• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.2
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• pp.315-322
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• 2002

A thin film oxide semiconductor micro gas sensor array which shows only 60㎽ of power consumption at an operating temperature of 30$0^{\circ}C$ has been fabricated using microfabrication and rnicrornachining techniques. Excellent thermal insulation of the membrane is achieved by the use of a double la! or structure of 0.1${\mu}{\textrm}{m}$ thick Si$_3$N$_4$ and 1${\mu}{\textrm}{m}$ thick phosphosilicate glass(PSG) prepared by low pressure chemical vapor deposition(LPCVD) and atmospheric－pressure chemical-vapor deposition(APCVD), respectively. The sensor way consists of such thin film oxide semiconductor sensing materials as 1wt.％ Pd-doped SnO$_2$, 6wt.% AI$_2$O$_3$-doped ZnO, WO$_3$ and ZnO. The thin film oxide semiconductor micro gas sensor array exhibited resistance changes usable for subsequent data processing upon exposure to various gases and the sensitivity strongly depended on the sensing layer materials. Heater Part of the sensor structure has been modified in order to improve the process yield of the sensor, and as a result of modified heater structure improved process yield has been achieved.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.2 no.3
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• pp.103-122
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• 2007

Innovation clusters developed or evolved around a specific region IS the key element of national innovation system and determine national competitiveness. Recognizing the importance of innovation clusters, Korean government has made "Daedeok Special R&D Zone" in 2005. This paper examines the success factors of famous Cluster in advanced countries and China, and proposes the strategy for regional development in Daejeon through boosting Daedeok Innovation Cluster. Although 30.5% of government R&D investment is being concentrated in Daedeok along with 10% of the country's doctorate degree holders, it is lack of increasing revenue by linking corporate R&D with a creative and challenging entrepreneur spirit. The core of the innovation cluster is the integration and mutual networking of the main participants. This paper suggests strategies for developing as a world class innovation cluster, global networking and clustering, venture ecosystem formation, commercialization the knowledge by interacting with market. It also explains the necessity of regional integration for cluster to cluster linkages in the East Asia Region.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.1
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• pp.47-51
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• 2017

Recently international cooperations are formed to deal with the environmental pollution of the atmosphere generated by the vapor compression refrigeration system. A refrigeration technique, which can replace existing CFC refrigerants that are the main cause of environmental contamination, has received greater attention. Magnetic refrigeration is a refrigeration technique using the magnetocaloric effect of the magnetic material, and is an eco-friendly refrigeration technology using the solid refrigerant instead of CFC refrigerants. Also it is regarded as an efficient refrigeration system to generate temperature difference between high and low sides using the temperature change of magnetic refrigerants according to the change of magnetic field, instead of using power-consuming and noisy compressor. In this paper, we introduce the magnetic refrigeration apparatus using concentric Halbach cylinder permanent magnets and the experimental results using the apparatus.

• 전자공학회논문지 IE
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• v.46 no.4
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• pp.16-24
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• 2009

In this paper, we propose a new noise cancellation system for the NDIR based optical analyzer, that can measure various environmental air-pollution materials (CO, $SO_2$, NOx, etc.) in real-time. The sensed signals are contaminated by the different noise sources that measurement noise with high frequencies and the drift noise with the low frequencies. They can be eliminated by a pre-processing that considering their time-domian properties and by a post-processing that using sub-power ratios in subband structure. In the proposed method, the ore and pose-processing for noise cancelling are useful for hardware implementation of the NDIR based optical analyzer with a precision measuring.

