• Journal of Korean Neurosurgical Society
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• v.63 no.5
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• pp.607-613
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• 2020

Objective : Spontaneous intracranial hemorrhage is a life-threatening disease, and non-lesional spontaneous intraparenchymal hemorrhage (nIPH) and aneurysmal subarachnoid hemorrhage (aSAH) are the leading causes of spontaneous intracranial hemorrhage. Only a few studies have assessed the association between prior physical activity or triggering events and the occurrence of nIPH or aSAH. The purpose of this study is to investigate the role of specific physical activities and triggering events in the occurrence of nIPH and aSAH. Methods : We retrospectively reviewed 824 consecutive patients with spontaneous intracranial hemorrhage between January 2010 and December 2018. Among the 824 patients, 132 patients were excluded due to insufficient clinical data and other etiologies of spontaneous intracranial hemorrhage. The medical records of 692 patients were reviewed, and the following parameters were assessed : age, sex, history of hypertension, smoking, history of stroke, use of antiplatelet or anticoagulation agents, season and time of onset, physical activities performed according to the metabolic equivalents, and triggering event at onset. Events that suddenly raised the blood pressure such as sudden postural changes, defecation or urination, sexual intercourse, unexpected emotional stress, sauna bath, and medical examination were defined as triggering events. These clinical data were compared between the nIPH and aSAH groups. Results : Both nIPH and aSAH most commonly occurred during non-strenuous physical activity, and there was no significant difference between the two groups (p=0.524). Thirty-two patients (6.6%) in the nIPH group and 39 patients (8.1%) in the aSAH group experienced triggering events at onset, and there was a significant difference between the two groups (p=0.034). The most common triggering events were defecation or urination in both groups. Conclusion : Specific physical activity dose no affect the incidence of nIPH and aSAH. The relationship between the occurrence of intracranial hemorrhage and triggering events is higher in aSAH than nIPH.

• Journal of Nutrition and Health
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• v.39 no.7
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• pp.617-623
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• 2006

The mortality and morbidity rate of hemodialysis patients (HD) remain high. Among many factors, protein and calorie malnutrition has been shown to be a major risk factor for increased mortality in the HD patients population. Malnutrition can be caused by insufficient amino acid intake, nutrient losses in dialysate, oxidant stress and muscle catabolism. In this study, we evaluated the association of markers of nutritional status and essential amino acids intake in HD patients. We investigated nutritional status of 41 HD patients (mean age: $64.2\;{\pm}\;11.5\;y$, men: 24, women: 27) by measuring anthropometric, biochemical parameters and food intakes by using 24 hr recall methods. Subject's total energy intake and total protein intake were $1,648.0\;{\pm}\;397.31\;kcal/day,\;79.2\;{\pm}\;27.2\;g/day$:, respectively. The animal protein intake was $42.7\;{\pm}\;22.1\;g/day$, essential amino acids intake was $23.4\;{\pm}\;9.92\;g/day$, and the ratio of essential amino acids to total protein intake was $29.6\;{\pm}\;5.42%$. There were significantly positive correlation between muscle mass and lean body mass with serum creatinine level (r=0.435, p<0.01; r=0.435, p<0,01). There were also significant positive correlation in muscle mass and lean body mass with pre hemodialysis blood urea nitrogen (preHD BUN) (r=0.329, p<0.05; r=0.329, p<0.05). There were no significant correlation in total energy intake and total protein intake per kg ideal body weight (IBW) to muscle mass and lean body mass. However, there were significantly positive correlation between the ratio of essential amino acids and muscle mass and lean body mass (r=0.368, p<0.05; r=0.405, p<0.01). And serum hematocrit concentration was positively correlated with the ratio of essential amino acids (r=0.032, p<0.05). The results of this study indicate that strong associations exist in essential amino acid intakes with malnutrition than total protein intakes in HD patient. In conclusion, specialized nutrition education should be necessary to efficiently improve the quality of protein intakes.

