• Title/Summary/Keyword: nCalc

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Assessing the long-term durability and degradation of rocks under freezing-thawing cycles

  • Seyed Zanyar Seyed Mousavi;Mohammad Rezaei
    • Geomechanics and Engineering
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    • v.34 no.1
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    • pp.51-67
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    • 2023
  • In this research, the degradation rate of physical properties of the Angouran pit bedrock (calc-schist) is first investigated under the specific numbers of freeze-thaw (F-T) cycles. Then, the durability of calc-schist specimens against the F-T cycle number (N) is examined considering the mechanical parameters, and using the decay function and half-time techniques. For this purpose, point load strength (IS(50)), second durability index (Id2), Brazilian tensile strength (BTS), and compressive (VP) and shear (VS) wave velocities of calc-schist specimens are measured after 0, 7, 15, 40, and 75 N. For comparing the degradation rate of mechanical properties of available rock types on the Angouran mine walls, these tests are also carried out on the limestone and amphibolite schist specimens beside the calc-schist. According to test results, the exponential regression models are developed between the mechanical parameters of rock specimen's and N variable. Also, the long-term durability of each rock type versus N is studied using the decay function and half-time techniques. Results indicated that the degradation rate differs for the above rock types in which amphibolite schist and calc-schist specimens have the highest and least resistance against the N, respectively. The obtained results from this study can play a key role in the optimal design of the mine's final walls.

Geochemical Study of the Cretaceous Granitic Rocks in Yeosu Area (여수 지역에 분포하는 백악기 화강암류에 대한 지화학적 연구)

  • Wee, Soo-Meen;Kim, Eun-Hyo
    • Journal of the Korean earth science society
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    • v.30 no.3
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    • pp.267-281
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    • 2009
  • Cretaceous intrusive and extrusive rocks are widely distributed in the southern part of the Korean peninsula, possibly the result of intensive magmatism which occurred in response to subduction of the Pacific plate beneath the northeastern part of the Eurasian plate. Geochemical and petrological study on the Cretaceous granitic rocks of the Yeosu area were carried out in order to constrain the petrogenesis of the granitic rocks and to establish the paleotectonic environment of the southwestern part of the Korean peninsula. Igneous rocks of the Yeosu area consist of diorite, hornblende biotite pite and micrographic granite. Chondrite normalized REE patterns show generally enriched in LREE ($(La/Lu)^{cN}$=4.2-13.3). Diorites show flat to slight negative Eu anomalies while micrographic granites have strong negative Eu anomalies. The ${\Sigma}REE$ of the granites are 76.2-235 ppm, which corresponds to the range of the continental margin granite. Whole rock chemical data of the granitic rocks from the Yeosu area indicate that the rocks have characteristics of calc-alkaline series in the subalkaline field. On the A/NK vs. A/CNK and tectonic discrimination diagrams, parental magma type of the granites corresponds to I-type and volcanic arc granite (VAG). Interpretations of the chemical characteristics of the granitic rocks favor their emplacement in a compressional tectonic regime at continental margin during the subduction of Pacific plate.

A Study on a Roughness Coefficient in Korea River using Hydraulic Models (수리학적 모형을 이용한 국내하천의 조도계수 산정 연구)

  • Kim, Joo-Young;Lee, Jin-Woo;Lee, Jong-Kyu;Cho, Yong-Sik
    • 한국방재학회:학술대회논문집
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    • 2010.02a
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    • pp.96.1-96.1
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    • 2010
  • 하천의 설계홍수위를 결정할 때 가장 중요한 변수중의 하나는 우리가 흔히 부르는 Manning의 조도계수 n으로 과거 수십 년 동안 국내 외에서 많은 연구가 진행되어 왔고 현재에도 끊임없이 여러 연구자들의 관심의 대상이 되고 있다. 이러한 조도계수는 보통 부등류 모형에 의한 방법, NCALC 모형에 의한 방법, 하상재료 또는 사진 index를 통한 방법을 사용하고 있지만 일관성이 떨어질 뿐만 아니라 산정된 조도계수가 유량 또는 수위에 관계없이 일정한 조도계수 만을 제시하고 있다는 문제점을 가지고 있다. 이러한 문제점 등을 해결하고자 부정류 수치모형을 이용하여 하천 구간에서의 조도계수를 유량의 함수로 산정하는 연구가 활발히 진행되어 왔다. 본 연구에서는 이러한 조도계수의 여러 특성을 파악하고자 국내 주요 하천인 한강, 낙동강, 금강의 본류 및 지류에 대해서 수위관측소를 기준으로 구간을 구분하고 과거 주요 홍수 수문곡선을 선정하고 부정류 해석을 통하여 다양한 유량에 대한 하천 구간별 조도계수를 산정하였다.

