• Korean Journal of Veterinary Research
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• v.33 no.3
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• pp.361-368
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• 1993

The midbrain periaqueductal gray is a midline structure that encircles the mesencephalic aqueduct of midbrain and plays an important role in anaglgesia and modulation of nociceptive input to the central nervous system. It has been demonstrated that the periaqueductal gray contains several neuropeptides including neurotensin, which has been postulated antinociceptive effect to the periaqueductal gray. The present study was performed to provide immunohistochemical localization of neurotensin of midbrain periaqueductal gray in the Korean native goat by using immunohistochemical method. Neurotensin-like immunireactive neurons were localized throughout the midbrain periaqueductal gray, although more immunoreactive neurons were present in the middle and caudal parts of periaquductal gray than the rostral part. Dense neurotensin-like immunoreactive neurons were much more numerous in the ventral lateral division of the mid- and caudal periaqueductal grays. Neurotensin-like immunoreactive neurons were much larger and more prominent near the external margin of the gray than in the juxta-aqueductal region. Neurotensin-like immunoreactive fibers were observed as short processes extending from immunoreactive cells and some small immunoreactive puncta and varicose-like fibers were also seen.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.2
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• pp.67-74
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• 2005

This paper concerns attitude controller design for a 3-staged launch vehicle which has movable nozzle TVC systems for all stages as its control systems. The PD-type control gains are determined by shaping the corresponding closed-loop natural frequencies for the purpose of guaranteeing the required stability margin. Bending filters are also designed to stabilize the bending modes by using parametric optimization method. The designed controllers are verified using six degree of freedom flight simulations in MATLAB.

• Journal of Energy Engineering
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• v.17 no.4
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• pp.198-203
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• 2008

The objective of the research was to study the effects of Miller cycle in a modified using diesel engine. The engine was dedicated to natural gas usage by modifying pistons, fuel system and ignition systems. The engine was installed on a dynamometer and attached with various sensors and controllers. Intake valve timing, engine speed, load, injection timing and ignition timing are main parameters. The results of engine performances and emissions are present in form of graphs. Miller Cycle without supercharging can increase brake thermal efficiency and reduce brake specific fuel consumption. The injection timing must be synchronous with valve timing, speed and load to control the performances, emissions and knock margin. Throughout these tested speeds, original camshaft is recommended to obtain high volumetric efficiency. Retard ignition timing can reduce $NO_x$ emissions while maintaining high efficiency.

• Journal of Engineering Education Research
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• v.13 no.3
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• pp.87-95
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• 2010

The purpose of this study is to develop and make applications of the teaching materials that are based on the ARCS motivation model for experiments in chemistry. In order to achieve this goal, we researched on the needs of professors, learners, and teacher-assistants and analyzed the contents of the subject. Then we designed and developed teaching materials utilizing the ARCS theory, and made the applications and analyzed their effects. As a result, we found out that the applications of the newly developed teaching materials positively affected the understanding, interest, and concentration of the experiments, and helped the students comprehend various theories better through experiments. The new teaching materials shortened the duration of experiments and reduced the margin of error. They were also helpful preventing accidents and gave students clear ideas about experiments.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.8
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• pp.641-651
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• 2020

This paper implements an antenna selection logic that automatically selects omni-directional antennas mounted on the top and bottom of an unmanned helicopter to maintain the link margin of the data link at 0dB or higher during flight. The selection criteria were derived by simulating and analyzing the radiation pattern. In addition, it is implemented to select the optimal antenna in real time during the flight by deriving the directivity angle function.

• The KSFM Journal of Fluid Machinery
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• v.2 no.1 s.2
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• pp.7-14
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• 1999

This simulation method is developed by using GateCycle code for the performance evaluation of the gas turbine in IGCC(Integrated Gasification Combined Cycle) power plant that uses clean coal gas fuel derived from coal gasification and gas clean-up processes and it is integrated with ASU(Air Separation Unit). In the present simulation method, thermodynamic calculation procedure is incorporated with compressor performance map and expander choking models for considering the off-design effects due to coal gas firing and ASU integration. With the clean coal gases produced through commercially available chemical processes, their compatibility as IGCC gas turbine fuel is investigated in the aspects the overall performance of the gas turbine system. The predictions by the present method show that the reduction of the air extraction from gas turbine to ASU results in a remarkable increase in the efficiency and net power of gas turbines, but it is accompanied with a shift of compressor operation point toward to surge limit. In addition, the present analysis results reveal the influence of compressor performance characteristics of gas turbine have to be carefully examined in designing the ASU integration process and evaluating the overall performance parameters of the gas turbine in IGCC Power plant.

