• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.1729-1733
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• 2010

본 연구에서는 7개 지점(여주, 적성, 왜관, 진동, 공주, 구례2, 나주)에 대해 유사량 특성 분석을 수행하였다. 부유사량은 강우가 집중되는 홍수기와 이의 전 후시기인 저 평수기(2회)로 나누어 왕복수심적분법(D-74)으로 측정하였고, 하상토는 BM-54, Grab Sampler(60 L), 선격자 등을 이용하여 홍수기 전 후로 2회 채취하였다. 채취된 시료는 그 목적에 따라 여과법(부유사농도), BW관법(부유사입도분포), 체분석법(하상토입도분포)으로 분석하였고, 그 결과로 작성된 평균 부유사농도 및 Oden Curve와 입도분포곡선과 수리량(수위, 유속, 측정수심, 수면폭, 수면경사, 수온)등의 자료를 이용하여 총유사량(미측정구간의 유사량 포함)을 추정(실측+계산: Modified Einstein)하였다. 총유사량 추정시, 세류사량을 제외한 부유사량을 적용하였다. 유량-부유사농도와 부유사량 및 총유사량 관계에 대한 결과는 다음과 같다: 1) 하나의 강우사상의 수위 상승-첨두-하강에 대한 측정성과는 대체적으로 Loop 형태를 보였고 이로 인해 일부 지점에서 측정성과들 간의 산포도가 다소 크게 나타났으며 수위 하강 때보다 상승시 초기 탁도의 증가 현상으로 부유사농도가 더 높은 것을 볼 수 있었다. 2) 유량-부유사농도, 부유사량, 총유사량 관계에서 왜관과 공주 지점의 경우, 첨두 수위에서 값들의 최고치를 보였고 나머지 지점들은 첨두 수위의 앞선 측정 수위에서 최고치를 보였다. 이는 강우사상별, 강우강도, 댐 방류량, 수위 상승-하강부, 유량에 따른 부유사농도와 부유사량의 특성이 각각 다른 점과 총유사량 추정시, 추정방법에서 추천하는 범위에서 벗어나는 자료를 적용해서 나타나는 결과로 판단된다. 여기서 유량, 수심, 하상토의 입도크기 등 자료의 범위가 추정공식들이 추천하는 범위에서 벗어나면 그 분석 결과도 서로 다르게 나타난다는 것은 그만큼 총유사량 공식의 범용성이 적다는 것을 의미한다. 이러한 점에서 때로는 자료 전체에 대해 전반적으로 양호한 결과를 보이는 공식보다는 정확한 답을 원하는 자료의 범위 내에서 예측하는 공식을 선정하는 것이 필요하다. 즉, 공식을 적용하여 유사량을 추정하고자 하는 하천이나 수로의 특성에 맞는 유사량 공식을 선정하는 것이 중요하다는 것이다.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.8 no.2
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• pp.137-145
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• 1996

Effects of nonlinear terms on the generation of M$_2$ tide residual elevation and M$_4$ tide in the Yellow Sea and the East China Sea are investigated using a depth-integrated two-dimensional nonlinear M$_2$tidal model. The model domain (117$^{\circ}$E-130$^{\circ}$E, 24$^{\circ}$N-41$^{\circ}$N) covers the whole region of the Yellow Sea and the East China Sea with grid resolution of 1/6$^{\circ}$ in longitude and 1/8$^{\circ}$in latitude. A radiational boundary condition is used along the open boundaries. Calculations show that advection terms yield negative residual elevation, while shallow-water terms in continuity equation yield positive residual elevation. The contribution of both advection terms and shallow-water terms to tile generation of the M$_4$ constituent is more than 90 percents, but that of quadratic bottom friction terms to the M$_4$ constituent is comparatively small.

