• Nuclear Engineering and Technology
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• v.48 no.6
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• pp.1349-1359
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• 2016

Alternative control schemes for an Advanced High Temperature Reactor system consisting of a reactor, an intermediate heat exchanger, and a secondary heat exchanger (SHX) are presented in this paper. One scheme is designed to control the cold outlet temperature of the SHX ($T_{co}$) and the hot outlet temperature of the intermediate heat exchanger ($T_{ho2}$) by manipulating the hot-side flow rates of the heat exchangers ($F_h/F_{h2}$) responding to the flow rate and temperature disturbances. The flow rate disturbances typically require a larger manipulation of the flow rates than temperature disturbances. An alternate strategy examines the control of the cold outlet temperature of the SHX ($T_{co}$) only, since this temperature provides the driving force for energy production in the power conversion unit or the process application. The control can be achieved by three options: (1) flow rate manipulation; (2) reactor power manipulation; or (3) a combination of the two. The first option has a quicker response but requires a large flow rate change. The second option is the slowest but does not involve any change in the flow rates of streams. The third option appears preferable as it has an intermediate response time and requires only a minimal flow rate change.

• International Journal of Air-Conditioning and Refrigeration
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• v.16 no.3
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• pp.77-82
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• 2008

For heat pumps used in a cold region, it is very important to obtain appropriate heating capacity. Several studies using a variable speed compressor and an additional heater have been performed to enhance heating capacity at low ambient temperatures. However, for outdoor temperature conditions below $-15^{\circ}C$, it is still difficult to obtain enough heating capacity above the rated value. In recent studies, the application of gas injection technique into a two-stage heat pump yielded noticeable heating performance improvement at low temperature conditions. In this study, the heating performance of a two-stage gas injection heat pump with a rated capacity of 3.5 kW was measured and analyzed by varying refrigerant charge amount and EEV opening at the standard heating condition. The heating performance of the two-stage gas injection heat pump was compared with that of a two-stage non-injection heat pump. The heating capacity and COP of the two-stage gas injection heat pump were improved by 2-10% at the optimal charging condition over those of the two-stage non-injection heat pump.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.1001-1004
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• 2008

This study reviewed the results of utilization of insulation heat curing method using double layer bubble sheet in slab concrete and mass concrete in cold weather environment. First of all, when double layer bubble sheets are applied, it was shown that slab concrete was protected from early freezing by remaining between 6 and $10^{\circ}C$ even in case outside temperature drops $10^{\circ}C$ below zero until the 2nd day from piling, and in the case of mass concrete, with the maximum temperature difference between the center and surface less than $6^{\circ}C$, crack occurrence index was close to 2 and no hydration heat crack occurred by internal constraint. The insulation heat preservation curing method using the double bubble sheet applied in this field prevented early freezing owing to stable curing temperature management, deterring concrete strength development delay at low temperature, and obtained the needed strength. Also, it was proven that the method is highly effective and economic for cold weather concrete quality maintenance through curing cost reduction like construction period shortening and labor cost reduction, etc by reducing the process of temporary equipment installation and disassembling.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.748-753
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• 2011

Generally, in the temperature and environment test of railway electronics, cold and heat resistant tests are involved. Relevant KRS standards describe "There is no problem" as acceptance criteria for function check during the temperature and environment tests. According to this requirement, testers perform some function and performance tests which are easy to perform during test procedure using temperature chamber. This paper reviews the limit of current check method for cold and heat resistant tests and proposes an alternative. An alternative is the application of data sheet. Using data sheet, the temperature of equipped components is checked whether this temperature meet acceptance criteria or not. Also, this paper suggests temperature test range guidelines comparing temperature standards for general IC component. For the example in real field, this method uses the lowest temperature and the highest temperature in major domestic cities.

• Journal of Powder Materials
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• v.14 no.1 s.60
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• pp.13-18
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• 2007

The mother Ni-W (1-5 wt.%) alloy billets for coated conductor substrate were fabricated by powder metallurgy process. The tensile test results for the sintered Ni-W rods showed the increase of mechanical strength and decrease of ductility with increasing W content due to the solid solution hardening. All the fracture surfaces of the tested specimens showed the typical ductile fracture mode of dimple rupture due to the local necking. The Ni-W alloy billets were made into tape by cold rolling. After the appropriate heat treatment for recrystallization, the brass texture formed by the cold rolling was converted to the complete cube texture. The in-plane and out of plane texture of the tapes estimated by x-ray pole figure were smaller than 9 degree and 7 degree, respectively. The effect of the W addition on the texture development seems not to be significant.