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Synthesis, Characterization, and Catalytic Properties of Gp 6 Metal Complexes of 1-N,N-dimethylaminomethyl-$1^{\prime}$,2-bis(diphenylphosphino)ferrocene (FcNPP). X-ray Crystal Structure of W$(CO)_4({\eta}^2-FcNPP(O)-P,N)$

  • Kim, Tae-Jeong;Kim, Yong-Hoon;Kim, Eun-Jin;Oh, Sang-Ho;Kim, Hong-Seok;Jeong, Jong-Hwa
    • Bulletin of the Korean Chemical Society
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    • v.15 no.5
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    • pp.379-386
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    • 1994
  • Reactions of 1',2-bis(diphenylphosphino)-l-(N,N-dimethylaminomethyl)ferrocene (FcNPP) with $M(CO)_6$ (M=Cr, Mo, W) in the presence of TMNO (Trimethylamine oxide) in a stoichiometric ratio of 1 : 1.5 : 3.5 produced a series of Gp 6 metal carbonyl derivatives with a variety of coordination modes: M(CO)$_4({\eta}^2$-FcNPP-P,P) (M=Cr, Mo, W), $M(CO)_5({\eta}^1-FcNPP-P) (M=Mo, W)\;,\; M_2(CO)_9({\eta}^1\;,\;{\eta}^2-FcNPP-P,P,N) (M=Cr, Mo)\;,\;M_2(CO)_{10}({\eta}^1\;,\;{\eta}^1-FcNPP-P,P) (M=Cr, Mo, W)\;, and\;W(CO)_4({\eta}^2-FcNPP(O)-P,N)$. All these complexes were characterized by microanalytical and spectroscopic techniques. In one case, the structure of W(CO)$_4({\eta}^2$-FcNPP(O)-P,N) was determined by X-ray crystallography. Crystals are monocinic, space group P$2_{1/C}$, with a=10.147(2), b=19.902(3), c=19.821(4) ${\AA},\;{\beta}=96.88(2)^{\circ},\;V=3974(l){\AA}^3$, Z=4, and $D_{calc}=1.64 g cm^{-3}$. The geometry around the central tungsten metal is a distorted octahedron, with the nitrogen and phosphorus atoms being cis to each other. Some of these complexes exhibited catalytic activities in the allylic oxidation and epoxidation of cholesterly acetate. Other oxidation products were also formed with the different chemical yields and product distribution depending upon the ligand and the central metal.

A Study on a Roughness Coefficient of Representative River in Korea (국내 대표하천의 조도계수 산정 연구)

  • Park, Hyun-Jin;Ha, Tae-Min;Lee, Jong-Kyu;Cho, Yong-Sik
    • 한국방재학회:학술대회논문집
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    • 2010.02a
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    • pp.95.2-95.2
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    • 2010
  • 조도계수는 자연하천의 흐름해석에 사용되는 매우 중요한 변수로서, 하천의 단면, 하상입자들의 크기 및 형상, 식생, 수로단면의 변화, 수로의 만곡, 수위와 유량 등 매우 복합적인 요소의 영향을 받는 경험적 매개변수이다. 일반 자연하천에서는 유량이 적어질 경우 하천구간 내 여울이나 보의 영향으로 수면 불연속 흐름이 발생할 가능성이 커지기 때문에 수리학적 모형을 이용하여 조도계수를 산정할 경우 계산 구간 내 수면 불연속 구간에서 부정확한 조도계수가 산정되는 한계가 있다. 따라서 본 연구에서는 여울이나 장애물이 존재하지 않는 대표하천을 선정하여 대표적인 특성을 갖는 하천에 대하여 평 갈수기 조도계수를 산정하였다.

