• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.5
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• pp.1178-1184
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• 2010

In this paper, a mobile search engine architecture that predicts user's search words and recommends them to users in estimated preference order without having additional user inputs. Information obtained from sensors is first sent to the recommendation engine. The related contents are extracted from the context and history databases and recommending words are selected from the contents. Finally, the words are delivered to the mobile device for suggestion. To evaluate the implemented system response time is measured. A satisfaction survey is also performed for 50 users, and improvement in the proposed system is observed.

• Journal of KIISE:Databases
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• v.29 no.2
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• pp.148-157
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• 2002

Caching in meta-search engines can improve the response time of users' request. We describe the cache scheme in our meta-search engine in terms of its architecture and operational flow. In particular, we propose a popularity-driven cache algorithm that utilizes popularities of queries to determine cached data to be purged. The popularity is a value that represents the normalized occurrence frequency of user queries. This paper presents how to collect popular queries and how to calculate query popularities. An empirical performance evaluation of the popularity-driven caching with the traditional schemes (i.e., least recently used (LRU) and least frequently used (LFU)) has been carried out on a collection of real data. In almost all cases, the proposed replacement policy outperforms LRU and LFU.

• Journal of the Korea Convergence Society
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• v.8 no.3
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• pp.15-22
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• 2017

People generally believe that disaster forecast and warning systems and response systems are well established in the age of cutting edge technology. As a matter of fact, reliable systems to respond to disasters are not properly equipped, as we witnessed the Sewol ferry disaster in 2014. The existing forecast and warning systems are based on sensor information with low efficiency, and image information is only operated by monitoring staff manually. In addition, the interconnection between a warning system and a response system in order to decide how to cope with the recognized disaster is very insufficient. This paper introduces the CCTV based disaster recognition and real time crisis response system composed of the CCTV image recognition engine and the crisis response technique. This system has brought the possibility to overcome the limitations of existing sensor based forecast and warning systems, and to resolve the problems in the absence of monitoring staff when responding to crisis.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.6
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• pp.593-600
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• 2012

The exergy characteristics for R245fa and water working fluids have been analyzed for an electric generation system utilizing the Rankine cycle to recover heat from the wasted exhaust gas from a diesel engine used for the propulsion of a large ship. The theoretical calculation results showed that the efficiencies of exergy and system exergy improved as the turbine inlet pressure increased for R245fa at a fixed mass flow rate. Furthermore, the exergy destruction rates of the condenser and evaporator were relatively larger than those in other components. The exergy efficiency of the system increased with increasing mass flow rate. For a water working fluid, although the exergy destruction rate of the evaporator was similar to that for R245fa, the exergy loss rate varied significantly in response to variations in the pressure and mass flow rates at the turbine inlet.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.6
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• pp.788-794
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• 2019

Recently, global climate change caused by greenhouse gases has emerged as a significant air-environmental problem. Technical innovation in response to this phenomenon is ongoing, with an emphasis on the environmental impacts of unusually high temperatures and unexpected heavy rainfall. In this study, we investigated the effects of temperature change on air pollution for a concomitant rapid temperature increase. The test conditions include loading from 0 % to 100 % at 1400 rpm, 1600 rpm, and 1800 rpm for a change in the intake air temperature of a marine diesel engine from 20 ℃ to 50 ℃. The experimental results revealed that CO and HC decreased slightly, whereas the brake specific fuel consumption, NOx, and PM increased slightly when the intake air temperature changed. In addition, it was determined that the combustion temperature did not change significantly.

• Journal of the Korean Institute of Telematics and Electronics
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• v.17 no.5
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• pp.15-21
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• 1980

An engine control system in which the conventional mechanical ignition system is studied. The contact point of the breaker is replaced by the contactless magnetic pick up sensor from which the information of the speed and the position of the crankshaft is extracted , and further an electronic High Energy Ignitim System Is designed, implemented and tested . The High Energy Igniticwl System increases the secondary spark voltage of the ignition coil from the conventional 10000~15000 volts to the 30000~40000 volts resulting in improving the combustion efficiency. Also, instead of the conventional advimce mechanism forigniliontiming control, a microprocessorbased timinng mechanisn is installed to determine the ignition timing data in response to the engine rpm and the intake manifold vacuum.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.5
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• pp.325-332
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• 2022