• Korean Journal of Oriental Medicine
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• v.2 no.1
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• pp.454-484
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• 1996

There are many factors to evoke pain, for example cold, heat, seven emotion, digestion, fatigue, venemous worms, deficiency of blood etc., and its pathogenesis is complicated. Treatments for pain in oriental medicine are as follows. 1. Pharmacotherapy is a method to treat pain by different effects of herbal medicine, for example, regulating vital energy, activating blood circulation, eliminating phlegm, and dispelling the cold evil etc. 2. Acupuncture and moxibustion therapy is a kind of external application, it has a distinct effect in relieving pain. Recently its operation method has been more developed, so new acupuncture therapies are used in clinics. There are electroacupuncture, auricular acupuncture and injection of drugs at an acupuncture points etc. 3. Oriental physiotherapy is a treatment method to stimulate acupuncture points and meridians. (1) Hot pack, Paraffin bath, Microwave, Ultrasound, Short wave, Infra-red etc. are used to treat cold syndrome by dispersing cold by warming the channels. (2) E.S.T., I.C.T., T.E.N.S., S.S.P., cupping treatment etc. are used to treat disorders of vital energy. (3) Health ion, Carbon, T.D.P., etc are used to treat conic and deficiency syndrome.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.88.1-88.1
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• 2010

In recent days, the study for the renewable energy is required to supplement traditional energy source. One of the renewable energy of Fuel Cell is classified according to the electrolytes. It is the MCFC (Molten Carbonate Fuel Cell) for this study. One of the equipments of the heat exchangers is important component for efficiency and cost. In MCFC system, several heat exchangers are used according to the application. It is named for the humidifier because it is to preheat the fuel and water so that a reactor will convert some of the incoming fuel to hydrogen. Then, hot side fluid service is used the exhausted gas from the fuel cell and cold side fluid service is the fuel and water. The operation temperature range is about 25~500 Celsius Degree. This heat exchanger has the problems of heat transfer considering to multiphase fluid and phase changing. So it is necessary to analyze the heat transfer characteristics and to propose the reasonable design methodology for the humidifier. In this study, the thermal characteristic for the humidifier is estimated by using commercial tool of heat exchanger design and rating. And this study provides the testing methodology and presents the results for test facility of fabrication and for testing.

• Journal of Korean Society of Steel Construction
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• v.23 no.4
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• pp.483-491
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• 2011

The fabrication of steel structural members always involves welding process such as flux cored arc welding. Therefore, for the application of structural steels to cold regions, it is a prerequisite to clarify the service temperature of the welded joints in order to ensure the structural integrity of the welded parts. In this study, the Charpy impact test was conducted to evaluate the service temperature of structural steel weld. The Charpy impact test is a commercial quality control test for steels and other alloys used in the construction of metallic structures. The test allows the material properties for service conditions to be determined experimentally in a simple manner with a very low cost. Standard V-notch Charpy specimens were prepared and tested under dynamic loading condition. The service temperatures of the weld metal, HAZ (heat affected zone) and base metal were derived by the absorbed energy and the impact test requirements; thus the applicability of the structural steels to cold regions was discussed in detail.

• Journal of Sasang Constitutional Medicine
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• v.9 no.1
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• pp.25-101
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• 1997

The physiologic and pathologic theories of "The Yellow Emperor's Canon of Internal Medicine (黃帝內經)" were based on yin-yang theory. It has been an important constituent of traditional Chinese medicine, and the eight principal syndromes have been main guidelines in diagnosis and treatment. Recently it had an great influene on the formation of the pathophysiology of Constitutional medicine. Therefore each constitution menifests special pathophysiologic propriorities of the eight pricipal syndromes, especially specific to one's constitution. So we can recognize specific patterns of the yin and yang, cold and heat, exterior and interior, deficient and excessive syndromes through a series of processes distinguishing one's constitution. The theory of the Constitutional medicine, however, has contained those achievements in a new angle and view the problem from a little different standpoint. The dynamic relationships inevitably have caused certain changes and distortions in the meaning and application of eight principles. These are a progress in medical science, and this advance is the stirring venture of Lee jaema. This thesis has intended to show the delicate relationship between the two, and investigate into these "changes and distortions".

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.2
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• pp.276-287
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• 1990

In this paper research result of transient thermal stress analysis of power plant turbine rotors for life prediction under severs operating conditions is presented. Galerkin's recurrence scheme is used for numerical solution of discretized FEM equation of transient heat conduction equation. Boundary conditions for the equation and operating conditions are intensively investigated for accurate life prediction of turbine rotors in operation. A computer program for on-site application is developed and tested. Distribution of thermal stress in turbine rotors during various operating condition is analyzed with the program and it is found that the peak thermal stress appears during cold stage conditions at the first stage of high pressure rotors.