• Journal of Navigation and Port Research
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• v.28 no.3
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• pp.207-211
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• 2004

The final goal of this research is to establish the relative dangerousness D/B for factors on seakeeping performance. This D/B is essential to develope the seakeeping performance evaluation system built-on-ship. The system is composed of the apparatus for measuring a vertical acceleration to be generated by the ship's motions, computer for calculating the synthetic seakeeping performance index and monitor for displaying the evaluating diagram of navigational safety of ship. In this paper, a methodology on the establishment of the relative dangerousness D/B for factors on seakeeping performance is presented by a numerical simulations, playing an important role on the algorithm of the program for calculating the synthetic seakeeping performance index. Finally, It is investigated whether the relative dangerousness D/B can be realized an accurate values according to the loading conditions, weather conditions, wave directions end present ship's speed of a model ship.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.1168-1171
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• 2003

In contrast to a conventional transformer, the flat transformer is made using a number of small ferrite cores. Two cores for transformer and one core for inductor, which composed one module. Many modules can be connected together to form a flat matrix transformer. This structural arrangement eliminates the single hot spot problem in conventional transformers and permits high current density pertains at high frequency. In this study, the ferrite magnetic cores of Mn-Zn system for the Flat transformer were manufactured and the electrical and magnetic characteristics of its tested. The power loss of sample FO2(Mn-Zn ferrite) sintered at $1350^{\circ}C$ was $350kW/m^3$ in test conditions of 250kHz, 200mT and $100^{\circ}C$, which showed the good power loss property in high frequency. The power loss of FO2 samples has been studied as a function of magnetic flux density and frequency. Steinmetz exponent was 2.82 at 250kHz and 2.73 at 500kHz. These results illustrated the switching of power loss mechanism in ferrite core from hysteresis losses to eddy current losses or others.

• Journal of the Korea Convergence Society
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• v.9 no.7
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• pp.63-68
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• 2018

Research on smart farms centering on greenhouse cultivation is actively under way due to the decrease in agriculture population and aging, but in the case of vegetables such as vegetables, outdoor cultivation is 70%. Therefore, there is a need to improve productivity and prevent soil contamination by automating, cultivating, and intelligentizing the outdoor cultivation of agriculture crops. In this paper, we show the case of establishing a outdoor production system using the Internet of things and define the environmental variables in the outdoor production system. By measuring soil temperature, water content, electrical conductivity and acidity through sensors, LoRa communication module transmits the information to the outdoor production system. The outdoor production system controls the amount of fertilizer and the volume of water based on this sensor data. We have developed a system that manages a wide range of crops using LoRa technology, which is a suitable communication method for cultivating crops, and manages production volume and sales performance.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.12
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• pp.57-63
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• 2016

This paper describes implementation of the RF frequency synthesizer with $0.18{\mu}m$ silicon CMOS technology being used as an application of the IEEE802.15.4g SUN sensor node transceiver modules. Design of the each module like VCO, prescaler, 1/N divider, ${\Delta}-{\Sigma}$ modulator, and common circuits of the PLL has been optimized to obtain high speed and low noise performance. Especially, the VCO has been designed with NP core structure and 13 steps cap-bank to get high speed, low noise, and wide band tuning range. The output frequencies of the implemented synthesizer is 1483MHz~2017MHz, the phase noise of the synthesizer is -98.63dBc/Hz at 100KHz offset and -122.05dBc/Hz at 1MHz offset.

• Membrane and Water Treatment
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• v.1 no.3
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• pp.207-214
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• 2010

Approximately 80% of water used in urban areas reappears as municipal wastewater (MWW). Reclamation of MWW is an attractive proposition under the present scenario of water stressed cities in India. In this paper, we attempted to reclaim MWW using lab-scale hollow- fiber (HF) membrane modules for possible reuse in non-potable applications. Experiments were conducted to evaluate the efficiency of virgin HF ($M_1$) and modified HF ($M_2$) modules. The $M_2$ module consists of HF modified with a skin layer formed through interfacial polymerization of m-phenylenediamine with trimesoyl chloride (MPD-TMC). The molecular weight cut-off (MWCO) of $M_1$ was 44000 g/mol and that of $M_2$ 10000 -14000 g/mol on the basis of rejection of polyethylene glycol. The combination of $M_1$ and $M_2$ modules was able to reduce concentrations of most of the pollutants in sewage and improved the treated water quality to the acceptable limits for non potable reuse applications. It is found that about 98-99% of the initial flux is recovered by the backwashing process, which was approximately two times in a month when operated continuously.