• Korean Journal of Veterinary Research
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• v.48 no.3
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• pp.337-345
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• 2008

There are accumulating evidences that high levels of dietary iron may play a role in colon carcinogenesis. Elevated iron status has been associated with oxidative stress. Phytic acid (PA) functions as an antioxidant by chelating divalent cations and prevents formation of reactive oxygen species responsible for cell injury and carcinogenesis. The protective effect of PA was investigated on formation of aberrant crypt foci (ACF) induced by azoxymethane (AOM) in iron-overloaded male F344 rats. After acclimation with AIN-93G purified diet (35 ppm Fe, normal control diet) for one week, animals were fed iron-overloaded diet (350 ppm Fe) and PA (0.5% or 2% PA in water) for 8 weeks. Animals received two (1st and 2nd week) injections of AOM (15 mg/kg b.w.) to induce colonic ACF. The colonic mucosa was examined for the total numbers of aberrant crypt (AC) and ACF after staining with methylene blue. The blood and serum were analyzed with a blood cell differential counter and an automatic serum analyzer. Iron-overloaded diet increased the concentration of iron in liver of the rats. But iron-related parameters in blood were not changed among experimental groups. The numbers of ACF per colon and AC per colon were $178.8{\pm}33.2$ and $448.4{\pm}110.2$ in the iron-overloaded F344 rats. The total AC was significantly increased, compared with normal-diet AOM control group (p < 0.05). The treatments of PA at the dose of 0.5% slightly decreased the number of ACF and AC per colon to $153.6{\pm}29.5$ and $396.3{\pm}107.5$. However, there were no significant differences in the total numbers of ACF and AC between the AOM control group and PA (0.5% or 2%)-treated groups. These results suggest that PA may not affect the formation of ACF or AC induced by AOM in ironoverloaded F344 rats.

• Journal of the Korean Chemical Society
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• v.23 no.4
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• pp.217-236
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• 1979

The author's theory for plastic deformation was applied to superplastic alloys (Zn-Al eutectoid, Al-Cu, Pb-Sn, Sn-Bi, Mg-Al eutectics). The plastic deformation of the superplastic alloys could be described by two Maxwell models connected in parallel which represent two grain boundary flow units. The flow units are characterized by the two parameters $X_{gj}/{\alpha}_{gj}\;and\;{\beta}_{gj}$ (j=l or 2, g signifies the grain boundary) the values of which were obtained by applying our flow equation [Eq. (5)] to experiment. We confirmed that our flow equation describes the superplasticity very well. The curve of strain rate sensitivity m (=${\partial}\;In\;f/{\partial}\;In\;\dot{s})\;vs.\;-In\dot{s}$, where f and s are stress and strain rate, respectively, showed two peaks corresponding to flow unit gl and g2, the separation of the two peaks is determined by the difference between ${\beta}_{g1}\;and\;{\beta}_{g2}$. The condition of superplasticity is also determined by ${\beta}_{gj}$, which satisfies $\dot{s}_{mj}{\leqslant}1.53}{\beta}_{gj}$ [Eq.(13)], where $\dot{s}_{mj}$ is the s of the jth unit at the peak. The grain size dependence of ${\beta}_{gj}$ is described by $ln({\beta}_{gj})^{-1}$=alnx+b [Eq. (16)], where x is the grain size, and a and b are constants. The activation enthalpy for each flow unit, ${\Delta}H_{gj}^{\neq}$ was also determined from the temperature dependence of ${\beta}_{gj}$ which is proportional to the relaxation time of the j th unit. Since the superplasticity is determined by Eq. (13), and since ${\beta}_{gj}$ and ${\Delta}H_{gj}^{\neq}$ are related, we obtained the conclusion that superplasticity occurs in the system having small ${\Delta}H_{gj}^{\neq}$ values. The Aej values were equal to the activation enthalpies of grain boundary self-diffusion of the component atoms of the alloys, this accords with our proposed flow mechanism. The ${\Delta}H_{gj}^{\neq}$ value increases with grain size as expected from Eq. (16).

