• 자원환경지질
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• 제29권2호
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• pp.151-158
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• 1996

Rb-Sr isochron ages, Sr and Nd isotopic compositions were determined for late Cretaceous granophyre on the Haenam-Wando areas, the southwestern part of the Yeongdong-Kwangju depression in Korea. The granophyre in the Haenam-Wando areas are distributed in the shape of a resurgent cauldron. Five samples of Haenam granophyre give a defined Rb-Sr whole rock isochron age of $75.7{\pm}7.2Ma$ and Sr initial ratio of $0.70826{\pm}0.00020(2{\sigma})$. Plagioclase, orthoclase and whole rock of Haenam granophyre give a defined Rb-Sr whole rock-mineral isochron age of $67.0{\pm}5.8Ma$ and Sr initial ratio of $0.708880{\pm}0.00028(2{\sigma})$. Five samples of Wando granophyre give a defined Rb-Sr whole rock isochron age of $70.6{\pm}3.3Ma$ and Sr initial ratio of $0.70850{\pm}0.00088(2{\sigma})$. Eight samples of Haenam granophyre give a defined Nd isotope ratios of 0.512180~0.512259 and ${\varepsilon}Nd$ (T) values of -6.53~-8.15, ${\varepsilon}Sr$ (T) values of +51.49~+66.48 and model age of 1.28~1.60 Ga. Four samples of Wando granophyre give a defined Nd isotope ratios of 0.512228~0.512289 and ${\varepsilon}Nd$ (T) values of -6.74~-8.00, ${\varepsilon}Sr$ (T) values of +54.88~+78.98 and model age of 1.14~1.42 Ga.

• 암석학회지
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• 제1권2호
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• pp.124-131
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• 1992

The Sm-Nd isotopic data on the Precambrian gneisses from Gyeonggi and Sobaegsan Massifs are presented and the crustal evolution of the Precambrian basements of the Korean Peninsula is discussed with that of the Precambrian basements of East Asia. Sm-Nd isochron plots on whole rock samples from Sobaegsan Massif give the following ages and initial Nd values. Biotite gneisses: $1.05{\pm}0.07$ Ga with ${\varepsilon}_{Nd}$ (1.05 Ga)= $-12.5{\pm}0.4$ ($2{\sigma}$); granitic gneisses: $1.70{\pm}0.59$ Ga with ${\varepsilon}_{Nd}$ (1.70 Ga)=$+9.5{\pm}6$($2{\sigma}$). Initial Nd isotopic evolution diagram for the Precambrian orthogneisses from Sobaegsan Massif with the Precambrian orthogneisses in northeastern China and Japan reveals the existence of early Archean depleted-mantle in east Asia and suggests the prevalence of nearly common or similar source accountable for these Precambrian gneisses. Such a common source is shown to have LREE-enriched feature and to have been formed from the depleted-mantle in the late Archean of ca. 2.6 Ga. On the other hand, the Sobaegsan granitic gneisses in Korea are concluded to have different evolution history. Our Sm-Nd study clearly discloses that some Precambrian orthogneisses from Korea had evolved from the protolith having the similar or same geochemical properties with the Precambrian orthogneisses in Japan and northeastern China. In addition, crustal formation age of Gyeonggi Massif in southern Korea may be different from that of Sobaegasn Massif.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제21권4호
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• pp.281-293
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• 2014

We investigate long-term motions of the cable when cable has different types of periodic forcing term. Various different types of solutions are presented by using the 2nd order Runge-Kutta method under various initial conditions. There appeared to be small- and large-amplitude solutions which have different nodal structure.