• 한국균학회소식:학술대회논문집
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• 2015.11a
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• pp.14-14
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• 2015

Cellular aspects of sooty mold on walnut leaves were investigated by using light and electron microscopy. A black coating developed on the adaxial leaf surface of a walnut tree. No infestations were found on the abaxial leaf surface with peltate glandular trichomes. Light microscopy showed that fungal complexes from the leaf surface were composed of brown conidia and hyphae. Conidia, with longitudinal and transverse septa, were variable in length ranging from 10 to $30{\mu}m$, and commonly found in clusters, forming microsclerotia. Neither epidermal penetration nor hyphal entrance to host tissues was observed. Based on their morphological characteristics, the fungal complexes were assumed to be Capnodium species. An electron-dense melanized layer was present on the cell wall of multi-celled conidia. Concentric bodies in the fungal cytoplasm had an electron-translucent core surrounded by an electron-dense margin with a fibrillar sheath. Chloroplasts without starch granules in the palisade mesophyll cells of sooty leaves had electron-dense stromata and swollen plastoglobuli. These results suggest that the epiphytic growth of fungal complexes can be attributed to the melanized layer and concentric bodies against a water-deficient environment on the leaf surface. Ultrastructural characteristics of the sooty leaves indicate typical features of dark-adapted and non-photosynthetic shade leaves.

• Nuclear Engineering and Technology
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• v.47 no.3
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• pp.227-239
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• 2015

The thermal, mechanical, and neutronic performance of the metal alloy fast reactor fuel design complements the safety advantages of the liquid metal cooling and the pool-type primary system. Together, these features provide large safety margins in both normal operating modes and for a wide range of postulated accidents. In particular, they maximize the measures of safety associated with inherent reactor response to unprotected, doublefault accidents, and to minimize risk to the public and plant investment. High thermal conductivity and high gap conductance play the most significant role in safety advantages of the metallic fuel, resulting in a flatter radial temperature profile within the pin and much lower normal operation and transient temperatures in comparison to oxide fuel. Despite the big difference in melting point, both oxide and metal fuels have a relatively similar margin to melting during postulated accidents. When the metal fuel cladding fails, it typically occurs below the coolant boiling point and the damaged fuel pins remain coolable. Metal fuel is compatible with sodium coolant, eliminating the potential of energetic fuel-coolant reactions and flow blockages. All these, and the low retained heat leading to a longer grace period for operator action, are significant contributing factors to the inherently benign response of metallic fuel to postulated accidents. This paper summarizes the past analytical and experimental results obtained in past sodium-cooled fast reactor safety programs in the United States, and presents an overview of fuel safety performance as observed in laboratory and in-pile tests.

• Nuclear Engineering and Technology
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• v.48 no.5
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• pp.1071-1082
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• 2016

Korea Atomic Energy Research Institute has been developing a pool-type sodium-cooled fast reactor of the Prototype Gen-IV Sodium-cooled Fast Reactor (PGSFR). To assess the effectiveness of the inherent safety features of the PGSFR, the system transients during design basis accidents and design extended conditions are analyzed with MARS-LMR and the subchannel blockage events are analyzed with MATRA-LMR-FB. In addition, the invessel source term is calculated based on the super-safe, small, and simple reactor methodology. The results show that the PGSFR meets safety acceptance criteria with a sufficient margin during the events and keeps accidents from deteriorating into more severe accidents.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.5
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• pp.397-404
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• 2012

Fragility curves show the probability of a system reaching a limit state as a function of some measure of seismic intensity. To obtain fragility curves of six and twelve story staggered wall structures with middle corridor, incremental dynamic analyses were carried out using twenty two pairs of earthquake records, and their failure probabilities for various intensity of seismic load were investigated. The performances of staggered wall structures with added columns along the central corridor and the structures with their first story walls replaced by columns were compared with those of the regular staggered wall structures. Based on the analysis results it was concluded that staggered wall structures with central columns have the largest safety margin for the same level of seismic load.