• Nuclear Engineering and Technology
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• v.56 no.3
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• pp.803-811
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• 2024

Nuclear accidents such as Fukushima Daiichi have highlighted the potential of passive safety systems to replace or complement active safety systems as part of the overall prevention and/or mitigation strategies. In addition, passive systems are key features of Small Modular Reactors (SMRs), for which they are becoming almost unavoidable and are part of the basic design of many reactors available in today's nuclear market. Nevertheless, their potential to significantly increase the safety of nuclear power plants still needs to be strengthened, in particular the ability of computer codes to determine their performance and reliability in industrial applications and support the safety demonstration. The PASTELS project (September 2020-February 2024), funded by the European Commission "Euratom H2020" programme, is devoted to the study of passive systems relying on natural circulation. The project focuses on two types, namely the SAfety COndenser (SACO) for the evacuation of the core residual power and the Containment Wall Condenser (CWC) for the reduction of heat and pressure in the containment vessel in case of accident. A specific design for each of these systems is being investigated in the project. Firstly, a straight vertical pool type of SACO has been implemented on the Framatome's PKL loop at Erlangen. It represents a tube bundle type heat exchanger that transfers heat from the secondary circuit to the water pool in which it is immersed by condensing the vapour generated in the steam generator. Secondly, the project relies on the CWC installed on the PASI test loop at LUT University in Finland. This facility reproduces the thermal-hydraulic behaviour of a Passive Containment Cooling System (PCCS) mainly composed of a CWC, a heat exchanger in the containment vessel connected to a water tank at atmospheric pressure outside the vessel which represents the ultimate heat sink. Several activities are carried out within the framework of the project. Different tests are conducted on these integral test facilities to produce new and relevant experimental data allowing to better characterize the physical behaviours and the performances of these systems for various thermo-hydraulic conditions. These test programmes are simulated by different codes acting at different scales, mainly system and CFD codes. New "system/CFD" coupling approaches are also considered to evaluate their potential to benefit both from the accuracy of CFD in regions where local 3D effects are dominant and system codes whose computational speed, robustness and general level of physical validation are particularly appreciated in industrial studies. In parallel, the project includes the study of single and two-phase natural circulation loops through a bibliographical study and the simulations of the PERSEO and HERO-2 experimental facilities. After a synthetic presentation of the project and its objectives, this article provides the reader with findings related to the physical analysis of the test results obtained on the PKL and PASI installations as well an overall evaluation of the capability of the different numerical tools to simulate passive systems.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.7
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• pp.380-394
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• 2015

This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2014. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of heat and mass transfer, cooling and heating, and air-conditioning, the flow inside building rooms, and smoke control on fire. Research issues dealing with duct and pipe were reduced, but flows inside building rooms, and smoke controls were newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for thermal contact resistance measurement of metal interface, a fan coil with an oval-type heat exchanger, fouling characteristics of plate heat exchangers, effect of rib pitch in a two wall divergent channel, semi-empirical analysis in vertical mesoscale tubes, an integrated drying machine, microscale surface wrinkles, brazed plate heat exchangers, numerical analysis in printed circuit heat exchanger. In the area of pool boiling and condensing, non-uniform air flow, PCM applied thermal storage wall system, a new wavy cylindrical shape capsule, and HFC32/HFC152a mixtures on enhanced tubes, were actively studied. In the area of industrial heat exchangers, researches on solar water storage tank, effective design on the inserting part of refrigerator door gasket, impact of different boundary conditions in generating g-function, various construction of SCW type ground heat exchanger and a heat pump for closed cooling water heat recovery were performed. (3) In the field of refrigeration, various studies were carried out in the categories of refrigeration cycle, alternative refrigeration and modelling and controls including energy recoveries from industrial boilers and vehicles, improvement of dehumidification systems, novel defrost systems, fault diagnosis and optimum controls for heat pump systems. It is particularly notable that a substantial number of studies were dedicated for the development of air-conditioning and power recovery systems for electric vehicles in this year. (4) In building mechanical system research fields, seventeen studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, and renewable energies, piping in the buildings. Proposed designs, performance performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the evaluation of work noise in tunnel construction and the simulation and development of a light-shelf system. The subjects of building energy were worked on the energy saving of office building applied with window blind and phase change material(PCM), a method of existing building energy simulation using energy audit data, the estimation of thermal consumption unit of apartment building and its case studies, dynamic window performance, a writing method of energy consumption report and energy estimation of apartment building using district heating system. The remained studies were related to the improvement of architectural engineering education system for plant engineering industry, estimating cooling and heating degree days for variable base temperature, a prediction method of underground temperature, the comfort control algorithm of car air conditioner, the smoke control performance evaluation of high-rise building, evaluation of thermal energy systems of bio safety laboratory and a development of measuring device of solar heat gain coefficient of fenestration system.