• 암석학회지
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• 제10권1호
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• pp.27-35
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• 2001

지리산 지역의 차노카이트는 외국의 많은 예와 같이 고도의 변성작용을 받은 선캠브리바기 지역에 나타나며 회장암과 함께 산출된다. 차노카이트 전암 및 석류석에 대한 Sm-Nd 연대측정 결과 괴상 차노카이트는 $1827\pm$32(2$\sigma$) Ma, 엽리상 차노카이트는 $1820\pm$22($2\sigma$) Ma를 나타낸다. $\varepsilon_{Nd}$(T)는 각각 -5.5$\pm$0.2와 -$6.0\pm$0.5 이며, 이 연대로 계산한 $^{87}$ $Sr^{86}$ Sr 초기치는 각각 0.71319, 0.71532이다. 괴상 및 엽리강 차노카이트가 동일한 연대와 Nd 초기치, 유사한 Sr 초기치를 가지는 것은 비록 이들의 현재 조직은 다르지만 균질한 동위원소 조성을 갖는 동일한 암체로부터 같은 시기의 변성작용에 의해 만들어진 것으로 해석된다. 차노카이트의 Nd 초기치, Sr 초기치는 맨틀의 값과는 매우 다르며 지각의 영향을 나타낸다. 회장암체 내에 배태한 함티타늄 회장암질암체에서 분리한 석류석, 사장석 및 유색광물 부분에 대한 Sm-Nd 연대측정 결과는 $1792\pm$90($2\sigma$) Ma, 이트와 회장암의 광물연대가 오차범위 내에서 같은 점은 이들 사이에 성인적 관계가 있을 가능성을 시사한다. 그러나 차노카이트와 회장암의 화화적 조성은 분화관계로는 설명되지 않으며, 또한 Nd 동위원소 초기치및 Sr 등위원소 초기치 역시 다르다. 이는 이들이 다른 기원물질에서 만들어 졌음을 의미하며 둘 사이의 시기적 연관성은 외국 다른 지역의 연구결과들과 마찬가지로 차노카이트의 생성에 회장암이 주된 열원으로 작용하였을 가능성을 시사한다.

• 자원환경지질
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• 제30권3호
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• pp.249-262
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• 1997

The Sr and Nd isotopic compositions of two foliated granitic plutons located in the Chonju and Sunchang area were determined in order to reconfirm the intrusion ages of granitoids and to study the sources of granitic magmas. The best defined Rb-Sr isochron for the whole rock samples of the Chonju foliated granite (CFGR) give an age of $284{\pm}12Ma$, suggesting early Permian intrusion age. In contrast, the whole rock Rb-Sr data of the Sunchang foliated granite (SFGR) scatter widely on the isochron diagram with very little variation in the $^{87}Rb/^{86}Sr$ ratios and, therefore, yield no reliable age information. Futhermore they show the concordance of mineral and whole rock Rb-Sr isochron and divide into two linear groups with roughly the same slopes and significantly different $^{87}Sr/^{86}Sr$ ratios, indicating some kind of Rb-Sr distortion in whole rock scale and a difference in source material and/or magmatic evolution between two subsets. The reconstructed isochrons of 243 Ma, which was defined from the proposed data by the omission of one sample point with significantly higher $^{87}Rb/^{86}Sr$ ratio than the others, and 252 Ma, from the combined data of it and some of this study, strongly suggest the possibility that the SFGR was intruded appreciably earlier than had previously been proposed, although the reliability of these ages still questionable owing to high scatter of data points and, therefore, further study is necessary. All mineral isochrons for the investigated granites show the Jurassic to early Cretaceous thermal episode ranging from 160 Ma to 120 Ma Their corresponding initial $^{87}Sr/^{86}Sr$ ratios correlate well with their whole rock data, indicating that the mineral Rb-Sr system of the investigated granites was redistributed by the postmagmatic thermal event during Jurassic to early Cretaceous. The initial ${\varepsilon}Sr$ values for the CFGR (64.27 to 94.81) tend to be significantly lower than those for the SFGR (125.43 to 167.09). Thus it is likely that there is a marked difference in the magma source characteristics between the CFGR and the SFGR, although the possibility of an isotopic resetting event giving rise to a high apparent initial ${\varepsilon}Sr$ in the SFGR can not be ruled out. In contrast to ${\varepsilon}Sr$, both batholiths show a highly resticted and negative values of initial ${\varepsilon}Nd$, which is -14.73 to -19.53 with an average $-16.13{\pm}1.47$ in the CFGR and -14.78 to -18.59 with an average $-17.17{\pm}1.01$ in the SFGR. The highly negative initial ${\varepsilon}Nd$ values in the investigated granitoids strongly suggest that large amounts of recycled old continental components have taken part in their evolution. Furthermore, this highly resticted variation in ${\varepsilon}Nd$ is significant because it requires that the old crustal source material, from which the granitoid-producing melts were generated, should have a reasonably uniform Nd isotopic composition and also quit similar age. Calculated T2DM model ages give an average of $1.83{\pm}0.25Ga$ for CFGR and $1.96{\pm}0.19Ga$ for SFGR, suggesting the importance of a mid-Proterozoic episode for the genesis of two foliated granites. Although it is not possible to determine precisely the source rock compositions for the investigated foliatic granites, the Sr-Nd isotopic evidences indicate that midcrustal or less probably, a lower crustal granulitic source could be the most likely candidate.

