• Journal of the Society of Naval Architects of Korea
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• v.35 no.1
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• pp.54-60
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• 1998

Generally, spiral test has been used for evaluating course-keeping quality of a ship. But, there are many difficult problems in performing spiral test and reversed spiral test. Therefore, we propose zig-zag test instead of spiral test for evaluating curse-keeping quality of a ship. In this paper, K-T maneuvering response model is applied to the spiral curves which are systematically produced to calculate Zig-zag maneuver. Then, 1st overshoot angle and 2nd overshoot angle are plotted. And the relations between overshoot angles and band widths of spiral curve are discussed.

• Proceedings of the Korean Society of Computer Information Conference
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• 2019.01a
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• pp.95-97
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• 2019

본 논문에서는 ZigBee 기반의 WSN과 노드 연결을 위한 새로운 기법을 제안한다. 이 기법은 통신 노드 간에 격리된 노드의 수를 최소화하기 위해 수신신호강도(RSSI) 샘플에 적용된 딕슨 테스트(Dixon's test)를 사용하여 ZigBee 기반의 WSN을 위한 새로운 노드 연결 구조로써 특이점(outlier)을 제거하여 적은 수의 RSSI 값으로도 정확한 노드 연결이 가능하다. 본 논문에서는 시뮬레이션을 통하여 제안하는 기법이 기존의 RSSI 기반의 기법보다 더 높은 정확도를 유지하면서 처리 시간은 줄어든 것을 증명하였다.

• The KSFM Journal of Fluid Machinery
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• v.19 no.3
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• pp.37-42
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• 2016

The demand for wireless technology in plant structure has recently been increasing due to several advantages such as installation cost reduction, easy placement, easy extension and aesthetic benefits. Among the many wireless technologies, ZigBee is one of the most useful for plant structure; a wireless plant networking system can be configured using ZigBee alone. This research proposes a ZigBee to use for extreme cold region and thereby enable integration of wired and wireless plant monitoring systems. In this study, in order to assess the performance of ZigBee measured data by thermocouple were examined based on the results from laboratory tests between existing ZigBee and developed ZigBee. From the experiment results, performance of developed ZigBee in harsh environment can be increased well.

• Journal of Navigation and Port Research
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• v.33 no.9
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• pp.603-608
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• 2009

In this paper, a 3m-class free running model ship will be introduced with its manoeuvring performance experiments. The results of turning circle test and zig-zag test will be explained. The developed system are equipped with GPS, main control computer, wireless LAN, IMU (Inertial Measurement Unit), self-propulsion propeller and driving rudder. Its motion can be controlled by RC (Radio Control) and wireless LAN from land based center. Automatic navigation is also available by pre-programmed algorithm. The trajectory of navigation can be acquired by GPS and it provides us with important data for ship's motion control experiments. The results of manoeuvring performance experiment have shown that the developed free running model ship can be used to verify the test of turning circle and zig-zag. For next step, other experimental researches such as ship collision avoidance system and automatic berthing can be considered in the future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.7
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• pp.3220-3226
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• 2011

In order to monitor internal risk factors such as fire, terror, etc. on the subway station, the surveillance systems using CCTV and various kinds of sensors have been implemented and recently, introduction of surveillance systems using an advanced IT technology, sensor network technology is tried on several areas. Since 2007, Korean government has made an effort to develop the intelligent surveillance and monitoring system, which can monitor fire, intrusion, passenger congestion, health-state of structure, etc., by using wireless sensor network technology and intelligent video analytic technique. For that purpose, this study carried out field wireless communication environment test on Chungmuro Station of Seoul Metro on the basis of ZigBee that is considered as a representative wireless sensor network before field application of the intelligent integrated surveillance system being developed, arranged and analyzed and ZigBee based wireless communication environment test results on the platform and waiting room of Chungmuro Station on this paper. Results of wireless spectrum analysis on the platform and waiting room showed that there is no radio frequency overlapped with that of ZigBee based sensor network and no frequency interference with adjacent frequencies separated 10MHz or more. As results of wireless data transmission test using ZigBee showed that data transmission is influenced by multi-path fading effect from the number and flow rate of passengers on the platform or the waiting room rather than effects from entrance and exit of the train to/from the platform, it should be considered when implementing the intelligent integrated surveillance system on the station.