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Studies on the Geology and Geochemistry in the Beonam Mine, Korea (전북 번암광산의 지질과 지화학적 연구)

  • Chung, Jae-Il;Na, Choon-Ki;Lee, Young-Up;Jeon, Seo-Ryeong;Kim, Seon-Young
    • Economic and Environmental Geology
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    • v.28 no.6
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    • pp.623-633
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    • 1995
  • The Beonam deposits which is located in south-western part of Sobaeksan massif are emplaced along $N20{\sim}30^{\circ}E$ trending fissures in Precambrian Sobaeksan gneiss complex. Surrounding granites are inferred to be differentiated and formed from calc-alkaline magma which was generated from remelting or partial melting of the crustral material having igneous composition. The Sr isotope data of ore minerals showing significantly low initial Sr value relative to those of surrounding granite batholiths suggest that the ore-bearing fluid formed the Beonam Au-Ag mine are isotopically distinct from those of the wall rocks, and it indicates that there is no evidence of genetic relationship between ore-bearing fluids and surrounding granites, although further study should be needed. The results of paragenetic studies suggest three stages of hydrothermal mineralization; stage I: base-metal sulfides stage, stage II: late base-metal sulfides, electrum and silver-bearing sulfosalts stage, stage III: minor silverbearing minerals, barren quartz and carbonates stage. The temperature, salinity and pressure of the Beonam deposits estimated from mineral assemblage, chemical composition, fluid inclusion and sulfur isotope geothermometry are as follows; stage I: $200{\sim}315^{\circ}C$, 3.5~6.5 NaCl eq. wt%, 0.28~0.61 Kbar, stage II: $150{\sim}235^{\circ}C$, 4.5~7.4 NaCl eq. wt%, 0.11~0.15 Kbar. The estimated oxygen and sulfur fugacity during first stage mineralization, based on phase relation of associated minerals, range from $10^{35.1}{\sim}10^{-39.7}$ atm. and $10^{-11.0}{\sim}10^{-13.4}$ atm., respectively. All these evidences suggest that the Beonam deposits are polymetallic meso-epithermal ore deposits.

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Product-Rate Correlations for Solvolyses of 2,4-Dimethoxybenzenesulfonyl Chloride

  • Kim, Soo Ryeon;Choi, Hojune;Park, Jong Keun;Koo, In Sun;Koh, Han Joong
    • Bulletin of the Korean Chemical Society
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    • v.35 no.1
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    • pp.51-56
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    • 2014
  • The solvolysis rate constants of 2,4-dimethoxybenzenesulfonyl chloride (1) in 30 different solvents are well correlated with the extended Grunwald-Winstein equation, using the $N_T$ solvent nucleophilicity scale and $Y_{Cl}$ solvent ionizing scale, with sensitivity values of $0.93{\pm}0.14$ and $0.65{\pm}0.06$ for l and m, respectively. These l and m values can be considered to support a $S_N2$ reaction pathway. The activation enthalpies (${\Delta}H^{\neq}$) were 12.4 to $14.6kcal{\cdot}mol^{-1}$ and the activation entropies (${\Delta}S^{\neq}$) were -15.5 to -$32.3kcal{\cdot}mol^{-1}{\cdot}K^{-1}$, which is consistent with the proposed bimolecular reaction mechanism. The solvent kinetic isotope effects (SKIE) were 1.74 to 1.86, which is also in accord with the $S_N2$ mechanism and was possibly assisted using a general-base catalysis. The values of product selectivity (S) for solvolyses of 1 in alcohol/water mixtures was 0.57 to 6.5, which is also consistent with the proposed bimolecular reaction mechanism. Third-order rate constants, $k_{ww}$ and $k_{aa}$, were calculated from the rate constants ($k_{obs}$), together with $k_{aw}$ and $k_{wa}$ calculated from the intercept and slope of the plot of 1/S vs. [water]/[alcohol]. The calculated rate constants, $k_{calc}$ ($k_{ww}$, $k_{aw}$, $k_{wa}$ and $k_{aa}$), are in satisfactory agreement with the experimental values, supporting the stoichiometric solvation effect analysis.

Petrochemical Study on the Cretaceous Volcanic Rocks in Kageo island, Korea (가거도(소흑산도)의 백악기 화산암류에 대한 암석화학적 연구)