• 대한자원환경지질학회:학술대회논문집
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• 대한자원환경지질학회 2000년도 춘계 공동학술발표회
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• pp.110-110
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• 2000

Temporal and spatial distribution patterns of the magmatic rocks and associated ore deposits in the Mesozoic magmatic - metallogenic belt along the Yangtz River, Anhui Province are used to determine and discuss the crust - mantle interaction processes. The magmatic rocks are Cu - Au mineralized high - K calc - alkalic intermediate ¬acidic (CAK) and Fe - Cu mineralized high - Na alkalic - calc intermediate - basic intrusive rocks (FCN) in the central part of the belt and grade to Cu - Mo - Pb - Zn - Ag mineralized calc - alkalic granitoids (CMG) and A - type granites (AG) in the southern and northern parts of the belt. Samples from the CAK and CMG yield Rb - Sr isochron ages of 137 - 140Ma with $(^{87}Sr/^{86}Sr)_{o}$ = 0.7060 - 0.7101, while those from the FCN and AG yield the ages of 120 - 129Ma with $(^{87}Sr/^{86}Sr)_{o}$ = 0.7047 - 0.7077. The Sr isotope ratios, CriTh ratios 0.4 - 3.1), Eu/Eu* ratios < 0.79 - 1.05) and initial epsilon (Nd) values (-16.6 - -6.3) for the CAK and CMG are consistent with magma derivation from old metamorphic basement rocks rich in metallogenic elements through a two - stage process of mantle - derived magma underplating caused by primary lithosphere extension and subsequent partial melting. On the basis of Sr isotope data, CriTh ratios (3.4 - 13.8), Eu/Eu* ratios (0.86 - 1.13) and initial epsilon (Nd) values (-7.7 - +1.4), the FCN and AG are considered to be formed through syntexis with material input from the mantle that resulted from further lithosphere extension followed by mantle - derived magma underplating on a large scale.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.531-536
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• 2003

In this paper, a redesigned guidance and control system for a lunar lander is presented. In past studies, the authors developed a trajectory and attitude control system which achieves the vertical soft landing on the lunar surface. It is confirmed that the system has a good tracking ability to a predefined profile and good robustness against a thruster failure mode where a partial failure of clustered engines was assumed. However, under the previous control laws, the landing point tends to be shifted, in response to the system parameter values, from a target point. Also, an unbalanced moment due to a thruster failure mode was not considered in the simulation. Therefore, in this study, the downrange control is added to the system to enable the vehicle to land at a pre-assigned target point accurately. Furthermore, inhibiting the effect of the unbalanced moment is attempted thorough redesigning the attitude control system. A numerical simulation was performed to confirm the ability of the proposed system with regard to the above problems. Moreover, in the past simulations, a low initial altitude was assumed as an initial condition: in this study, however, the performance of the proposed system is examined over the whole trajectory from an initial altitude of 10 [km] to the lunar surface.

