• Korean Journal of Radiology
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• v.25 no.1
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• pp.24-32
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• 2024

Despite improvements in operative techniques and perioperative care, post-hepatectomy liver failure (PHLF) remains the most serious cause of morbidity and mortality after surgery, and several risk factors have been identified to predict PHLF. Although volumetric assessment using imaging contributes to surgical simulation by estimating the function of future liver remnants in predicting PHLF, liver function is assumed to be homogeneous throughout the liver. The combination of volumetric and functional analyses may be more useful for an accurate evaluation of liver function and prediction of PHLF than only volumetric analysis. Gadoxetic acid is a hepatocyte-specific magnetic resonance (MR) contrast agent that is taken up by hepatocytes via the OATP1 transporter after intravenous administration. Gadoxetic acid-enhanced MR imaging (MRI) offers information regarding both global and regional functions, leading to a more precise evaluation even in cases with heterogeneous liver function. Various indices, including signal intensity-based methods and MR relaxometry, have been proposed for the estimation of liver function and prediction of PHLF using gadoxetic acid-enhanced MRI. Recent developments in MR techniques, including high-resolution hepatobiliary phase images using deep learning image reconstruction and whole-liver T1 map acquisition, have enabled a more detailed and accurate estimation of liver function in gadoxetic acid-enhanced MRI.

• The Korean Journal of Nuclear Medicine
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• v.3 no.1
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• pp.19-32
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• 1969

Radioisotope renography was carried out in 564 cases consisting of 150 normal controls, 140 hypertensives, 102 hypertensive nephropathys, 62 chronic renal diseases, non-functioning kidneys. It was aimed to study which parameter of the renogram is most applicable to any definite disease of the kidney. The analytical methods adopted were; Tobe, Spencer, Krueger, Matchida and Takeuchi. In the non-functioning kidney groups, the hemograms and serum nitrogen series were also studied to evaluate the relationships between the renograms and renal anemia. The parameters were; time of maximum amplitude (Tmax), half-time of maximum amplitude ($T\frac{1}{2}$), Kac value calculated from these two parameters in Tobe's method, slopes of Band C phase, B/A and B/C values in Spencer's method, total concentration (T.C.), minute concentration (M.C.) and minute excretion (M.E.) in Krueger's method, Matchida's K value and Takeuchi's renal function Index (R.F.I.). Following were the results: 1. In general, marked differences in the patterns of the renogram were observed between the normal controls and nephropathys. In Tobe's method, each parameter showed statistically significant delay or decrease in patients with hypertensive nephropathys and chronic renal diseases. In Spencer's method, slopes of B and C phase and B/C, also showed the statistically significant decrease in patients with hypertension, hypertensive nephropathys and chronic renal diseases. In Krueger's method, M.C. and ME showed the statistically significant differences between the control and patients with hypertension, hypertensive nephropathys and chronic renal diseases, In Matchida's method, K value showed the statistically significant differences between the control and patients with hypertensive nephropathys and chronic renal diseases. 2. It appeared, therefore, that Tobe's $T\frac{1}{2}$, Kac value, Spencer's slopes of Band C phase, B/A, B/C values, Krueger's T.C., M.C., and M.E. values, Matchida's K value are useful for the differentiation of various renal diseases, however, qualitative analysis of the renogram with one or two parameters is not accurate. 3. In bilateral non-functioning kidney groups, a positive correlation between anemia and nitrogen retention was observed, although the quantitative assessment of the degree of non-functioning was impossible.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.3
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• pp.1-8
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• 2000