  • 김진섭;백맹언;성종규
    • The Journal of the Petrological Society of Korea
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    • v.6 no.1
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    • pp.19-33
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    • 1997
  • This study reports the results about the petrography and geochemical characteristics of 10 representative volacanic rocks. The Cretaceous volcanic rocks distributed in the vicinity of the Kageo island composed of andesitic rocks, dacitic welded tuff, and rhyolitic rocks in ascending order. Sedimentary rock is the basement in the study area covered with volcanic rocks. Andesitic rocks composed of pyroclastic volcanic breccia, lithic lapilli tuff and cryptocrystallin lava-flow. Most dacitic rocks are lapilli ash-flow welded tuff. Rhyolitic rocks consists of rhyolite tuff and rhyolite lava flow. Rhyolite tuff are lithic crystal ash-flow tuff and crystal vitric ash-flow tuff with somewhat accidental fragments of andesitic rocks, but dacitic rocks. The variation of major and trace element of the volcanic rocks show that contents of $Al_2O_3$, FeO, CaO, MgO, $TiO_2$ decrease with increasing of $SiO_2$. On the basis of Variation diagrams such as $Al_2O_3$ vs. CaO, Th/Yb vs. Ta/Yb, and $Ce_N/YB_N$ vs. $Ce_N$, these rocks represent mainly differentiation trend of calc-alkaline rock series. On the discriminant diagrams such as Ba/La and La/Th ratio, Rb vs. Y + Nb, the volcanic rocks in study area belongs to high-K Orogenic suites, with abundances of trace element and ternary diagram of K, Na, Ca. According to the tectonic discriminant diagram by Wood, these rocks falls into the diestructructive continental margin. K-Ar ages of whole rocks are from andesite to rhyolite $97.0{\pm}6.8~94.5{\pm}6.6,\68.9{\pm}4.8,\61.5{\pm}4.9~60.7{\pm}4.2$ Ma, repectively. Volcanic rocks in study area show well correlation to the Yucheon Group in terms of rock age dating and geochemcial data, and derived from andesitic calc-alkaline magma that undergone low pressure fractional crystallization dominated plagioclase at <30km.

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A model for Phase Transformation of Microalloyed Low Carbon Steel Combined with Nb Precipitation Kinetics (Nb 석출 거동을 고려한 저탄소강의 상변태 모델)

  • Kim, D.W.;Cho, H.H.;Park, S.;Kim, S.H.;Kim, M.J.;Lee, K.;Han, H.N.
    • Transactions of Materials Processing
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    • v.26 no.1
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    • pp.48-54
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    • 2017
  • The dissolution and precipitation of Nb, which has been known as strong carbide-forming element, play a key role in controlling phase transformation kinetics of microalloyed steels. In this study, we analyzed both numerically and experimentally the precipitation behavior of Nb-microalloyed steel and its effect on the austenite decomposition during cooling. Nb precipitation in austenite matrix could be predicted by the thermo-kinetic software MatCalc, in which interfacial energy between precipitate and matrix is calculated. The simulated precipitation kinetics fairly well agrees with the experimental observations by TEM. Austenite decomposition, which is strongly affected by Nb precipitation during cooling, was measured by dilatometry and was modeled on the basis of a Johnson-Mehl-Avrami-Kolmorgorov(JMAK) equation. It was confirmed that the dissolved Nb delays the austenite decomposition, whereas, the precipitated Nb accelerates phase transformation during the austenite decomposition.

A DNA Sequence Search Algorithm Using Integer Type Transformation (정수형 변환을 이용한 DNA 서열 검색 알고리즘)

  • Yoon, Kyong-Oh;Cho, Sung-Bae
    • Proceedings of the Korean Information Science Society Conference
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    • 2012.06b
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    • pp.357-359
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    • 2012
  • 초 고성능 바이오 서열 분석 장비 기술의 발달로 대량의 바이오 정보가 쏟아져 나오고 있으며, 바이오산업의 발달로 개인별 유전체 정보에 의한 맞춤의학의 시대가 도래되고 있다. 수많은 서열에 대한 분석에는 많은 저장장치 및 주기억장치가 필요하므로 슈퍼컴퓨터 급의 서버와 대량의 데이터를 빠르게 처리할 수 있는 프로그램이 필요하다. 이러한 분석에는 염기서열 일치 검색과 이를 기반으로 하는 Alignment와 Assembly 분석이 있으며, 이를 수행하는 기존의 알고리즘 및 대부분의 프로그램들은 염기서열을 문자열로 취급하고, 해쉬 인덱스 테이블, Brujin 그래프의 사용, 버러우즈 휠러 변환(BWT) 등의 기법을 활용하여 효율적인 분석을 도모하였다. 본 논문에서는 염기서열을 문자열이 아닌 k-mer 묶음의 정수형 하나로 변환하여 검색함으로써 저장 공간의 크기를 약 28% 이상으로 줄이고 형 변환 상태에서의 검색을 수행할 수 있는 알고리즘을 제안한다. Assembly 분석 프로그램인 CalcGen 프로그램을 개발하여 본 알고리즘의 효용성 및 효율성을 실험을 통해 검증하였다. 이 연구의 결과는 향후 대량의 유전체 염기서열의 효율적 분석과 저장 및 처리에 또 하나의 새로운 접근 방법을 제안하는데에 그 의미를 둘 수 있다.