• 전자공학회논문지 IE
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• v.46 no.3
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• pp.48-54
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• 2009

In this paper, a test method of HDMI connectors is developed using a test zig. This method is used to test the characteristic for a digital signal connector, and is applied the compliance test specification. The test results of connectors for the two manufactory are implemented by the new proposed method. Finally, it is suggested to the new test method of HDMI connector in this paper, and is applied to the simple test method of connector in manufactory.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.10B
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• pp.644-654
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• 2007

ZigBee is one of wireless communication standards and many applications based on Zigbee have been developing for commercial applications. Most of those applications require links to Internet like Zigbee service gateways. However, ZigBee service gateway should provides following functions to be effectively utilized itself: translation of messages between diverse ZigBee application profiles and message formats used in Internet, addition/removal of a new ZigBee service without stopping existing services according to addition/removal of a Zigbee node, and no transmission of unwanted packets to ZigBee network. Therefore, this paper proposes a new type of ZigBee Service Gateway, called ZiGate to provide the functions. The proposed ZiGate is capable of re-configurating message translation modules required in case of addition/removal of nodes and doesn't transmit unnecessary packets to the ZigBee networks by synchronizing itself with ZigBee network. And ZiGate provides translation modules between messages defined in Zigbee application profiles and both text-based and binary-based messages used in Internet. In this paper we implements the ZiGate and evaluates it on the test bed. This evaluations show that the proposed ZiGate works efficiently.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.8
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• pp.121-128
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• 2007

In this thesis, we would show how to lay out and produce the shell-type transformer using the world's first Zig-Zag winding way, instead of a general winding. Also, we omit the progress of varnish-impregnation, so that we could develop the new shell-type transformer winding which improves the short-circuit characteristics and dielectric strength. It has a copernican effect to reduce the thickness and the number of insulation papers, as compared with a general winding transformer. We would prove that it is far superior in cost reduction, loss reduction, and mechanical force of short-circuit. And eventually you must find it useful in the pole transformer for power distribution in the domestic power companies.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.9
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• pp.1939-1946
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• 2012

USNs (Ubiquitous Sensor Networks) such as IEEE 802.15.4 ZigBee network share ISM (Industrial, Scientific, and Medical) frequency band with WiFi networks. Once both networks operate in a region, packet collision may happen because of frequency overlapping. To assure this possibility, we conducted experiments where WiFi and ZigBee communication networks had been installed in an area. As a result of the test, successful data transmission rate were reduced due to the frequency overlapping between a WiFi communication channel and a ZigBee communication band. To cope with this problem, we propose a collision avoidance algorithm. In the proposed algorithm, if frequency collision is sensed, new communication channel with different frequency band is allocated to each node. Performance of the proposed frequency collision avoidance algorithm was tested and the results were described.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.53 no.2
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• pp.177-186
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• 2017

This study is intended to provide navigator with specific information necessary to assist in the avoidance of collision and in operation of ships to evaluate the maneuverability of research vessel Jera. Authors carried out full-scale sea trials for turning test, zig-zag test, and spiral test at actual sea-going condition, which were performed on starboard and port sides with 10-20 rudder angle at service speed of 10 knots. The turning circle was much different at both of the turning of port and starboard which was longer at the starboard than at the port. In the zig-zag test results, the port and starboard was $10^{\circ}$ the first and second overshoot angles were $6.0^{\circ}$, $5.8^{\circ}$ and $6.3^{\circ}$, $7.1^{\circ}$ respectively and the first overshoot angles were $16.4^{\circ}$, $17.6^{\circ}$ when using $20^{\circ}$. Her maneuverability index T and N can be easily determined by using an analogue computer with the data obtained from the zig-zag tests where K is a constant representing the turning ability and T is a constant representing her quick response. In the zig-zag tests under $10^{\circ}$ or $20^{\circ}$ at rudder angle, the value K is 0.149. 0.123 sec- and T is 11.853 and 6.193 sec and angular velocity is $0.937^{\circ}/sec$ and $1.636^{\circ}/sec$. In the spiral test, the loop width was unstable at $+0.51^{\circ}$ and $-1.19^{\circ}$ around the midship of rudder, but the tangent line at $0^{\circ}$ was close to vertical. From the sea trial results, we found that she did comply with the present criterion in the standards of maneuverability of IMO.