The vertical take-off and vertical landing (VTVL) function is essential to carry out exploration missions on the moon or Mars. For this, the engine of the exploration vehicle must have appropriate thrust control accuracy and response time. The hybrid rocket engine (HRE) is known to have a high level of thrust control capability that can satisfy these conditions. This study aims to first verify whether the thrust control performance of the developed HRE is suitable for VTVL. To this end, an oxidizer supply system that does not use a pressurization device was adopted, aiming for a mission time of about 10 seconds. In this study, the thrust control characteristics appearing under various supply pressure decreasing conditions were identified through experiments. Appropriate tank and charging conditions were set from the experimental results. In addition, the results of previous studies and current study's test were compared to confirm whether the developed HRE had adequate control performance for VTVL, and finally, the thrust control performance was verified through altitude control simulation.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.31 no.2
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• pp.81-88
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• 2023

SHM (Structural Health Monitoring) technique for monitoring aircraft structural health and damage, EHM (Engine Health Monitoring) for monitoring aircraft engine performance, and APM (Application Performance Management) is used for each function. APMS (Airplane Performance Monitoring System) is a program that comprehensively applies these techniques to identify the difference between the performance manual provided by the manufacturer and the actual fuel mileage of the aircraft and reflect it in the flight plan. The main purpose of using APMS is to understand the performance of each aircraft, to plan and execute flights in an optimal way, and consequently to reduce fuel consumption. First, it is to check the fuel efficiency trend of each aircraft, check the correlation between the maintenance work performed and the fuel mileage, find the cause of the fuel mileage increase/decrease, and take appropriate measures in response. Second, it is to find the cause of fuel mileage degradation in detail by checking the trends by engine performance and fuselage drag effect. Third, the APMS is to be used in making maintenance work decisions. Through APMS, aircraft with below average fuel mileage are identified, the cause of fuel mileage degradation is identified, and appropriate corrective actions are determined. Fourth, APMS data is used to analyze the economic analysis of equipment installation investment. The cost can be easily calculated as the equipment installation cost, but the benefit is fuel efficiency improvement, and the only way to check this is the manufacturer's theory. Therefore, verifying the effect after installation and verifying the economic analysis is to secure the appropriateness of the investment. Through this, proper investment in fuel efficiency improvement equipment will be made, and fuel efficiency will be improved.

• Science of Emotion and Sensibility
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• v.15 no.4
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• pp.503-516
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• 2012

According to the researches of robot and software agent until now, computational emotion model is dependent on system, so it is hard task that emotion models is separated from existing systems and then recycled into new systems. Therefore, I introduce the Engine of computational Emotion model (shall hereafter appear as EE) to integrate with any robots or agents. This is the engine, ie a software for independent form from inputs and outputs, so the EE is Emotion Generation to control only generation and processing of emotions without both phases of Inputs(Perception) and Outputs(Expression). The EE can be interfaced with any inputs and outputs, and produce emotions from not only emotion itself but also personality and emotions of person. In addition, the EE can be existed in any robot or agent by a kind of software library, or be used as a separate system to communicate. In EE, emotions is the Primary Emotions, ie Joy, Surprise, Disgust, Fear, Sadness, and Anger. It is vector that consist of string and coefficient about emotion, and EE receives this vectors from input interface and then sends its to output interface. In EE, each emotions are connected to lists of emotional experiences, and the lists consisted of string and coefficient of each emotional experiences are used to generate and process emotional states. The emotional experiences are consisted of emotion vocabulary understanding various emotional experiences of human. This study EE is available to use to make interaction products to response the appropriate reaction of human emotions. The significance of the study is on development of a system to induce that person feel that product has your sympathy. Therefore, the EE can help give an efficient service of emotional sympathy to products of HRI, HCI area.

• Journal of Fisheries and Marine Sciences Education
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• v.12 no.2
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• pp.142-151
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• 2000

The studies on the electronic control fuel injection system for a DI diesel engine have done for reducing the exhaust emission and improving fuel consumption. The electronic control fuel injection system is classified into a common rail system, a unit injector system and a high pressure injection system. The characteristics of these systems are largely depends on the operating characteristics of its solenoid that have high speed on-off operation. In order to improve these characteristics of fuel injection system, it is necessary to design the optimal shape of solenoid and select the input method of its power source. It was proposed HELENOID, COLENOID, DISOLE, and Multipole Solenoid in the studies of design for the optimal shape of solenoid. The studies on the energizing method, input method for power of solenoid were dealt with the conventional energizing method, the chopping method and the pre-energizing method. In order to find out the high response characteristics of solenoid, it is necessary to test the performance of optimally designed solenoid with a new energizing method. In this paper, the solenoid of multi-pole type with plat armature and its power control unit to control input current by the chopping method designed, and its response tests were performed according to its energizing conditions. As a result, the maximum input current for solenoid was controlled by the period of first stage exciting current and chopping duty ratio of control stage exciting current, and the fastest "on" time was able to get 0.46ms. The conditions of fastest "on" time was 0.3ms for first stage exciting current, 0.16ms for control exciting current and 75% for chopping duty ratio.