues. 1) the impact of Tl-wall over the temperature variations 2) the impact of mass wall surface absorptance over the transient thermal behavior and 3) the impact of thermal mass wall thickness over the temperature variations. Finally, as results indicated that the peak time of room temperature was shifted about one hour early when absorptance of thermal mass wall changed from 60% to 95% for the 190mm thickness thermal mass wall test case. the temperature difference of both surfaces of thermal mass wall surface showed about $23^{\circ}C$ during a day of March for the 380mm thickness thermal mass wall case. However, the thermal mass wall was over-heated by outside temperature and solar radiation in a day of May the temperature difference of both surfaces of thermal mass wall surface was indicated $10^{\circ}C$ and inside temperature was observed more than average 22C.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.27 no.10
• /
• pp.1630-1635
• /
• 2003

The deformation and fracture behaviors of a bulk amorphous metal, Zr-based one (Zr$\_$41.2/Ti$\_$13.8/Cu$\_$12.5/Ni$\_$10/Be$\_$22.5/: Vitreloy), were investigated over a strain rate range (7x10$\^$-4/～4 s$\^$-1/). The uniaxial compression test and the indentation test using 3mm-diameter WC balls were carried out under quasi-static loading conditions. As a result, at the uniaxial compressive state, the fracture stress of the material was very high (～1,700MPa) and the elastic strain limit was about 2%. The fracture strength showed a strain rate independent behavior up to 4 s$\^$-1/. Using indentation tests, the plastic deformation behavior of the Zr-based BAM up to a large strain value of 15% could be achieved, even though it was the deformation under locally constrained condition. The Meyer hardness of the Zr-based BAM measured by static indentation tests was about 5 GPa and it revealed negligible strain hardening behavior. At indented sites, the plastic indentation occurred forming a crater and well-developed multiple shear bands were generated around it along the direction of 45 degree when the indentation load exceeded 7kN. With increasing indentation load, shear bands became dense. The fracture surface of the specimen after uniaxial compressive tests showed vein-like pattern, typical morphology of many BAMs.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.29 no.5
• /
• pp.268-273
• /
• 2016

In this study, we observed current-voltage characteristics of the MIM (metal-insulator-metal) structure. The $WO_x$ material was used between metal electrodes as the oxide insulator. The structure of the $Al/WO_x/TiN$ shows bipolar resistive switching and the operating direction of the resistive switching is clockwise, which means set at negative voltage and reset at positive voltage. The set process from HRS (high resistance state) to LRS (low resistance state) occurred at -2.6V. The reset process from LRS to HRS occurred at 2.78V. The on/off current ratio was about 10 and resistive switching was performed for 5 cycles in the endurance characteristics. With consecutive switching cycles, the stable $V_{set}$ and $V_{reset}$ were observed. The electrical transport mechanism of the device was based on the migration of oxygen ions and the current-voltage curve is following (Ohm's Law ${\rightarrow}$ Trap-Controlled Space Charge Limited Current ${\rightarrow}$ Ohm's Law) process in the positive voltage region.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.353-353
• /
• 2014