• Applied Chemistry for Engineering
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• v.7 no.5
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• pp.888-901
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• 1996

Oxidations of cyclopentene and of 1-pentene with air have been studied on a V/Mo/P/Al/Ti-mixed oxide catalyst in a fixed bed integral reactor. At high levels of conversion maleic anhydride was in each case produced as the major organic product, along with minor amounts of phthalic anhydride and, only starting from 1-pentene, also of citraconic anhydride. At lower levels of conversion a total of 30 organic products have been identified, some of which may be intermediates on the way from the substrates to the three anhydrides mentioned above. Based on the dependence of selectivities of the organic products on conversion, reaction schemes for the formation of maleic anhydride, phthalic anhydride and citraconic anhydride have been proposed. Oxidation at $310^{\circ}C$ led to increasing conversions and selectivities for maleic anhydride with decreasing space velocities. The highest selectivities for maleic anhydride were obtained at conversion of ca. 100%. Oxidation at a constant space velocity of $2{\cdot}10^4h^{-1}$ led to increasing conversions with increasing temperatures in the range of $300^{\circ}C{\sim}420^{\circ}C$, while the selectivity for maleic anhydride passed through a maximum value of ca. 39% at $370^{\circ}C$ in the oxidation of cyclopentene and a maximum value of ca. 30% at $400^{\circ}C$ in the oxidation of 1-pentene.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.10
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• pp.985-993
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• 2015

Free-piston Stirling engines (FPSEs) have attracted much attention in the renewable energy field as a key device in the conversion from thermal to mechanical energy, and in the recycling of waste energy. Traditional Stirling engines consist of two pistons that are connected by a mechanical link, while FPSEs are formed as a vibration system by connecting each piston to a spring without a physical link. To ensure the correct design and control of operations, this requires elaborate dynamic-performance predictions. In this paper, we present the performance-prediction methodology using a linear and nonlinear dynamic analytical model considering the external load of FPSEs. We perform linear analyses to predict the operating point of the engine using the root locus technique. Using nonlinear analysis, we also predict the amplitude of pistons by performing numerical integration considering both the linear and nonlinear damping terms of the external load. We utilize the predicted dynamic behavior to predict the engine performance. In addition, we compare the experiment results and existing model predictions for RE-1000 to verify the reliability of the analytical model.

• Nuclear Engineering and Technology
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• v.18 no.1
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• pp.1-8
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• 1986

A magnetic quadrupole doublet was fabricated for use at the pre-target position of SNU 1.5MV Van de Graaff accelerator and then its optical characteristics were measured and analysed. The physical dimensions are: pole length 180mm, aperture radius 25mm, pole tip radius 28.75mm. Material for poles and return yokes is carbon steel KS-SM40C. Coils have 480 turns per one pole and air-cooling is adopted. Applying the d.c. current 2.99$\pm$0.03A to the lens, and using the Hall probe, magnetic field elements $B_{\theta}$ , $B_{\gamma}$, were measured at the selected Points along each coordinate direction r,$\theta$, z. From the area integration and orthogonal polynomial fitting for the measured data, the magnetic Field gradient G=566.3$\pm$2.1 gauss/cm at lens center, the effective length L=208.3$\pm$1.44mm along the lens axis have been obtained. The harmonic contents were determined up to 20-pole from the generalized least squares fitting. The results indicate that sextupole/quadrupole is below 1.4$\pm$0.9% and all the other multipoles are below 0.5% in the region within 18mm radius at the center of lens.

• Journal of Plant Biology
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• v.3 no.1
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• pp.16-25
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• 1960

