• Journal of Navigation and Port Research
• /
• v.33 no.3
• /
• pp.241-245
• /
• 2009

Because of the heat island phenomenon and sea wind, there can be thermal conditions' differences around buildings at downtown and coastal area respectively in coastal city, like Busan, Incheon, Mokpo. For the final purpose of the buildings' energy saving design and operation considering of above mentioned environments differences, energy consumption including heating and cooling loads, electric loads are necessary to be accumulated and analyzed in as the database. As a part of this concept, this study aims to survey and analyze each loads of 22 apartments which has at least 100 households respectively and is located at Yeongdo island, Busan, Korea It is cleared that despite the residents living in this district can use sea wind as a natural ventilation and/or cooling methods, they mainly depends on the electric-driven air-conditioners for cooling with window-closed because of anti-salt problems of the sea wind. This leads the maximum power consumption of the surveyed-22-apartments to be appeared in August like that of inland buildings.

• Journal of Practical Engineering Education
• /
• v.8 no.1
• /
• pp.9-14
• /
• 2016

Depending on the college graduation project and graduation thesis regulations for the certification and graduation requirements, the quadcopter acting as a Li-Po battery that charges by solar energy are proposed a design method and improvements in theory. Quadcopter posture is balanced and confirmed by the position sensor, through a PID (Proportional Integral Differential) control. Battery switching circuit is composed of two Li-Po battery. Driving the quadcopter as one battery, and does not use other battery is charged by solar energy. A battery switching circuit is fabricated in a manner that uses two types of relays. Even if completely not charged to the battery is being driven a certain switch by the battery charging voltage from time to time, it proposes a method for increasing the endurance time and range.

• Journal of Biosystems Engineering
• /
• v.25 no.5
• /
• pp.369-378
• /
• 2000

The purpose of this study is to developed high-efficient rotary tillage system for a power tiller by improving the rotary blade. A kind of the rotary blade with single-edged blade(DS) was developed that requires lower tillage energy than conventional double-edged blade(CD) on the design theory for Japanese rotary blade. In order to find out the tillage characteristics between the single-edged blade and the double-edged blade for power tiller, experiments were performed in soil-bins which were filled up clay loam, loam and sandy loam, and then analyzed the effects of the factors such as soil texture, travelling speed, rotational speed, and tillage depth to each of the blades. And field tests were carried out to compare tillage performances of the two blades using rotary cultivator driven by conventional power tiller. The results of this study were summarized as follows; 1) On the soil bin experiment, it was found that tillage torque of the single-edged blade was less than the ones of the double-edged blade. The decreasing ratios of maximum tillage torque of the single-edged blade to the ones of the double-edged blade were 1 to 8% at clay loam, 5 to 20% at loam and 9 to 31% at sandy loam, respectively. 2) By the field tests, that the tillage performances with the single-edged blade compared with the double-edged blade was improved about 19% in field capacity, about 34% in fuel consumption, and 12.5% in soil breaking ratio. Furthermore, the fluctuation of engine speed, the variation of exhaust gas temperature, and the amount of soil clogging on the blade and straw wound on the rotary shaft showed lower values with the developed blade than the conventional blade. So, it may be concluded that tillage performance by the developed single-edged blade was improved compared with the one by the conventional double-edged blade.

• The KIPS Transactions:PartD
• /
• v.18D no.4
• /
• pp.309-312
• /
• 2011

Handling fuzzy query in voice search on smartphones is one of the most difficult problems. It is mainly derived from the complexity and the degree of freedom of natural language. To reduce the complexity and the degree of freedom of fuzzy query in voice search on smartphones, attribute-driven approach for fuzzy query is proposed. In addition, a new page ranking algorithm based on the values of attributes for handling fuzzy query is proposed. It provides a smartphone user with location-based personalized page ranking based on user's search intentions. It is a further step toward location-based personalized web search for smartphone users. In this paper, we design a prototype model for handling fuzzy query in voice search on smartphones and show the experimental results of the proposed approach compared to existing smartphones.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.20 no.4
• /
• pp.558-565
• /
• 2017

The vehicle-mounted mine detection system with large detection sensor modules can search wide areas with a fast detection speed. To mount the heavy mine detectors on a manned or unmanned vehicle, it is necessary to design the detector driving mechanism and control system based on the considerations driven from the characteristic analysis and the operation requirements of the detection system. Furthermore, while operating the mine detector mounted on a mobile vehicle, it is significant to keep the height from the ground to sensors within a certain distance in order to get a qualified detection performance. As the mine detection sensor, we used ground penetrating radar widely used to geotechnical exploration, mine detection and etc. In this paper, we introduce a driving mechanism through analyzing the characteristics of the vehicle-mounted mine detection system. We also suggest a method to automatically control the distance between the ground and GPR by utilizing the GPR output values, used to detect mines at the same time.