• Journal of the Korea Society of Computer and Information
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• v.20 no.4
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• pp.77-85
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• 2015

Recently, wireless sensor network(WSN) have been used in various fields to implement ubiquitous computing environment. WSN uses small, low cost and low power sensors in order to collect information from the sensor field. This paper proposes a clustering algorithm for energy efficiency of sensor nodes. The proposed algorithm is based on conventional LEACH, the representative clustering protocol for WSN and it prolongs network and nodes life time using sleep technique and changable transmission mode. The nodes of the proposed algorithm first calculate their clustering participation value based on the distance to the neighbor nodes. The nodes located in high density area will have clustering participation value and it can turn to sleep mode. Besides, proposed algorithm can change transmission method from conventional single-hop transmission to multi-hop transmission according to the energy level of cluster head. Simulation results show that the proposed clustering algorithm outperforms conventional LEACH, especially non-uniformly deployed network.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.10
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• pp.40-45
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• 2009

In this paper, we introduce a mobile-type tiny sensor device that can classify the activities of daily living based on the state-dependent motion analysis using a 3-axial accelerometer in real-time. The device consists of an accelerometer, GPS module, 32bit micro-controller for sensor data processing and activity classification, and a bluetooth module for wireless data communication. The size of device is 50*47*14(mm) and lasts about 10 hours in operation-mode and 160 hours in stand-by mode. Up to now, the device can recognize three user activities ("Upright", "Running", "Walking") based on the decision tree. This tree is constructed by the pre-learning process to activities of subjects. The accuracy rate of recognizing activities is over 90% for various subjects.

• Journal of Advanced Navigation Technology
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• v.22 no.5
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• pp.485-489
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• 2018

For the construction of smart factory that are part of the Fourth Industrial Revolution, data from the production environments and production machines should be collected, analyzed, and feedback should be given to predict when failures take place or parts should be replaced. For this purpose, a system that monitors the production environments and the status of the production machines are required. In this paper, the monitoring system for mobile devices and PC is implemented by collecting environmental data from production sites and sensor data of production machine using LoRa, a low-power wireless communication technology. On the mobile devices, production environments and vibration data can be displayed in real time. In PC monitoring program, sensor data can be displayed graphically to check standard deviation and data variation. The implemented system is used to collect data such as temperature, humidity, and atmospheric pressure of the production environment, and vibration data of production machines.

• Journal of Advanced Marine Engineering and Technology
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• v.41 no.3
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• pp.245-250
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• 2017

Worldwide environmental regulations have been enhanced for emission reduction of greenhouse gases and air pollutants; accordingly, some measures were prepared. Furthermore, the need for effective and reasonable energy-saving methods is growing in accordance with that for environmental pollution minimization. In the case of marine engineering, techniques for the development of eco-friendly vessels have been actively studied, including reduction of exhaust gas emissions, development of alternative fuel, and development of a new propulsion system. In this study, we presented the basic concepts and analyzed the speed, current, voltage, and output power characteristics of each operating mode, i.e., operating mode of battery, generator, and full power.

• Journal of the Korean Regional Science Association
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• v.33 no.1
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• pp.3-16
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• 2017

This paper analyzed 16 regional total factor energy efficiency (TFEE) of the Korean manufacturing sector using data envelopment analysis method for the period of 2005-2013. According to the empirical results, it is necessary to use TFEE as well as partial energy efficiency defined by the ratio of energy usage to output (energy intensity) when we compare energy efficiency. Secondly, TFEE in the Korean manufacturing sector is quite different across 16 regions. For example, Gangwon province should improve energy efficiency by 55% compared to Seoul, Gwangju, Ulsan, and Gyeongbuk which are located on production frontier. Furthermore, the estimation of panel tobit regression model showed that the higher non fossil fuel using, the higher production share of large-sized firms, the lower energy intensity, and the lower capital-labor ratio could have positive effect on TFEE.

• Journal of the Korea Organic Resources Recycling Association
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• v.22 no.3
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• pp.60-67
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• 2014

Exhaust system used in toilet and cooking place of high riser public house is roof fan of two basic types : natural roof ventilator and natural/forced roof ventilator. Natural/forced roof ventilator has a motor in the rotary shaft. There are many high riser public house in Korea. These buildings were not viewed as being major contributors to exhaust pollutants producted in indoor. It was because many engineers thought that exhaust in high riser building depend on stack effect. This study investigates on stack pressure determined by exterior pressure and the difference pressure control in exhaust stack used in high riser public house. This paper focuses mainly on the effect of the time interval for power supply of motor installed in roof fan with function of natural wind velocity and of exhaust air volume of toilet. It is observed there are higher exhaust efficiency than the existing natural roof ventilator.