본 연구에서는 Sputter를 이용하여 Room Temp.에서 증착된 NbOx 박막의 열처리에 따른 결정도를 분석하고, 이러한 결정도의 변화가 Metal Insulator Transition특성에 의한 Threshold switching에 어떠한 영향을 미치는 지에 대하여 연구하였다. NbOx 박막의 threshold switching 특성 분석을 위해, 1.4um의 TiN 위에 15nm의 NbOx를 증착하고 Top Electrode로 Pt를 증착하여 측정하였다. 증착된 NbOx는 Nb metal target으로 Reactive Sputter를 이용하여 Room Temp.에서 증착하였으며, 조성은 Partial Oxygen Pressure를 이용하여 조절하였다. 증착된 박막의 결정도는 TEM 및 XRD를 통하여 분석하였고 조성은 XPS를 이용하여 분석하였다. Sputter로 NbOx 증착 시 Partial Oxygen Pressure에 따른 조성을 XPS로 확인한 결과, Partial Oxygen Pressure 2%에서 NbOx의 조성을, 5%이상일 경우, Nb2O5의 조성을 가지는 것으로 확인되었다. Partial Oxygen Pressure 2%에서 증착한 NbOx 박막의 열처리에 따른 결정도를 분석한 결과, As-Dep상태에서는 amorphous상태였다가 600'C이상으로 1분간 열처리를 하였을 때 NbOx의 결정도가 증가함을 확인하였다. I-V 특성 측정 결과, 열처리 온도가 증가함에 따라 initial current가 점진적으로 증가하는 경향을 보이는데, 이는 열처리 시 amorphous상에서 poly-crystalline으로 미세구조의 변화가 일어나면서 grain boundary가 생성되며 생성된 grain boundary를 통해 leakage current가 증가하는 것으로 추측된다. 또한, 결정도가 증가함에 따라 electro-forming voltage가 감소하는 경향을 보이며 안정된 threshold switching 특성을 보이고 있다. 특히, 700'C 1분간 열처리 시에는 electro-forming 과정이 없이 threshold switching이 나타나는 현상이 관찰되었다. 이로 미루어 보아, threshold switching에서 나타나는 forming 현상은 local joule heating에 의해 박막이 결정화 되는 과정으로 추측된다. 결론적으로, 박막의 결정도가 initial current 및 Threshold switching 특성에 큰 영향을 미치는 것으로 예상된다.

• The Bulletin of The Korean Astronomical Society
• /
• v.36 no.1
• /
• pp.27.1-27.1
• /
• 2011

We obtained the spectra of 93 Planet host stars and 73 normal field stars in F, G, K type using BOES at BOAO. We measured the equivalent width of Fe and 25 elements lines using the automatic EW measurement program, TAME(Tools for Automatic Measurement of Equivalent-widths) and estimated the elemental abundances by synth and abfind driver of MOOG code. Since the absence of planets in the normal field stars cannot be "completely" proved, this work focused on the chemical abundances and planet properties of planet host stars, which have the massive planets close to the parent star relatively. We carried out an investigation for the difference of abundances between stars with "Hot Jupiter" and normal field stars with no known planets. We examined the chemical composition of 25 elements, such as C, N, O, S, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Sr, Y, Zr, Ba, Ce, Nd, and Eu by EW measurements, and the S abundances were estimated using synthetic spectrum. We have found that [Mg/Fe] and [Al/Fe] for planet host stars have lower limit comparing with those of comparison stars, and [Ca/Fe] of host star with Neptunian planets is relatively lower than the other host stars with massive planets. We have performed the Kolmogorov-Smirnov test, and examined the ratio of planet host stars to all stars for each bin of [X/H]. As a result, we noted that the O, Si, and Ca abfor undances are strongly related with the presence of planets.

• Economic and Environmental Geology
• /
• v.43 no.3
• /
• pp.269-278
• /
• 2010

We investigated characteristics of the coloring material of Dancheong pigments and hope that this study contributes the revival of traditional Dancheong pigments color. For this purpose, we collected Dancheong fragment samples that fell off naturally from old wooden buildings in Gwangju and Jeonnam and analyzed the natural coloring material by XRD and EDS-SEM analysis method. In white pigments of Dancheong fragments, it is confirmed that gypsum$(CaSO_{4}{\cdot}2H_{2}O)$, quartz$(SiO_{2})$, white lead$(PbCO_{3})$ and calcite$(CaCO_{3})$ which have been used for white pigments since ancient times and $TiO_{2}$ which is common used in modern times. In red pigments of Dancheong fragments, it is confirmed that hematite$(Fe_{2}O_{3})$ and red lead$(Pb_{3}O_{4})$, which have been used for red pigments since ancient times and C.I. pigment orange $13(C_{32}H_{24}C_{12}N_{8}O_{2})$ but there is no cinnabar(HgS) which has been used since B.C. 3000 in China. In yellow pigments of Dancheong fragments, it is confirmed that crocoite$(PbCrO_{4})$ and massicot(PbO). In blue pigments of Dancheong fragments, it is confirmed that sodalite$(Na_{4}BeAlSi_{4}O_{12}Cl)$ and nosean $(Na_{8}Al_{6}Si_{6}O_{24}SO_{4})$ as coloring material of blue pigment and C.I. pigments blue $29(Na_{7}Al_{6}Si_{6}O_{24}S_{3})$ which is used in modern times. In green pigments of Dancheong fragments, it is confirmed that calumetite$(Cu(OHCI)_{2}{\cdot}2H_{2}O)$, escolaite(Cr2O3), dichromium trioxide$(Cr_{2}O_{3})$, emerald green$(C_{2}H_{3}As_{3}Cu_{2}O_{8})$, and C.I. pigments green$(C_{32}H_{16}-XCl_{x}Cu_{8})$ which is used in modern time. In black pigments of Dancheong fragments, Chiness ink(carbon black) is confirmed.

