• Nuclear Engineering and Technology
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• v.54 no.8
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• pp.3166-3175
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• 2022

The most numerical investigations of the thermal-hydraulic phenomena following the loss of the residual heat removal capability during the mid-loop operation of the pressurized water reactor were performed according to simplifications and are not sufficiently accurate. To perform more accurate and more reliable predictions of thermal-hydraulic accidents in a nuclear power plant using computational fluid dynamics codes, a more detailed methodology is needed. Modelling results identified that thermal stratification and natural convection are observed. Temperatures of lower monitoring points remain low, while temperatures of upper monitoring points increase over time. The water in the heated region, in the upper unheated region and the pipe region was well mixed due to natural convection, meanwhile, there is no natural convection in the lower unheated region. Water temperature in the pipe region increased after a certain time delay due to circulation of flow induced by natural convection in the heated and upper unheated regions. The modelling results correspond to the experimental data. The developed computational fluid dynamics methodology could be applied for modelling of two-component single/two-phase natural convection and thermal stratification phenomena during the mid-loop operation of the pressurized water reactor or other nuclear and non-nuclear installations at similar conditions.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.8
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• pp.1083-1090
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• 1998

A kind of three-way check valve, so called hydraulic calve was proposed for the substitute of the density lock of passive reactor such as SPWR (System-Integrated Pressurized Water Reactor). The function of the valve are the separation of the borated water from main coolant loop for normal operation and the insurge of the water into the loop for shutdown and the removal of the decay power when the main coolant flow rate is not enough. To verify the operability and the characteristics of the valve, experimental works were executed with 1/3 scale model calve. Also a diffuser model was proposed for the theoretical analysis of the valve.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05b
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• pp.23-28
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• 1996

The potential for the RELAP5/MOD3.2 was assessed for the loss-of-RHR event during the mid-loop operation and the predictability of major thermal-hydraulic phenomena was also evaluated for the long term transient. The analysis results of the typical two cases(cold leg opening case and pressurizer opening case) were compared with experimental data which was conducted at ROSA-IV/LSTF in Japan. As a result, it was shown that tile code was capable of simulating the thermal-hydraulic transport process with appropriate time step during the reduced inventory operation with the loss-of- RHR system.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.359-360
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• 2002

A bacterial strain able to degrade terephthalic acid (TPA) was isolated and identified to belong to the Corynebacterium sp. It was named Corynebacterium sp. YT-14. When stirred loop bioreactor was used in a batch type system for removing terephthalic acid from weight loss treatment wastewater and complex dyeing process wastwater, the removal efficiency of terephthalic acid was 85.4% after 7 days of treatment of the weight loss treatment wastewater, while no residual terephthalic acid was detected after 3 days of treatment of the complex dyeing process wastewater

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05b
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• pp.745-750
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• 1996

An analysis of a loss of residual heat removal system (RHRS) event during midloop operation after reactor shutdown was performed using the RELAP5/MOD3 thermal-hydraulic computer code. The experimental data of a 5% cold leg break test conducted at the ROSA-IV Large Scale Test Facility (LSTF) to simulate a main coolant pump shaft seal removal event during midloop operation of a Westinghouse-type PWR were used in the analysis. The predicted core boiling time and the peak primary system pressure showed good agreements with the measured data. Some differences between the calculational results and the experimental results were, however, found in areas of the timing of loop seal clearing and the temperature distribution in a pressurizer. Other calculational problems identified were discussed as well.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.236-241
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• 1988

This note considers the class of controllers with integral action which arise directly from appropriate system models. Via internal model principle approach, a corresponding class of self-tuning controller is shown to have both integral action in controller and offset removal in the tuning algorithm. The key idea is to constrain the estimator in each step in order to ensure that dc gain of feedforward and feedback polynomial of adaptive controller are always equal, thus allowing the loop integrator to work properly.

