ANALYSES OF ANNULAR LINEAR INDUCTION PUMP CHARACTERISTICS USING A TIME-HARMONIC FINITE DIFFERENCE ANALYSIS

성승환,김성오 한국원자력학회 2008 Nuclear Engineering and Technology Vol.40 No.3

The pumping of coolant in a liquid metal fast reactor may be performed with an annular linear induction electro-magnetic (EM) pump. Linear induction pumps use a traveling magnetic field wave created by poly-phase currents, and the induced currents and their associated magnetic field generate a Lorentz force, whose effect can be the pumping of the liquid metal. The flow behaviors in the pump are very complex, including a time-varying Lorentz force and pressure pulsation, because an induction EM pump has time-varying magnetic fields and the induced convective currents that originate from the flow of the liquid metal. These phenomena lead to an instability problem in the pump arising from the changes of the generated Lorentz forces along the pump’s geometry. Therefore, a magneto-hydro-dynamics (MHD) analysis is required for the design and operation of a linear induction EM pump. We have developed a time-harmonic 2-dimensional axisymmetry MHD analysis method based on the Maxwell equations. This paper describes the analysis and numerical method for obtaining solutions for some MHD parameters in an induction EM pump. Experimental test results obtained from an induction EM pump of CLIP-150 at the STC “Sintez,” D.V. Efremov Institute of Electro-physical Apparatus in St. Petersburg were used to validate the method. In addition, we investigated some characteristics of a linear induction EM pump, such as the effect of the convective current and the double supply frequency (DSF) pressure pulsation. This simple model overestimated the convective eddy current generated from the sodium flow in the pump channel; however, it had a similar tendency for the measured data of the pump performance through a comparison with the experimental data. Considering its simplicity, it could be a base model for designing an EM pump and for evaluating the MHD flow in an EM pump.

건축과 법률이야기 - 구분소유권의 인정 요건

성승환,Seong, Seung-Hwan 대한건축사협회 2013 建築士 Vol.2013 No.3

건축과 법률이야기 - 관리처분계획 무효확인소송의 소의 이익

성승환,Seong, Seung-Hwan 대한건축사협회 2013 建築士 Vol.2013 No.11

안타까움, 불안·공포·허무함

성승환 (사)방송기자연합회 2011 방송기자 Vol.5 No.-

건축과 법률이야기 - 온타임 옵션제 이행을 위한 설명 의무

성승환,Seong, Seung-hwan 대한건축사협회 2014 建築士 Vol.2014 No.3

Factor Structure of the Hamilton Depression Rating Scale for Patients with Major Depression with the Anxious Distress Specifier in DSM-5

성승환,우영섭,박원명 대한우울조울병학회 2019 우울조울병 Vol.17 No.1

Background: The factor structure of the Hamilton Depression Rating Scale (HDRS) is well validated for patients with major depressive disorder (MDD). We examined whether HDRS factors can measure the anxious distress specifier in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, in patients with MDD. Methods: A retrospective chart review of patients with MDD between March 2012 and June 2015 was conducted. We extracted data on anxious distress symptoms and detailed clinical information and examined how the 5 HDRS factors (anhedonia/retardation, guilt/agitation, bodily symptoms, insomnia, and appetite) were related to the anxious distress specifier using the receiver operating characteristic (ROC) curve analysis and the area under the ROC curve analysis. Results: We observed significant differences in the HDRS and Beck Depression Inventory scores between anxious distress and non-anxious distress groups at the index episode. The score for guilt/agitation factor was significantly higher than that for other factors in the anxious distress group and exhibited good predictive efficiency at baseline. Conclusion: Further investigation of the anxious distress specifier as a diagnostic entity would be worthwhile. In addition, the scores for guilt/agitation factor on the HDRS might be a promising marker for distinguishing patients with anxious distress from those with other subtypes of major depression, especially for the index episode.

근거중심 한국형 우울증 약물학적 치료지침, 개정판(II) : 항우울제의 위약대비 효과, 항우울제간 효과차이 및 효과판정의 적정시점

성승환,한상우,박용천,박선철,한규만,원은수,이화영,구재우,백종우,이경민,전홍진,이문수,심세훈,고영훈,이강준,한창수,함병주,최준호,황태연,오강섭,이민수 대한신경정신의학회 2013 신경정신의학 Vol.52 No.5

