• Animal cells and systems
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• v.2 no.1
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• pp.65-69
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• 1998

The hippocampus and prefrontal cortex are regarded as the highest-order association cortices. The hippocampus has been proposed to store "cognitive maps" of external environments, and the prefrontal cortex is known to be involved in the planning of behavior, among other functions. Considering the prominent functional roles played by these structures, it is not surprising to find direct monosynaptic projections from the hippocampus to the prefrontal cortex. Rhythmic stimulation of this projection patterned after the hippocampal EEG theta rhythm induced stable long-term potentiation of field potentials in the prefrontal cortex. Comparison of behavioral correlates of hippocampal and prefrontal cortical neurons during an a-arm radial maze, working memory task shows a striking contrast. Hippocampal neurons exhibit clear place-specific firing patterns, whereas prefrontal cortical neurons do not show spatial selectivity, but are correlated to different stages of the behavioral task. These data lead to the hypothesis that the role of hippocampal projection to the prefrontal cortex is not to impose spatial representations upon prefrontal activity, but to provide a mechanism for learning the spatial context in which particular behaviors are appropriate.propriate.

• Journal of the korean Society of Automotive Engineers
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• v.7 no.1
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• pp.48-54
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• 1985

One of the most probable reason of the apex seal damage in IR-2500 industrial Wankel (rotary) engine was believed to be the engine detonation. Both analytical and experimental studies were made with a view th find out engine detonation pressure. The stagnation detonation pressure $p_{03}$' was estimated based on the data from IR-2500 engine detonation tests, such as engine firing pressure, state of fresh charge at BDC and polytropic compression exponent. The estimated stagnation detonation pressure for the natural gas fueled IR-2500 engine was in excess of 3,700 psia. With natural gas liquid added to the natural gas the octane value of the fuel was lowered, thus, making the engine more prone to detonate. The estimated detonation pressure for the case with the mixed fuel was about 3,400 psia which was sufficiently high to break the apex seal. The subsequent engine lab tests performed on two identical engines with sole difference in the apex seal thickness between the two engines proved that the engine knock, in fact, was the villain of the apex seal failure.ilure.

• Journal of the military operations research society of Korea
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• v.29 no.2
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• pp.61-80
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• 2003

A fire sequencing problem is considered. Fire sequencing problem is a kind of scheduling problem that seeks to minimize the overall time span under a result of weapon­target allocation problem. The assigned weapons should impact a target simultaneously and a weapon cannot transfer the firing against another target before all planned rounds are consumed. The computational complexity of the fire sequencing problem is strongly NP­complete even if the number of weapons is two, so it is difficult to get the optimal solution in a reasonable time by the mathematical programming approach. Therefore, a genetic algorithm is adopted as a solution method, in which the representation of the solution, crossover and mutation strategies are applied on a specific condition. Computational results using randomly generated data are presented. We compared the solutions given by CPLEX and the genetic algorithm. Above $7(weapon){\times}15(target)$ size problems, CPLEX could not solve the problem even if we take enough time to solve the problem since the required memory size increases dramatically as the number of nodes expands. On the other hand, genetic algorithm approach solves all experimental problems very quickly and gives good solution quality.

• Journal of the Korean Society of Propulsion Engineers
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• v.8 no.3
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• pp.61-67
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• 2004

The extinction characteristics of the solid propellant were studied experimentally in this paper. These characteristics are required for designing TCO (thrust cut off) system of the solid rocket motor Parameters to characterize solid propellant extinction were defined by physical observation. A device was designed (or acquiring these parameters and the firing tests were implemented to get the preliminary data for the extinction characteristics of HTBP propellant.