• Proceedings of KOSOMES biannual meeting
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• 2007.11a
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• pp.51-55
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• 2007

As for satellite programs, the multipurpose satellite 1(KOMPSAT-1) was successfully launched on Dec. 21, 1999 and operated for three years. It is still properly operated even though its life cycle was ended. The development of KOMPSAT-2 (Korea Multipurpose Satellite-2) is near completion and the development of KOMPSAT-3, KOMPSAT-5 and COMS (Communication, Ocean, Meterological Satellite) are proceeding swiftly. In KORDI(Korea Ocean Research and Development Institute), the KOSC (Korea Ocean Satellite Center) construction project is being prepared for acquisition, processing and distribution of sensor data via L-band from GOCI(Geostationary Ocean Color Imager) instrument which is loaded on COMS(Communication, Ocean and Meteorological Satellite); it will be launched in 2000. Ansan(the headquarter of KORDD has been selected for the location of KOSC between 5 proposed sites, because it has the best condition to receive radio wave. The data acquisition system is classified antenna and RF. Antenna is designed to be ${\emptyset}$ 9m cassegrain antenna which has 19.35 $G/T(dB/^{\circ}K)$ at 1.67GHz, RF module, is divided into LNA(Low noise amplifier) and down converter, those are designed to send only horizontal polarization to modem The existing building is re-designed and classified for the KOSC operation concept; computing room, board of electricity, data processing room, operation room Hardware and network facilities have been designed to adapt for efficiency of each functions. The distribution system which is one of the most important systems will be constructed mainly on the internet, and it is also being considered constructing outer data distribution system as a web hosting service for to offering received data to user under an hour.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.6
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• pp.745-753
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• 2016

This paper presents a fully synthesizable low power interconnect bus for millimeter-scale wireless sensor nodes. A segmented ring bus topology minimizes the required chip real estate with low input/output pad count for ultra-small form factors. By avoiding the conventional open drain-based solution, the bus can be fully synthesizable. Low power is achieved by obviating a need for local oscillators in member nodes. Also, aggressive power gating allows low-power standby mode with only 53 gates powered on. An integrated wakeup scheme is compatible with a power management unit that has nW standby mode. A 3-module system including the bus is fabricated in a 180 nm process. The entire system consumes 8 nW in standby mode, and the bus achieves 17.5 pJ/bit/chip.

• Journal of Korea Multimedia Society
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• v.10 no.3
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• pp.335-347
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• 2007

VoIP (Voice over IP) is a technology to transport video and voice traffic over IP networks such as Internet. Today, the VoIP technology is viewed as the right choice for providing voice, video, and data communication among various terminals over the next generation network. This paper discusses a multipoint VoIP implementation with end-point mixing model which can support multipoint conference without a conference bridge. The multipoint VoIP is implemented with SIP (Session Initiation Protocol), and supports STUN (Simple Traversal of UDP Through NATs) since it works in an asymmetric NAT (Network Address Translator) environment. The characteristics of this paper are as follows. It is possible that all terminals in the hierarchical conference don't receive the duplicated media information because we use the end-point mixing model with the new media processing module. And, the paper solves the problem that the hierarchical conference session should be separated into several sessions when a mixing terminal terminates the hierarchical conference session.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.593-599
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• 2007

PC based DVR replaces existing analog CCTV system therefore expands the field and DVR is used for monitoring and security so it requires exact time(clock). But DVR system can't maintains exact clock causing several reasons. For providing exact time information we should use additional system. For economical and usable environment, using GPS system is most suitable suggested solution than use WAN(Wide Area Network). Therefore in this paper for analysis the result of PC based DVR's system clock using GPS system, 1) clock source receiving module that receives the clock form GPS satellite and 2) GPSW H/W units that provide clock source to PC Based DVR 3)Daemon software named PCSW which adjust PC's clock so system could reduced the clock difference with UTC clock and measured the result.

• The KIPS Transactions:PartC
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• v.11C no.1
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• pp.39-46
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• 2004

It has been happening to transfer not only the general information but also the valuable information through the universal Internet. So security accidents as the expose of secret data and document increase. But we don't have stable structure for transmitting important data. Accordingly, in this paper we intend to use network based Intrusion Detection System modules and detect the extrusion of important data through the network, and propose and design the method for investigating concealment data to protect important data and investigate the secret document against the terrorism. We analyze the method for investigating concealment data, especially we use existing steganalysis techniques, so we propose and design the module emphasizing on the method for investigating stego-data in E-mail of attach files or Web-data of JPG, WAVE etc. Besides, we analyze the outcome through the experiment of the proposed stego-data detection system.