Objectives The purpose of this study was to suggest recommendations of antidepressant efficacy compared with placebo, difference in efficacy of antidepressants, and appropriate time of efficacy judgment in antidepressant therapy. Methods Using recommendations from 12 international and domestic clinical practice guidelines for depression, drawing of recommendation drafts, and peer review, the executive committee developed the guideline. Results Tricyclic antidepressants (TCAs), monoamine oxidase inhibitors (MAOI), selective serotonin reuptake inhibitors (SSRI), serotonin and norepinephrine reuptake inhibitors (SNRIs), norepinephrine and specific serotonergic antidepressants (NaSSAs), norepinephrine and dopamine reuptake inhibitors (NDRIs), and serotonin antagonist and reuptake inhibitors (SARIs) were strongly recommended as having antidepressant efficacy compared with placebo. Difference in efficacy of antidepressants was as follows. TCAs, MAOI, SSRI, SNRIs, and NaSSAs were strongly recommended, however, NDRIs, SARIs were weakly recommended. If there was no or minimal improvement with treatment, appropriate time of efficacy judgment in antidepressant therapy was estimated to be after two to four weeks. Conclusion We hope that the results of this study will be helpful in encouraging the optimal treatment by understanding antidepressant efficacy compared with placebo, difference in efficacy of antidepressants, and appropriate time of efficacy judgment in antidepressant therapy.

ESTABLISHMENT OF A NEURAL NETWORK MODEL FOR DETECTING A PARTIAL FLOW BLOCKAGE IN AN ASSEMBLY OF A LIQUID METAL REACTOR

성승환,HAE-YONG JEONG,허섭,김성오 한국원자력학회 2007 Nuclear Engineering and Technology Vol.39 No.1

A partial flow blockage in an assembly of a liquid metal reactor could result in a cooling deficiency of the core. To develop a partial blockage detection system, we have studied the changes of the temperature fluctuation characteristics in the upper plenum according to changes of the flow blockage conditions in an assembly. We analyzed the temperature fluctuation in the upper plenum with the Large Eddy Simulation (LES) turbulence model in the CFX code and evaluated its statistical parameters. Based on the results of the statistical analyses, we developed a neural network model for detecting a partial flow blockage in an assembly. The neural network model can retrieve the size and the location of a flow blockage in an assembly from a change of the root mean square, the standard deviation, and the skewness in the temperature fluctuation data. The neural network model was found to be a possible alternative by which to identify a flow blockage in an assembly of a liquid metal reactor through learning and validating various flow blockage conditions.

Development of a Simplified Model for Analyzing the Performance of KALIMER-600 Coupled with a Supercritical Carbon Dioxide Brayton Energy Conversion Cycle

성승환,이태호,김성오 한국원자력학회 2009 Nuclear Engineering and Technology Vol.41 No.6

A KALIMER-600 concept which is a type of sodium-cooled fast reactor, has been developed at KAERI. It uses sodium as a primary coolant and is a pool-type reactor to enhance safety. Also, a supercritical carbon dioxide (CO₂) Brayton cycle is considered as an alternative to an energy conversion system to eliminate the sodium water reaction and to improve efficiency. In this study, a simplified model for analyzing the thermodynamic performance of the KALIMER-600 coupled with a supercritical CO₂ Brayton cycle was developed. To develop the analysis model, a commercial modular modeling system (MMS) was adopted as a base engine, which was developed by nHance Technology in USA. It has a convenient graphical user interface and many component modules to model the plant. A new user library for thermodynamic properties of sodium and supercritical CO₂ was developed and attached to the MMS. In addition, some component modules in the MMS were modified to be appropriate for analysis of the KALIMER-600 coupled with the supercritical CO₂ cycle. Then, a simplified performance analysis code was developed by modeling the KALIMER-600 plant with the modified MMS. After evaluating the developed code with each component data and a steady state of the plant, a simple power reduction and recovery event was evaluated. The results showed an achievable capability for a performance analysis code. The developed code will be used to develop the operational strategy and some control logics for the operation of the KALIMER-600 with a supercritical CO₂ Brayton cycle after further studies of analyzing various operational events.

DEVELOPMENT OF REACTOR POWER CONTROL LOGIC FOR THE POWER MANEUVERING OF KALIMER-600

성승환,강한옥,김성오 한국원자력학회 2010 Nuclear Engineering and Technology Vol.42 No.3

We developed an achievable control logic for the reactor power level during a power maneuvering event and set up some constraints for the control of the reactor power in a conceptual sodium-cooled fast reactor (KALIMER-600) that was developed at KAERI. For simulating the dynamic behaviors of the plant, we developed a fast-running performance analysis code. Through various simulations of the power maneuvering event, we evaluated some suggested control logic for the reactor power and found an achievable control logic. The objective of the control logic is to search for the position of the control rods that would keep the average temperature of the primary pool constant and, concurrently, minimize the power deviation between the reactor and the BOP cycle during the power maneuvering. In addition, the flow rates of the primary pool and the intermediate loop should be changed according to the power level in order to not violate the constraints set up in this study. Also, we evaluated some movement speeds of the control rods and found that a fast movement of the control rods might cause the power to fluctuate during the power maneuvering event. We suggested a reasonable movement speed of the control rods for the developed control logic.