HARN, Chang Yawl (Chonnam U. Kwangju, Korea): Siudies on the dimorpism of the Perisicaria senticosa Nakai-Kor. jour. Bot. 3(1) 16-25 During his researches regarding the morphological and physiological properties of Polygonecenae, the author has found that the species, Persicaria senticosa, aiso, besides the heterostylous plants of Polygonum family, Fagopyrum esculentum, and Persicaria japonica which was recently verified by the author as dimorphic, shows the typical floral structure of heterostylism, the description of which is not found in taxonomical works. Further research on this species have revealed that this plant, despite pressessing characteristic structural dimorphism, does not exhibit even the slight signs of heterostlylous properties physiologically. This is a deviation from the usual behavior of normal heterostylous plants. What is interesting is the fact that the physiological behavior of this species is quite contrary to that of P. japonica which is considered to be the most highly specialized dimorphic plant. Thus it is assurred that if some species of this family had taken a heterostylic form in its course of development from autogamy to allogamy, P. seoticosa would be the least differentiated type of dimorphic forms among the three heterostylous plants, including buckwheat, of this family. The results obtained in this experiment are summarized as follows: 1) P. senticosa has two forms of flower, one, long style-short stamened; the other, short style-long stamened. Not only conspicuous is this primary difference, but the secondary difference, such as pollen grain size, is noticeable between long and short styled individuals, thus expressing structurally the definite trait of a dimorphic plant. 2) Structural alteration of floral parts towards dimorphism has preceeded far less in comparison with those of the P. japonica and F. esculentum. 3) Elaborate studies on fertility reveal that this species does not show the slightest sign of the physiological characteristics of dimorphic plants. In other words, regardless of the modes of combinations, legitimate and illegitimate, fertilization and fruit setting flourish unimpaired. 4) Growth of pollen tubes apparently parallels the results in the fertility, tubes reaching ovary approximately 30 minutes after pollination both in legitimate and illegitimate combinations. Pollen tube penetration appears to be comparatively rapid. 5) A slight difference in the growth of pollen tube seems to exist between legitimate and illegitimate combinations, legitimate union giving slightly faster tube penetration. 6) In the present experiment it was clarified that P. senticosa, known to possess one form of flower in taxonomy, is in reality dimorphic plant having two of flowers. Although this species is definitely heterostylous in floral structure, physiological evidence and pollen tube behavior show that the differentiation of this plant toward the dimorphism has apparently proceeded slightly except for some parts of floral organ. In ordinary heterostylous plants it is a matter of common occurrence that when illegitimately cmbined, there is poor or no fertility, Contrary to the universal property of heterostylous plants, no difference is observed in the fertility and pollen tube growth between the legitimate and illegitimate combinations in the case of P. senticosa. Compared to the P. japonica and F. esculentum, which are supposed to have undergone high degree of dimorphic differentiation, it is an unavoidable conclusion that P. senticosa has not yet developed as a heterostyle plant except for some of its floral parts. If P. japonica is assumed to be the most differentiated type of hetenostylous plant, thenthe P. senticosa would be regarded as the primitive, retaining still the self-fertile nature so common to the Polygonum genus. In nature, however, this plant has a better chance to be pollinated legitimately owing to the two forms of flowers than to be pollinated illegitimately. The author is indebted to Dong Chul, Kim as well as other members of the Department of Plant Breeding and Genetics of Chonnam National University for their efforts out the laborious experiments during the course of the present studies.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.3 no.4
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• pp.109-122
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• 1983

An accurate thick beam element (TB4) which includes the effects of the shear deformation and rotatory inertia has been degenerated from the three dimensional continuum by employing the Timoshenko beam assumptions. The proposed TB4 element has four nodes and two degrees of freedom at each node, totally eight degrees of freedom. The transverse deflection W and plane rotation ${\theta}$ with the cubic interpolation functions are selected as nodal variables. The element characteristics are formulated by discretizing the beam equations of motion, using the Galerkin weighted residual method, and are numerically integrated by the reduced shear integration technique, using the three-point Gauss quadrature with the various shear coefficients. Several numerical examples are analyzed to demonstrate the accuracy and the monotonic convergence behavior of the proposed TB4 beam element. The result indicates that the TB4 element shows the more excellent performance and the monotonic convergence behavior than the other existing Timoshenko beam type elements for the whole range of the beam aspect ratios, in both static and free vibration analyses.

• International Union of Geodesy and Geophysics Korean Journal of Geophysical Research
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• v.22 no.1
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• pp.1.1-15
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• 1994

The transports of the seasonal freshwater and salt from surface to 500 m depth in the tropical Atlantic Ocean are derived from the equations of the continuity and saltconservation, respectively. The freshwater transport is obtained by southward integration of the divergence of surface freshwater flux, using climatological freshwater(i. e. precipitation, evaporation, and river discharge) data. The annual freshwater transport is northward, ranging from 0 Sv near the equator to 0.3 Sv at $12^{\circ}{\;}N{\;}and{\;}20^{\circ}{\;}S$. The seasonal meridional transport amounts of freshwater range from 1.35 Sv to-0.45 Sv. The strong northward freshwater transports prevail for the intraseasonal period summer to fall. This seasonal cycle is caused by the shifts of the ITCZ as well as the changes in the local freshwater storage. Annual and seasonal salt transports are calculated from objectively analyzed historical (1900-86) salinity observations. The annual salt flux in the ocean zero, showing that the salt flux by horizontal advection balances the flux by horizontal diffusion. The salt flux due to the diffusion is northward, and has a maximum of $5{\;}{\times}{\;}10^6kg/s$ at 15oN. Seasonal transport amounts of salt range from $30{\;}{\times}{\;}10^6kg/s{\;}to{\;}-35{\;}{\times}10^6kg/s$. The direction of the seasonal salt transports is northward except for the intraseasonal period summer to fall.