• Journal of the Korean Society for information Management
• /
• v.5 no.1
• /
• pp.53-78
• /
• 1988

The purpose of this study is to verify the factors determining core journals in a field based upon the results of the citation analysis of the journals in the field of Korean History(KH). In order to verify the determinant factors, dividing the articles of the KH journals into their novelty and author's seniority, the following hypotheses were established. Hypothesis 1: When a KH journal publishes more articles on prehistoric and ancient eras than others, the journal will have higher chance to be included in the core journals. Hypothesis 2: When a KH journal publishes more articles by senior researchers than others, the journal will have higher chance to be included in the core journals. To achieve the purpose, the cited articles found in the two sample journals, namely, Backsan Hakbo and Hanguksa Yongu were analysed during the past 20 years from 1962 to 1981. Applying the Hirst's Discipline Impact Factor method to the the study, Historical Science Impact Factor(HSIF) on the samples itself and the historical era dealt with in the articles and the seniority of the authors during every five-year period. Based upon thr present study to ver~fy the two hypotheses, the following conclusions have been reached. 1) Tht. most influencing sublect mattcr era or1 thix liSIF of the lo~lrual is arranged in prehistoric arid ancient, Koryo, Chosun, recent era, and the others by order of era. 2 ) Clial~g~~lg a fringe or semicore journal u~to a core j ~ u r n a l , very IISIF' 011 it> article e r a 1s grown up arrd prcllistoric a ~ ~ d ancierlt era:. are, s p c c ~ a l l ~ , incr.eased high relatively. Char~ging a core journal int:~ a fr~ngr or semicort. journal, t.very IISIF ti dropped and prel~istc~ric and ancieut taras arc, fallen sharp relatively. 3) The most irlflr~encin~ s~niority 011 the t1SII- of ihc journal I. the senior.., written or1 prehistoric and ancient eras. Above all, the senilir'b HSIF olr prehistoric anti anclent e r a s a r e most ~nfluencing the cliangi~rg of the core journal into the fringe ur bemicore. .i) flypothesis fl is no1 vcrif~ed i r t general. T l ~ e rt, lative connections bet wee^^ the senior's HSIF 011 each era and tht, ~ l ~ a l ~ g i t l g of the tort. ji1ur.tia1 arc \:er~fied in part hut r~ot in the wliole. 5) 'The reason why the 11SIF or1 prehistori~. arid ar~cic~nt e r a s is higl~er than others can be assumed becaltic the new <, xcavations a r r contit~ued actively i l l the prrsr.llt as to the relics arid remains or1 that eras. Accordingly, the HSIF' r i l l thr 11ew 3ubject matter l~ke arcl~acmlogy trends to grow up greatly. Bctween the senior's and juriior's JISIE', junior'.; is higl~er than s., nior's except ancient e r a . That reason can be assumed bccausr Iunlorb t r j to solve the ex~sting problems thr~urglr their ow11 new viewpoints and sights. So, i t should be studied whether the 11SlF on the artic1t.s of the new subject matters and viewpoirrts is influenced to the changing of the core jorlrnal or not.