This paper presents a simulation model of the Quadrature detector to demodulate FSK signal, which is widely used in wireless paging system for its simple hardware implementation and economics of It fabrication. Quadrature detecter has nonlinear phase characteristic for changes linear changes of input signal frequency. So until now Quadrature detector system analysis remained a difficult problem and performance analysis has not been carried out adequately On these backgrounds, this paper presents the FSK signal demodulation process using Quadrature detector and optimal performance derived from digital simulation technique. First, PSN(Phase Shift Network) which is composed of analog RLC tank circuit is transformed into its equivalent digital transfer function using First-order-hold theorem. Though the demodulated outputs of the Quadrature detector for 4FSK are 4-level signals, only 2 comparators are used and it is shown that optimal performance can be obtained by choosing operation parameter Q value and threshold level decision which are proposed herein.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.3
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• pp.20-28
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• 2002

This paper describes the time sharing type high frequency resonant inviter can be used as power of induction heating. This closed inverter can be obtained output frequency three times than switching frequency by composing three unit inviter of conventional Half-Bridge serial resonant inverter in parallel with input power source also, this reduce switching loss because it has ZVS function. The analysis of the proposed circuit is generally described by using the normailized proposed parameters. The principle of basic operating and the its charasteristics are extimated by the parameters such as switching frequency($\mu$), the variation of Phase angle($\phi$) of Phase-shift. Experimental results are presented to verify theoretical discussion. This preposed inverter will be able to be prastically used as a power supply in various fields as induction, heating application, DC-DC converter etc.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.8
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• pp.689-696
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• 2001

Large-scale Multi-disciplinary Systems(LMS) such as transportation, aerospace, defense etc. are complex systems in which there are many subsystems, interfaces, functions and demanding performance requirements. Because many contractors participate in the development, it is necessary to apply methods of sharing common objectives and communicating design status effectively among all of the stakeholders. The processes and methods of systems engineering which includes system requirement analysis; functional analysis; architecting; system analysis; interface control; and system specification development provide a success-oriented disciplined approach to the project. This paper shows not only the methodology and the results of model-based systems engineering to Automated Guided Transit(AGT) system as one of LMS systems, but also propose the extension of the model-based tool to help manage a project by linking WBS (Work Breakdown Structure), work organization, and PBS (Product Breakdown Structure). In performing the model-based functional analysis, the focus was on the operation concept of an example rail system at the top-level and the propulsion/braking function, a key function of the modern automated rail system. The model-based behavior analysis approach that applies a discrete-event simulation method facilitates the system functional definition and the test and verification activities. The first application of computer-aided tool, RDD-100, in the railway industry demonstrates the capability to model product design knowledge and decisions concerning key issues such as the rationale for architecting the top-level system. The model-based product design knowledge will be essential in integrating the follow-on life-cycle phase activities. production through operation and support, over the life of the AGT system. Additionally, when a new generation train system is required, the reuse of the model-based database can increase the system design productivity and effectiveness significantly.

• Journal of the Korea Institute of Building Construction
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• v.14 no.5
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• pp.379-388
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• 2014

The purpose of this study is to investigate the effect of capsulated slurry phase change material (PCM) on the thermal crack in mass concrete by experimental work and FEM analysis. In this study, three conditions of samples were prepared for evaluating the level of hydration heat, i.e., a material condition, a cement paste condition and a concrete condition. Also, a compressive strength test was conducted for FEM inverse analysis. Based on the results of the experiment, exothermic function coefficients of concrete with encapsulated slurry PCM were deducted by the inverse analysis. After that, they applied to FEM analysis of the mass scale concrete structures. From the results of this experiment, $31^{\circ}C$ capsulated slurry PCM had no super cooling phenomenon in the material condition. In the cement condition, hydration heat decreased by 34.61J when PCM of 1g was mixed. In the concrete condition, PCM of 6% was deducted as the best level in hydration heat absorption. In FEM inverse analysis, rate coefficient of reaction gradually decreased when PCM mixing ratio increased. But, temperature-rise coefficient increased when PCM mixing ratio exceeded 6%. For the inversed exothermic function coefficients applying to large scale concrete structures, a thermal cracking index increased by 0.05 when PCM of 1% was mixed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.549-556
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• 2017