• Korean journal of applied entomology
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• v.26 no.3 s.72
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• pp.123-132
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• 1987

Vertical distribution of ants were studied in Jiri mountain by collecting 15 times at 42 sites for 3 years since 1984. 31 species of 16 genera in 3 subfamilies were collected during the survey. The following 6 species, i.e., Formica japonica, F. lemani, Lasius niger, L. alienus, Pheidole fervida and Myrmica ruginodis were dorminant one, but 9 species such as Leptothorax congruus, Pheidole nodus, Aphanogaster japonica, Jollenhovia emeryi, Camponotus tokioensis, Polyrhachis lamellidens, Phagiolepsis mandjurica, myrmica yessensis and M. sulcinodis were rare species. The ant of Jiri mountain consisted of 16 species in Formicinae, 13 species in Myrmicinae and 2 species in Ponerinae. Ponerinae was distbriuted as far as 1,800m, but Myrmicinae and Formicinae to 1,915m. Only 8 species-Myrmica ruginosis, Myrmica sp., M. yessensis, M. sulcinodis, Leptothorax acevorum, Formica japonica, F. lemani and Camponotus japonicus-were collected at the submit of Jiri mountain, Cheonwangbong. The vertical distribution of C. atrox was ranged from 800m to 1,800m.

• Investigative Magnetic Resonance Imaging
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• v.1 no.1
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• pp.119-124
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• 1997

Purpose: To assess the utility of magnetic resonance(MR) cerebral blood volume (CBV) map in the evaluation of brain tumors. Materials and Methods: We performed perfusion MR imaing preoperatively in the consecutive IS patients with intracranial masses(3 meningiomas, 2 glioblastoma multiformes, 3 low grade gliomas, 1 lymphoma, 1 germinoma, 1 neurocytoma, 1 metastasis, 2 abscesses, 1 radionecrosis). The average age of the patients was 42 years (22yr -68yr), composed of 10 males and S females. All MR images were obtained at l.ST imager(Signa, CE Medical Systems, Milwaukee, Wisconsin). The regional CBV map was obtained on the theoretical basis of susceptibility difference induced by first pass circulation of contrast media. (contrast media: IScc of gadopentate dimeglumine, about 2ml/sec by hand, starting at 10 second after first baseline scan). For each patient, a total of 480 images (6 slices, 80 images/slice in 160 sec) were obtained by using gradient echo(CE) single shot echo-planar image(EPI) sequence (TR 2000ms, TE SOms, flip angle $90^{\circ}$, FOV $240{\times}240mm,{\;}matrix{\;}128{\times}128$, slice-thick/gap S/2.S). After data collection, the raw data were transferred to CE workstation and rCBV maps were generated from the numerical integration of ${\Delta}R2^{*} on a voxel by voxel basis, with home made software (${\Delta}R2^{*}=-ln (S/SO)/TE). For easy visual interpretation, relative RCB color coding with reference to the normal white matter was applied and color rCBV maps were obtained. The findings of perfusion MR image were retrospectively correlated with Cd-enhanced images with focus on the degree and extent of perfusion and contrast enhancement. Results: Two cases of glioblastoma multiforme with rim enhancement on Cd-enhanced Tl weighted image showed increased perfusion in the peripheral rim and decreased perfusion in the central necrosis portion. The low grade gliomas appeared as a low perfusion area with poorly defined margin. In 2 cases of brain abscess, the degree of perfusion was similar to that of the normal white matter in the peripheral enhancing rim and was low in the central portion. All meningiomas showed diffuse homogeneous increased perfusion of moderate or high degree. One each of lymphoma and germinoma showed homogenously decreased perfusion with well defined margin. The central neurocytoma showed multifocal increased perfusion areas of moderate or high degree. A few nodules of the multiple metastasis showed increased perfusion of moderate degree. One radionecrosis revealed multiple foci of increased perfusion within the area of decreased perfusion. Conclusion: The rCBV map appears to correlate well with the perfusion state of brain tumor, and may be helpful in discrimination between low grade and high grade gliomas. The further study is needed to clarify the role of perfusion MR image in the evaluation of brain tumor.