• The Korean Journal of Pesticide Science
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• v.2 no.3
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• pp.107-116
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• 1998

Based on the differential growth response to exogenous gibberellic acid ($GA_{3}$) between semi-dwarf wheat(Triticum aestivum) and wild oat(Avena fatua), we examined the possibility of improving the selective performance of several herbicides by $GA_{3}$ application and the physiological background of $GA_{3}$-induced increase in herbicidal activity. Growth of wild oat was 4 to 5 times higher than that of wheat by $GA_{3}$ treatment. Pretreatment of wild oat seed with 300 ppm $GA_{3}$ increased the herbicidal activities of trifluralin and isoproturon by soil-surface application, but not of alachor and metsulfuron-methyl. $GA_{3}$ applied simultaneously with post-emergence herbicides resulted in a significant or moderate improvement of the efficacy of such herbicides as tralkoxydim, fenoxaprop-ethyl, metsulfuron-methyl, metribuzine and isoproturon, but not in the mixtures of oxyfluorfen or paraquat with $GA_{3}$. In the sequencial treatment of tralkoxydim and $GA_{3}$ at interval of one-day, $GA_{3}$ applied prior to tralkoxydim significantly increased a chlorosis and desiccation of leaf without affecting the growth inhibition by tralkoxydim. Tralkoxydim followed by $GA_{3}$ application had lower herbicidal activity than that of $GA_{3}$ followed by tralkoxydim treatment. Electrolyte leakage response of $GA_{3}$-pretreated or $GA_{3}$-untreated wild oat leaf against several compounds inducing membrane. peroxidation was compared. Differencial responses were observed in oxyfluorfen and isoproturon treatments with an increased electrolyte leakage in $GA_{3}$-pretreated tissue, but not in paraquat and rose bengal treatments. These results suggest that $GA_{3}$-induced increase in herbicidal activity is likely to be dependent on a herbicide type and may be due to activation of a metabolic ability related with herbicidal reponse as well as an increase in the herbicide absorbtion and translocation, rather than due to membrane and cell wall extention induced by $GA_{3}$, which in turn makes the herbicides easily enter.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.2
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• pp.194-201
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• 1995

In order to make clear the resistance of bag nets, the resistance R of bag nets with wall area S designed in pyramid shape was measured in a circulating water tank with control of flow velocity v and the coefficient k in $R=kSv^2$ was investigated. The coefficient k showed no change In the nets designed in regular pyramid shape when their mouths were attached alternately to the circular and square frames, because their shape in water became a circular cone in the circular frame and equal to the cone with the exception of the vicinity of frame in the square one. On the other hand, a net designed in right pyramid shape and then attached to a rectangular frame showed an elliptic cone with the exception of the vicinity of frame in water, but produced no significant difference in value of k in comparison with that making a circular cone in water. In the nets making a circular cone in water, k was higher in nets with larger d/l, ratio of diameter d to length I of bars, and decreased as the ratio S/S_m$ of S to the area $S_m$ of net mouth was increased or as the attack angle 9 of net to the water flow was decreased. But the value of ks15m was almost constant in the region of S/S_m=1-4$ or $\theta=15-90^{\circ}$ and in creased linearly in S/S_m>4 or in $\theta<15^{\circ}$ However, these variation of k could be summarized by the equation obtained in the previous paper. That is, the coefficient $k(kg\;\cdot\;sec^2/m^4)$ of bag nets was expressed as $$k=160R_e\;^{-01}(\frac{S_n}{S_m})^{1.2}\;(\frac{S_m}{S})^{1.6}$$ for the condition of $R_e<100$ and $$k=100(\frac{S_n}{S_m})^{1.2}\;(\frac{S_m}{S})^{1.6}$$ for $R_e\geq100$, where $S_n$ is their total area projected to the plane perpendicular to the water flow and $R_e$ the Reynolds' number on which the representative size was taken by the value of $\lambda$ defined as $$\lambda={\frac{\pi d^2}{21\;sin\;2\varphi}$$ where If is the angle between two adjacent bars, d the diameter of bars, and 21 the mesh size. Conclusively, it is clarified that the coefficient k obtained in the previous paper agrees with the experimental results for bag nets.

• Journal of Animal Environmental Science
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• v.14 no.1
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• pp.31-38
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• 2008

Ammonia gas is one of the malodorous gases from swine production facilities, such as manure storage tank, manure fermentation facilities, and livestock houses, etc. Ammonia gas from swine house is being emitted at relatively low concentrations throughout the year. Therefore, livestock facilities were continuously ventilated to supply fresh air for respiration of the animals internal the livestock facilities. The swine facilities need very high ventilation rate to control the inside environmental conditions. The deodorization system of the livestock facilities must be developed considering the ventilation rates. The odor abatement system was installed in order to improve the internal environment of the naturally ventilated growing-finishing pig house. The system which distributes the deodorized air into inner space of the swine house by using plastic duct was installed. Since the internal environment, effected by the operation of the odor abatement system, is monitored by closing the winch curtain installed on the side wall of the pig house, the experiment was practiced at the season when the internal environment becomes aggravated, winter. The effects on the improvement in the internal environment of swine house by operating the odor abatement system are as follows ; 1. By re-distributing the air which was deodorized by the odor abatement system installed in the pig house, the result showed that the concentration of ammonia gas is decreased approximately 33.3% compared with that before operating odor abatement system. 2. The effect on the pig house's ammonia gas reduction was found that the ventilation rate was less than $0.5m^3$/min head. The effect of the operation of the odor abatement system showed to be scarce when the ventilation rate increases because of the influx of external fresh air makes the quantity of diluted air more than those of the odor abatement system. 3. The perishment rate of the pigs which were brooded until slaughtering decreased about 3.8% by operating the odor abatement system in the growing-finishing pig house. Also, after operating the odor abatement system, the stinging of the eyes, suspension dust, etc were decreased when going into swine house for management.