This study investigated the importance of social cognitive intervention and the cognitive rehabilitation intervention by comparing the difference and examining the relationship between neurological cognitive function and social cognitive function of stroke patients in the acute phase and chronic stroke before returning to the community. LOTCA, cartoon intention inference task, and social behavior sequence task were performed on 30 acute stroke inpatients and 30 chronic stroke patients from May 2015 to June 2016. A two sample t test was conducted to examine the differences between the groups. The Pearson's correlations test was performed to examine the correlation among the variables in each group. As a result, there were statistically significant differences between the neurological cognitive function and social cognitive function of acute stroke patients and chronic stroke patients who were undergoing rehabilitation training before returning to the community (p<0.05). A linear relationship was found between the thinking operation and social behavior sequence task in the acute stroke group (r=0.539, p<0.05). In the chronic stroke group, visual perception (r=0.530, p<0.05), visual motor organization (r=0.655, p<0.05) and thinking operation (r=0.534, p<0.05) were correlated with the cartoon intention inference task. In addition, the social behavior sequence task were correlated with visual organization (r=0.534, p<0.05) and thinking operation (r=0.764, p<0.05). As a result of multiple regression analysis, the neurological cognitive functions influencing the social cognitive function in the cartoon task was found to be the thinking operation (B = 0.431) in acute stroke patients and the thinking operation (B=0.272) and visuomotor organization (B = 0.218) in the case of chronic stroke. In addition, the results of the social behavior sequence task revealed the thinking operation (B=0.417) in the acute stroke patients, and thinking operation (B=0.267), visual motor organization(B=0.274) and visual perception(B=151) in chronic stroke patients to be significant. According to this result, there is a difference in the neurological and social cognitive levels between the two groups. Therefore, the social cognition is strongly related to the high level cognitive function as thinking operation of the neurological cognitive function. Therefore, in further research, it would be necessary to determine if there is a change in higher cognitive function in neurological cognitive function after applying a social cognition intervention program for stroke.

• Journal of Industrial Technology
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• v.25 no.B
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• pp.203-210
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• 2005

The PWM(Pulse Width Modulated) converter for the AC to DC rectification has become attractive in the industrial variable-speed drive application and the electric utilities due to the following benefits: Nearly the sinusoidal input current with unity power factor; Controllable DC link voltage; Bidirectional power flow. This paper presents a quantitative analysis of single and three phase PWM converter's input and output characteristics as a function of the input filter inductance under balanced and unbalanced conditions. Also, its performance under the supply voltage including harmonics is investigated by simulation with Matlab Simlulink and experiments. These results provide a reference for selecting the reasonable converter's input filter inductance for given harmonics or power factor criterion.

• Journal of Industrial Technology
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• v.25 no.B
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• pp.195-202
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• 2005

The rectifier characteristics and the quality of the input current worsens with the increase of unbalances or harmonics of the supply voltages. Rectifier input current harmonics interfere with proper power system operation, reduce rectifier power factor, and limit the power available from a given source. It is of importance to select appropriately the rectifier's output filter inductance to determine the rectifier input current waveform, the input current harmonics, and the power factor. This paper presents a quantitative analysis of single and three phase rectifier input current harmonics, total harmonic distortion, and power factor as a function of the output filter inductance under balanced and unbalanced conditions. Also, its performance under the supply voltage including harmonics be investigated. These results provide a reference for selecting reasonable rectifier's output filter inductance for given harmonics or power factor criterion.

• Proceedings of the KIEE Conference
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• 2006.04b
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• pp.197-199
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• 2006

This paper presents a analytical field solutions for the general class of Linear Brushless DC(LBLDC) motors with PM mover and 3-phase winding stator. In our magnetic field analysis, we have adopted an approach which can treat both magnetized material and winding from the each field analysis by magnetic vector potential considering 2-Dimensional slot modeling. Therefore, we give accurate analytical formulas and object function for design and parameters estimation by its magnetic field.