• Journal of Korean Society of Steel Construction
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• v.20 no.2
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• pp.237-246
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• 2008

The cross-sections of continuous multi-span beams sometimes suddenly increase, or become stepped, at the interior supports of continuous beams to resist high negative moments. The three-dimensional finite-element program ABAQUS (2006) was used to analytically investigate the inelastic lateral-torsional buckling behavior of stepped beams subjected to pure bending moment and resulted in the development of design equations. The flanges of the smaller cross-section were fixed at 30.48 by 2.54 cm, whereas the width and/or thickness of the flanges of the larger cross-section varied. The web thickness and height of beam was kept at 1.65 cm and 88.9 cm, respectively. The ratios of the flange thickness, flange width, and stepped length of beams are considered analytical parameters. Two groups of 27 cases and 35 cases, respectively, were analyzed for double and single stepped beams. The combined effects of residual stresses and geometrical imperfection on inelastic lateral-torsional buckling of beams are considered. First, the distributions of residual stress of the cross-section is same as shown in Pi, etc (1995), and the initial geometric imperfection of the beam is set by central displacement equal to 0.1% of the unbraced length of beam. The new proposed equations definitely improve current design methods for the inelastic LTB problem and increase efficiency in building and bridge design. The proposed solutions can be easily used to develop new design equation for inelastic LTB resistance of stepped beams subjected to general loading condition such as a concentrated load, a series of concentrated loads or uniformly distributed load.

• Geotechnical Engineering
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• v.14 no.6
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• pp.93-112
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• 1998

In the present study, 2-D consolidation theory of the dredged clay by means of the horizontal drain method is proposed. The horizontal drain method to install the drains such as plastic drain board within the dredged clay is a soil improvement method to accelerate the consolidation by expelling pore water in the vertical direction along the horizontal drains. Based on the finite strain consolidation theory by Gibson et al., the partial differential equation of 2-D consolidation due to the horizontal drain is derived. The consolidation due to the horizontal drain can be illustrated from combined self-weight consolidation effect and consolidation effect by horizontal drains. For the prediction of consolidation settlement and degree of consolidation numerical analysis is suggested on the basis of Dufort-Frankel finite differential algorithm. Also, the analytical procedures proposed in this study are verified by the model tests, and the predictions of the consolidation settlement and degree of consolidation are compared with the results obtained from the tests for the dredged clay gathering at Siwha site in Ansan, Korea. For the predictions, the relationship void ratio vs effective stress and the relationship permeability vs void ratio of the dredged clay are obtained from the odometer tests. Additionally, the parametric study for consolidation settlement by variations of design parameters related with horizontal drain method is carried out. Based on the results of the parametric study, design .charts for the preliminary design are also proposed.

• Journal of the Korea Concrete Institute
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• v.18 no.5 s.95
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• pp.595-602
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• 2006

An experimental study was conducted to investigate seismic behaviour of post-tensioned(PT) exterior slab-column connections used for the purpose to resist gravity loads only. For these, 2/3-scale, two PT post-tensioned exterior connections with two different tendon arrangement patterns and one conventional reinforced concrete(RC) exterior connection was tested under quasi-static, uni-directional reversed cyclic loading. During the lateral testing, gravity forces transferred to the column were kept constant to closely simulate a moment to shear ratio of a real building. One of the objectives of this study was to assess the necessity and/or the quantity of bottom bonded reinforcement needed to resist moment reversal which would occur under significant inelastic deformations of the adjacent lateral force resisting systems. The ACI 318 and 352 provisions for structural integrity were applied to provide the bottom reinforcement passing through the column for the specimens. Prior test results were also collected to conduct comparative studies for some design parameters such as the tendon arrangement pattern, the effect of post-tensioning forces and the use of bottom bonded reinforcement. Consequently, the impact of tendon arrangement on the seismic performance of the PT connection, that is lateral drift capacity and ductility, dissipated energy and failure mechanism, was considerable. Moreover, test results showed that the amount of bottom reinforcement specified by ACI 352. 1R-89 was sufficient for resisting positive moments arising from moment reversal under reversed cyclic loads. Shear strength of the tested specimens was more accurately predicted by the shear strength equation(ACI 318) considering the average compressive stress over the concrete($f_{pc}$) due to post-tensioning forces than that without considering $f_{pc}$.