• 한국지구과학회지
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• 제22권1호
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• pp.1-9
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• 2001

본 연구는 옥천대 중앙부에 위치한 전주 엽리상화강암체에 대한 전암화학 및 Sr, Nd동위원소 조성을 측정하여 화강암체의 관입시기와 기원을 파악코자 하였다. 본 암체는 중립 내지 조립질의 엽리상 흑운모 화강암으로 중성 내지 산성 조성을 보여 비교적 넓은 조성변화를 갖는다. 칼크알칼리 계열에 속하고, 대륙 및 호상열도의 지구조환경에서 형성된 화강암류의 특징을 나타낸다. 분석된 시료를 이용한 Rb-Sr 전암연령은 168.2${\pm}$8 Ma(2${\sigma}$)이고, Sr 초생치는0.71354${\pm}$0.00031로서 중생대 쥬라기 중기 관입암체에 해당된다. $^{143}$Nd/$^{144}$Nd 비는 0.511477${\sim}$0.511744의 범위를 갖고 있다. 168.2Ma로 표준화한 ${\varepsilon}$Nd 값은 -15.4${\sim}$-21.2, ${\varepsilon}$Sr 값은 +108.8${\sim}$+l42.6이고, 맨틀에 대한 모델연령은 1.82${\sim}$2.89Ga이다. 이러한 동위원소 조성은 전주 엽리상화강암체를 형성한 마그마가 대륙 지각물질의 부분용융산물임을 나타낸다.

• Journal of Ship and Ocean Technology
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• 제11권3호
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• pp.1-13
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• 2007

A semi-submersible drilling rig is regarded as one of the typical offshore structures operated in the field with moderate environments such as the Gulf of Mexico, Brazil, and West Africa. Its typical roll and pitch natural periods are around 30 seconds, which avoids prevailing regions of the wave energy spectrum, and their responses in waves are quite acceptable for common operation conditions. But large roll and pitch motions can be induced by wave difference frequency energy spectrum if the metacentric heights of a semi-submersible decrease to small values in some loading conditions, and it is because the roll and pitch natural periods increase and approach to the region where the spectral density of the low frequency wave drift moment has significant value. This paper describes the low frequency roll motion of a semi-submersible that are excited by the wave 2nd order difference frequency energy by a series of model experiments. From the model tests with several different initial metacentric heights (GM), it was observed that a semi-submersible can experience large roll motion due to the wave group spectrum.

• 한국식품영양과학회지
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• 제29권5호
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• pp.822-831
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• 2000

Application of omija(Schizndra chinensis Baillon) to improve the quality and preservation of nabka kimchi was attempted and the optimal amount of omija level and its effect on the sensory and microbiological properties of nab마 kimchi during fermentation were examined. Effects of omija juice which had been prepared by extracting omija seeds for 9 hr at room temperature (22.5$\pm$0.5$^{\circ}C$) with different ratios (0.5, 1.0, 1.5, 2.0%;w/v) of water were examined against control (kimchi prepared without omija). Organoleptic and microbiological properties of nabak kimchi were measured up to 25 days at 1$0^{\circ}C$ after preparation. Sensory properties were evaluated in the aspects of both acceptability and intensity characteristics. In whole, 0.5 and 1.0% treatments showed higher values of evaluation, compared to control, 1.5, and 2.0% treatments throughout the fermentation period. As fermentation progresses, however, sample of 1.0% treatment ranked first between day 4 to 7 and also so did sample of 0.5% treatment along with 1.0% treatment from behind day 10. As for color, control, 0.5% treatment, and 1.0% treatment were more favored than rest of the samples. In texture, 2.0% treatment showed the highest values, whereas control was rated the lowest. In the intensity of characteristics 1.5% and 2.0% treatments showed higher values except sweet taste in which 1.0% treatment ranked top during the initial 7 days and then 0.5% treatment took the first place at behind day 10. total cell counts and number of lactic acid bacteria were gradually increased and then decreased showing the maximum levels of microbial counts on different days, to say, day 2 for control and 0.5% treatment nd day 7 for 1.0, 1.5 and 2.0% treatments. The application of omija juice in nabak kimchi enhanced eating qualities of the fermented product and the fermentation-retarding effect of omija juice was clearly shown during the initial seven days of fermentation. The optimum levels of omija juice in nabak kimchi obtained through experiments were between 0.5 to 1.0% for color, fermentation-retarding effects, and savory taste of the product.