• Journal of Computing Science and Engineering
• /
• v.1 no.2
• /
• pp.177-194
• /
• 2007

Index selection is one of the most important decisions to take in the physical design of relational data warehouses. Indices reduce significantly the cost of processing complex OLAP queries, but require storage cost and induce maintenance overhead. Two main types of indices are available: mono-attribute indices (e.g., B-tree, bitmap, hash, etc.) and multi-attribute indices (join indices, bitmap join indices). To optimize star join queries characterized by joins between a large fact table and multiple dimension tables and selections on dimension tables, bitmap join indices are well adapted. They require less storage cost due to their binary representation. However, selecting these indices is a difficult task due to the exponential number of candidate attributes to be indexed. Most of approaches for index selection follow two main steps: (1) pruning the search space (i.e., reducing the number of candidate attributes) and (2) selecting indices using the pruned search space. In this paper, we first propose a data mining driven approach to prune the search space of bitmap join index selection problem. As opposed to an existing our technique that only uses frequency of attributes in queries as a pruning metric, our technique uses not only frequencies, but also other parameters such as the size of dimension tables involved in the indexing process, size of each dimension tuple, and page size on disk. We then define a greedy algorithm to select bitmap join indices that minimize processing cost and verify storage constraint. Finally, in order to evaluate the efficiency of our approach, we compare it with some existing techniques.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.7
• /
• pp.1568-1574
• /
• 2009

One of the most difficult problems in user requirement engineering is the communication gap that exists between different end-users, stakeholders, and software engineers. Since scenarios allow different stakeholders to describe and review the problem in their own language instead of some abstract model, they are also a solution to the problem. We propose a progressive, iterative and interleaved process of using scenario at different requirement engineering stages including elicitation, analysis and validation. This process model has been applied to our TRES System. In our proposed system, we combine prototype, scenarios and use cases in a single and comprehensive framework to avoid most of the shortcomings in other tools. Our system is an XML-based system for scenario-driven requirement engineering. Within the TRES system, scenarios are stories capture information about users and their tasks, including the context of use. In our TRES system, scenarios are stored in XML-based database and described using XML notation.

• The KIPS Transactions:PartB
• /
• v.15B no.3
• /
• pp.189-196
• /
• 2008

In this paper, a CMOS digital image sensor, which consists of A/D conversion, motion estimation circuits, and an attention module for ROI (Region of Interest) detection is presented. The functions of A/D conversion and motion estimation are implemented by $0.6{\mu}m$ CMOS processing circuit as hardware, and the attention module is implemented outside the circuit as software currently. Attention modules are taken to improve limited applications of the smart image sensor. The current smart image sensor responses to the changes of intensity, and uses the integration time to estimate motion. Therefore it is limited in its applications. To make up for inherent property of the sensor from circuit design and extend its applications we decide to introduce perception solutions to the image sensor. Attention modules for still and moving images are employed to achieve such purposes. The suggested approach makes the smart image sensor available with additional functions for such cases that motion estimation or intensity changes are not observed. Experimental result shows the usefulness and extension of the image sensor.

• Journal of the Korean Institute of Gas
• /
• v.12 no.2
• /
• pp.12-17
• /
• 2008

The In recent years, the need for more fuel-efficient and lower-emission vehicles has driven the technical development of alternative fuels such as LPG (Liquefied Petroleum Gas) which is able to meet the limits of better emission levels without many modifications to current engine design. LPG has a high vapor pressure and lower viscosity and surface tension than diesel and gasoline fuels. These different fuel characteristics make it difficult to directly apply the conventional gasoline or diesel fuel pump. In this study, experiments are performed to get initial performance and efficiency of the fuel pump under different condition of the temperature and composition of fuel. The characteristics of vane type fuel pump were investigated to access the applicability on LPLi engine.

• Journal of Advanced Marine Engineering and Technology
• /
• v.29 no.3
• /
• pp.297-305
• /
• 2005

The evaporation heat transfer coefficient of $CO_2$ (R-744) in a horizontal tube was investigated experimentally. The experiments were conducted without oil in a closed refrigerant loop which was driven by a magnetic gear pump. The main components of the refrigerant loop are a receiver. a variable-speed pump. a mass flow meter. a pre-heater and evaporator (test section). The test section consists of a smooth. horizontal stainless steel tube of 7.75 mm inner diameter. The experiments were conducted at mass flux of 200 to $500\;kg/m^{2}s$. saturation temperature of $-5^{\circ}C\;to\;5^{\circ}C$. and heat flux of 10 to $40\;kW/m^2$. The test results showed the evaporation heat transfer of $CO_2$ has greatly effect on more nucleate boiling than convective boiling. The evaporation heat transfer coefficients of $CO_2$ are highly dependent on the vapor quality. heat flux and saturation temperature. The evaporation heat transfer coefficient of $CO_2$ is very larger than that of R-22 and R-134a. In making a comparison between test results and existing correlations. the present experimental data are the best fit for the correlation of Jung et al. But it was failed to predict the evaporation heat transfer coefficient of $CO_2$ using by the existing correlation. Therefore. it is necessary to develop reliable and accurate predictions determining the evaporation heat transfer coefficient of $CO_2$ in a horizontal tube.