• Journal of the Speleological Society of Korea
• /
• no.74
• /
• pp.23-31
• /
• 2006

(1) Kaeusetgul Cave in Kimnyong-Ri, Jeju-Do, Korea. Kaeuset-gul Cave (KC) is situated in NNE area of the Manjang-gul cave (125m a.s.l.). Kaeuset-gul Cave lies at $126^{\circ}45'22"$ E in longitude and $33^{\circ}33'09"$ N in latitude. The coast belong Kimnyeong-Ri, Kujwa-eup, Jeju-Do. Altitude of the cave-entrance is 10m and length of the cave is 90m. Lava hand-specimens of KC are studied by X-ray fluorescence analysis (XRF). Average major chemical components of specimens from KC is as follows (wt.%); $SiO_2=47.03$, $TiO_2=3.16$, $Al_2O_3=18.41$, FeO*=13.53, MnO=0.14, MgO=5.05, CaO=8.66, $Na_2O=2.81$, $K_2O=0.67$, $P_2O_5=0.55$ in KC. Polarizing microscopic studyindicates that these specimens are described of alkali-basalt. (2) Tachibori Fuketsu (Cave) in Shizuoka Prefecture, Fuji Volcano, Japan Tachibori Fuketsu lies attoward the south in skirt of the Fuji volcano, $138^{\circ}42'04"$ east longitude and $35^{\circ}18'00"$ north latitude. The location of cave entrance is 2745, Awakura, Fujinomiya-shi, Shizuoka Prefecture. The above sea level and length of Tachibori Fuketsu are 1,170m and 82m. Average major chemical components of specimens from cave areas follows (Total 100 wt.%) ; ($SiO_2$=50.52, $TiO_2$=1.69, $Al_2O_3$=15.47, FeO*=13.13, MnO=0.20, MgO=5.97, CaO=9.17, $Na_2O$=2.52, $K_2O$=0.94 and $P_2O_5=0.40).$ Polarizing microscopic study indicates that these specimens may belong to tholeiite-basalt series. According to polarizing microscopic study, Au (Augite), P1 (Plagioclase), and O1 (Olivine) are contained as phenocryst minerals. (3) Gorely Cave in Kamchatka Peninsula, Russia Gorely caldera is located at the southeastern part of Kamchatka Peninsula, about 75km southwest of Petropavlovsk-Kamchatskiy.. Gorely lava caves are situated in NHE area of Mt. Gorely volcano (1829m a.s.1.). One of lava cave (Go-9612=K-1) lies at $158^{\circ}00'22"$ east longitude and $52^{\circ}36'18"$ north latitude. The elevation of cave entrance is about 990m a.s.1. and the main cave extends in the NNW direction for about 50m by 15m wide and 5m in depth. The cave of K-3is near the K-1 cave. "@Lava hand-specimens K-1 and K-3 caves are studied by X-ray fluorescence analysis and polarizing microscopic observation. Average major chemical components of specimens from these caves are as follows (wt.%) ;($SiO_2$=55.12, $TiO_2$=1.25, $Al_2O_3$=16.07, T-FeO* =9.41, MnO=0.16, MgO=5.01, CaO=7.21, $Na_2O$=3.39, $K_2O$=1.92, $P_2O_5$=0.45) and these values indicate that the Gorely basaltic andesite belong to high alumina basalt. Polarizing microscopic study indicates that these specimens are described of Augite andesite.

• Korean Journal of Poultry Science
• /
• v.31 no.3
• /
• pp.165-170
• /
• 2004

The objective of this study was to evaluate the carcass and meat quality of broiler chicken when slaughtered after treating with different source of grain(T1, 100% corn; T2, 50% corn + 50% brown rice; T3, 100% brown rice) in broiler diet. The carcass weight was decreased when feeding level of rice increased. The yield of breast was higher in T2(18.6%) than T1(17.3%) and T3(l7.9%). The L values(L *) and b values(b*) in meat color were decreased as the feeding level of rice increased when compared to T1(P < 0.05). Warner-Bratzler shear force(WBS) values were higher in T2 and T3 compared to T1. Cooking loss(%) was increased for T2(23.49%) and T3(24.50%) compared to T1(22.90%). In fatty acid composition, linoleic acid(C18:2, n6) contents were significantly lower in T2(31.89%) and T3(27.89%) when compared to TI(33.21%)(P < 0.05), and the total contents of unsaturated fatty acids(UFA) were 76.85%(T1), 77.22%(T2), or 75.49%(T3). The ratio of n6/n3 was decreased as the level of rice increased in the feed(T1 19.89%, T2 17.73%, and T3 17.01%). In conclusion, the meat quality was not significantly different between T1 and T2 from the results of carcass weight, meat color, WBS, and fatty acid composition; therefore, brown rice can be substituted for 50% of corn in the broiler diets.