• Nuclear Engineering and Technology
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• v.49 no.8
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• pp.1617-1628
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• 2017

In the passive residual heat removal system of a molten salt reactor, one of the residual heat removal methods is to use the thimble-type heat transfer elements of the drain salt tank to remove the residual heat of fuel salts. An experimental loop is designed and built with a single heat transfer element to analyze the heat transfer and flow characteristics. In this research, the influence of the size of a three-layer thimble-type heat transfer element on the heat transfer rate is analyzed. Two methods are used to obtain the heat transfer rate, and a difference of results between methods is approximately 5%. The gas gap width between the thimble and the bayonet has a large effect on the heat transfer rate. As the gas gap width increases from 1.0 mm to 11.0 mm, the heat transfer rate decreases from 5.2 kW to 1.6 kW. In addition, a natural circulation startup process is described in this paper. Finally, flashing natural circulation instability has been observed in this thimble-type heat transfer element.

• Nuclear Engineering and Technology
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• v.52 no.5
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• pp.964-974
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• 2020

The small modular reactors (SMRs) of the integrated pressurized water reactor (IPWR) type have been widely developed owing to their enhanced safety features. The SMR-IPWR adopts passive residual heat removal system (PRHRS) to extract residual heat from the core. Because the PRHRS removes the residual heat using the latent heat of the water stored in the emergency cooldown tank, the PRHRS gradually loses its cooling capacity after the stored water is depleted. A quick restoration of the power supply is expected infeasible under station blackout accident condition, so an advanced PRHRS is needed to ensure an extended grace period. In this study, an advanced design is proposed to indirectly incorporate a dry air cooling tower to the PRHRS through an intermediate loop called indefinite PRHRS. The feasibility of the indefinite PRHRS was assessed through a long-term transient simulation using the MARS-KS code. The indefinite PRHRS is expected to remove the residual heat without depleting the stored water. The effect of the environmental temperature on the indefinite PRHRS was confirmed by parametric analysis using comparative simulations with different environmental temperatures.

• Archives of Plastic Surgery
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• v.36 no.4
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• pp.512-515
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• 2009

Purpose: Neurofibromatosis(NF) is an autosomal - dominant systemic disease. Up to fifty percent of patients with NF are reported to have concomitant vascular abnormalities. In the resection of a larger NF, the risk of uncontrolled hemorrhage is much higher due to the difficulty of hemostasis of large vessels within the tumor. We ligated the base of the giant NF with a simple loop - shaped ligation before removal of the giant NF in both buttocks. And then we could successfully reduce the amount of hemorrhage during the operation. Methods: A 46 - year - old female patient presented for giant masses of both gluteal area, which has been growing slowly for the last ten years. Each mass was about $30{\times}20cm$ in size. After designing the elliptical resection margin, we tightened the tumor base by using continuous loop - shaped suture ligation(weaving the thread up and down in a loop - shaped pattern, leaving a space of 2 cm between each loop) with a straight needle and prolene 2 - 0. After skin incision, we proceeded the dissection toward the central and inferior side of the mass obliquely while we avoided breaking large vascular sinuses. We resected the tumor in a wedged - shape. Subcutaneous tissue was sutured layer by layer and skin was closed by vertical mattress and interrupted suture. The loop - shaped ligation of the base was removed and compressive dressing was done with gauzes and elastic bandages. Results: Postoperative complications such as infection, hemorrhage, hematoma, and dehiscense did not occur. Perioperatively the patient was sufficiently transfused with five units of blood and two units of fresh frozen plasma. During the subsequent 1 year follow - up, the functional and cosmetic result was excellent. Conclusion: A continuous loop - shaped suture ligation procedure along the base of the giant NF effectively reduced the amount of hemorrhage during the operation, made dissection and ligation of vessels easily and quickly, and shorten the operating time and postoperative recovery time.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.6
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• pp.825-831
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• 2016

In this paper, a transimpedance amplifier based on a new DC offset cancellation (DCOC) method is proposed for WCDMA/LTE applications. The proposed method applies a sample and hold mechanism to the conventional DCOC method with a DC feedback loop. It prevents the removal of information around the DC, so it avoids signal-to-noise ratio degradation. It also reduces area and power consumption. It was designed in a $0.13{\mu}m$ deep n-well CMOS technology and drew a maximum current of 1.58 mA from a 1.2 V supply voltage. It showed a transimpedance gain of $80dB{\Omega}$, an input-referred noise current lower than 0.9 pA/${\surd}$Hz, an out-of-band input-referred 3rd-order intercept point more than 9.5 dBm, and an output DC offset lower than 10 mV. Its area is $0.46mm{\times}0.48mm$.