• Journal of the korean Society of Automotive Engineers
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• v.5 no.2
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• pp.15-20
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• 1983

The nature and the sources of sound in cars is discussed in the light of many previous works, and the importance of the system resonances inside cars is suggested. An investigation of a 'boom' problem in a small size passenger car is described. It was established that the 'boom' frequencies coincided with engine firing frequency and also with several system resonances. To find out main transmission path of the noise to the car interior, various possible sources were eliminated from the investigation by means of simple modification to the vehicle. Data on the structural modes of the body, and the acoustic modes of the passenger compartment at various forcing cases were obtained to provide better understanding of the problem. It was found that the acoustic resonance responsible for the boom was controlled largely the bending motion of the floor. To investigate the effect of the structural modification to the acoustic response, center floor of the car was reinforced. a great reduction of the noise inside the car especially at the offending speed range, was achieved by this modification.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.351-355
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• 2003

In this paper, a new barrier rib forming method of embossed barrier rib (EBR) formation process for the PDP rear panel was introduced. The process is mainly composed of green sheet fabrication, lamination of the green sheet on the rear glass panel having data electrodes, and roll embossing followed by firing. The EBR process has two advantages over the conventional barrier rib forming methods. One is the process requires less equipment investment than the conventional methods by about 20% of the current rear panel fabrication equipment investment owing to the simplified fabrication process. The other advantage is its reduced rear panel manufacturing cost by eliminating the time consuming and complicated processes and waste of materials in the conventional methods. In this study, general procedure of EBR fabrication process is described and the characteristics of prototype PDP using EBR panel are discussed.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.6
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• pp.132-145
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• 2008

We propose a new technique for autonomous navigation and travelling of mobile robot based on ultrasonic sensors through the narrow labyrinth that leave only distance of a few centimeters on each side between the guides and the robot. In our current implementation the ultrasonic sensor system fires at a rate of 100 ms, that is, each of the 8 sensors fires once during each 100 ms interval. This is a very good firing rate, implemented here for optimal performance. This paper presents an extensively tested and verified solution to the problem of obstacle avoidance. Our solution is based on the optimal placement of ultrasonic sensors at strategic locations around the robot. Both the sensor location and the associated navigation algorithm are defined in such a way that only the accurate radial sonar data is used for accurate travelling.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.1113-1116
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• 1999

For mobile robot, the navigation effectiveness can be improved by providing autonomy, but this autonomy requires the mobile robot to detect unknown obstacles and avoid collisions while moving it toward the target. This paper presents an effective method for autonomous navigation of the mobile robot in structured environments. This method uses ultrasonic sensor array to detect obstacles and utilizes force relationship between the obstacles and the target for avoiding collisions. Accuracy of sensory data produced by ultrasonic sensors is improved by employing error eliminating rapid ultrasonic firing (EERUF) technique. Navigation algorithm controlling both the velocity and steering simultaneously is developed, implemented to the mobile robot and tested on the floor filled with the cluttered obstacles. It is verified that from the results of the field tests the mobile robot can move at a maximum speed of 0.66 m/sec without any collisions.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.305-310
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• 2003

Recently, gypsum boards are widely used as interior finishing boards for constructions because of their features of absorbing heats and little temperature rising at the early stage of fire. Therefore, in this research, basic data were suggested to secure fireproof stability by investigating interior processing features, which change together with the backside temperature of test materials from Flash Over (within 30 minutes after firing), at which temperature reaches its highest point, to survey the features of materials due to rising temperature in the chase of gypsum boards (general and fireproof gypsum boards)

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.333-337
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• 2003

In this paper, 5.2 GHz WLAN BPF(Band Pass Filter) using LTCC(Low temperature co-firing ceramic) Multilayer technology was simulated and manufactured. A DGS(Defected Ground structure) resonator with spiral ground pattern is used to shorten resonator size and improve circuit Q factor. And the equivalent circuit of BPF was suggested. The measured result shows good agreement with simulated data. Experimental results show the center frequency of 5.25GHz, the insertion loss of 0.14dB, and the 3-dB bandwidth of 350MHz (6%). The center frequency of BPF is 5.25GHz which is available for wireless LAN.