• Journal of the Korean Geotechnical Society
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• v.19 no.1
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• pp.209-220
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• 2003

Modification of general Hoek and Brown criterion is carried out to estimate the shaft resistance of drilled shaft socketed into rock mass. Since the general Hoek-Brown criterion can consider the in-situ state of the rock mass, the proposed method, estimating the unit shaft resistance of drilled shafts based on the Hoek-Brown criterion, has increased flexibility compared to other methods exclusively considering uniaxial compressive strength of intact rocks. The proposed method can form the upper and lower bounds, and most culled data (from 21 pile load tests) from the literature can be found between these two bounds. A comparison between the estimated and observed unit shaft resistances shows quite a good correlation even with crude assumptions for the input parameters. The best-fit line drawn from this analysis shows that at the lower strength of intact rocks (up to 10MPa), Horvath and Kenney's equation shows a good correlation with the measured values, and fur strong rocks Rosenberg and Journeaux's equation provides a close estimation with colleted data. The results of parametric studies for GSI and confining stress show that the normalized unit shaft resistance increases with these two factors. In addition, coefficient of the equational form of the estimation can vary with GSI and confining stresses.

• Journal of the Korea Concrete Institute
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• v.19 no.2
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• pp.199-207
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• 2007

Strut-and-tie models for noncontact lap splices are presented and parameters affecting the effective lap length $(l_p)$ and the splice strength are discussed in this paper. The effective lap length along which bond stress is developed is shorter than the whole lap length. The effective lap length depends on the transverse reinforcement ratio $({\Phi})$ and the ratio of spacing to lap length $({\alpha})$. As the splice-bar spacing becomes wider, the effective lap length decreases and, therefore, the splice strength decreases. The influence of the ratio ${\alpha}$ on the effective lap length becomes more effective when the transverse reinforcement ratio is low. Because the slope of the strut developed between splice-bars becomes steeper as the ratio ${\Phi}$ becomes lower, the splice-bar spacing significantly affects the effective lap length. The proposed strut-and-tie models for noncontact lap splices are capable of considering material and geometric properties and, hence, providing the optimal design for detailing of reinforcements. The proposed strut-and-tie model can explain the experimental results including cracking patterns and the influence of transverse reinforcements on the splice strength reported in the literature. From the comparison with the test results of 25 specimens, the model can predict the splice strengths with 11.1% of coefficient of variation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.2
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• pp.153-160
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• 2010

A magnetocardiogram (MCG) is a recording of the biomagnetic signals generated by cardiac electrical activity. Biomagnetic instruments are based on superconducting quantum interference devices (SQUIDs). A liquid cryogenic Dewar flask was used to maintain the superconductors in a superconducting state at a very low temperature (4 K). In this study, the temperature distribution characteristics of the liquid helium in the Dewar flask was investigated. The Dewar flask used in this study has a 30 L liquid helium capacity with a hold time of 5 d. The Dewar flask has two thermal shields rated at 150 and 40 K. The temperatures measured at the end of the thermal shield and calculated from the computer model were compared. This study attempted to minimize the heat transfer rate of the cryogenic Dewar flask using an optimization method about the geometric variable to find the characteristics for the design geometric variables in terms of the stress distribution of the Dewar flask. For thermal and optimization analysis of the structure, the finite element method code ANSYS 10 was used. The computer model used for the cryogenic Dewar flask was useful to predict the temperature distribution for the area less affected by the thermal radiation.