• Journal of Korean Society for Geospatial Information Science
• /
• v.3 no.2 s.6
• /
• pp.15-28
• /
• 1995

The GPS positioning involves not only 'natural' errors associated with the satellites position errors, refraction of EM wave in the ionosphere, etc., but also 'artificial' errors associated with the operation of S/A (Selective Availability). In this paper, we present the principles, accuracies and applicabilities of our personal DGPS method, which employs the position-correction method on the GPS positionings data collected at the reference and the remote sites. The essential requirement of our DGPS method is that two GPS receivers should utilize the identical Navstar satellites at the same time. The positioning error (1 drms) of the stand-alone GPS is of an order of a few tens meters, while that of horizontal position by our DGPS method is about 1m and that of vertical position is about 2m We applied out DGPS technique in positioning moving objects, and obtained satisfactory results in tracking the trajectories of a car on the road and the those of drifters in the sea.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.3A
• /
• pp.282-290
• /
• 2006

In this paper, we propose an enhanced Timing Estimator algorithm for 2.45GHz LR-WPAN receiver. Because an expensive and highly efficient oscillator can't be used for low-cost implementation, a Timing Estimator algorithm having stable operation in the channel environment with center frequency tolerance of 80 ppm is required. To enhance the robustness to frequency offset and the stability of receiver performance, multiple delay differential filter is adopted. By utilizing the characteristic that the correlation result between the output signal of Multiple delay differential filter and reference signal is restricted on the In-phase part of the correlator output, a coherent detection scheme instead of the typical noncoherent one is adopted for Timing Estimator. The application of the coherent detection scheme is suitable for LR-WPAN receiver aimed at low-cost, low-power, and low-complexity, since it can remove performance degradation due to squaring loss of I/Q squaring operation and decrease implementation complexity. Computer simulation results show that the proposed algorithm achieved performance improvement compared with the differential detection-based noncoherent scheme by 2dB in average.

• Journal of Biomedical Engineering Research
• /
• v.19 no.4
• /
• pp.351-360
• /
• 1998

Digital gamma camera has many advantages over analog gamma camera. These include convenient quality control, easy calibration and operation, and possible image quantitation which results in improving diagnostic accuracies. The digital data can also be utilized for telemedicine and picture archiving and communication system. However, many hospitals still operate analog cameras and have difficult situation to replace them with digital cameras. We have studied a feasibility of digitalizing an analog gamma camera into a digital camera using Gamma-PF interface board. The physical characteristics that we have measured are spatial resolution, sensitivity, uniformity, and image contrast. The patient's data obtained for both analog and digital camera showed very similar image quality. The results suggest that it may be feasible to upgrade an analog camera into a digital gamma camera in clinical environments.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.25 no.4
• /
• pp.418-425
• /
• 2014

This paper presents a Ku-Band Doppler Radar System to measure respiration and heart rate. It was measured by using simultaneous radar and ECG(Electrocardiogram). Arctangent demodulation without dc offset compensation can be applied to transmitted I/Q(In-phase & Quadrature-phase) signal in order to improve the RMSE(Root Mean Square Error) about 50 %. The power leaked to receiving antenna from the transmitting antenna is always generated because of continuously opening the transceiver of CW(Continuous Wave) Doppler radar. As the output power increase, leakage power has an effect on the SNR(Signal-to-Noise Ratio) of the system. Therefore, in this paper, leakage cancellation technique that adds the signal having the opposite phase of the leakage power to the leakage power was implemented in order to minimize the decline of receiver sensitivity. By applying the leakage cancellation techniques described above, it is possible to measure the heart rate and respiration of the human at a distance of up to 35 m. the heart rate of the measured data at a distance of 35 m accords with the heart rate extracted from the ECG data.

• Ecology and Resilient Infrastructure
• /
• v.8 no.1
• /
• pp.32-43
• /
• 2021

Multichannel automated chamber systems (MCACs) were developed for the continuous monitoring of soil CO2 efflux in forest ecosystems. The MCACs mainly consisted of four modules: eight soil chambers with lids that automatically open and close, an infrared CO2 analyzer equipped with eight multichannel gas samplers, an electronic controller with time-relay circuits, and a programmable logic datalogger. To examine the stability and reliability of the developed MCACs in the field during all seasons with a high temporal resolution, as well as the effects of temperature and soil water content on soil CO2 efflux rates, we continuously measured the soil CO2 efflux rates and micrometeorological factors at the Nam-san experimental site in a Quercus mongolica forest floor using the MCACs from January to December 2010. The diurnal and seasonal variations in soil CO2 efflux rates markedly followed the patterns of changes in temperature factors. During the entire experimental period, the soil CO2 efflux rates were strongly correlated with the temperature at a soil depth of 5 cm (r2 = 0.92) but were weakly correlated with the soil water content (r2 = 0.27). The annual sensitivity of soil CO2 efflux to temperature (Q10) in this forest ranged from 2.23 to 3.0, which was in agreement with other studies on temperate deciduous forests. The annual mean soil CO2 efflux measured by the MCACs was approximately 11.1 g CO2 m-2 day-1. These results indicate that the MCACs can be used for the continuous long-term measurements of soil CO2 efflux in the field and for simultaneously determining the impacts of micrometeorological factors.

• Archives of design research
• /
• v.11 no.2
• /
• pp.129-140
• /
• 1998

This study aimed to grqJe for and present guideline roodel when the qJerator of domestic small manufacturing industry try to introch1ce the first industrial design by easier and more effective method. As the method of study, first of aiL examined the necessary of introducing industrial design throogh coosidering about the role and importance of small business. And next, analysed and examined the result of researching by enquete that is for qJerators of cbnestic small business. As a result, preconditioos for effective introducing industrial design were found. And, based 00 the preconditioos that were found through researching by enquete, examined the approachable introducing methods. Finally, set up the effectivable introducing methods of industrial design for doo1estic small manufacturing industry as a graphical model. As a result of study, First, the operator of small business who try to introduce industrial design needs to be well aware of these six cooditions as a prenise of effective awroach.1) coosciousness of role and versus a nation and a people of own industry Cereative 2) managing coosideratim and examinatim of a necessity of introducing industrial design as a cata1yst 3) A certain understanding aIntt essence and value of industrial design 4) Study and examinatim about a case of sucessful introducing industrial design arxl common introducing method of small business.5) Befarehand examinatim of introducing method making use of professional design organization and consultatim wicket 6) Prodent examination about the appointlrent puprpose, method of designer and infonmtion about designer. Second, as the position of small bnsiness that introduce industrial design fur the first time, it is confirmed that the aroroach going with introducing types - preliminary introducing, partitial introducing, regular introducing, whole industry level introducing - considered necessity rate of introducing industrial design and introducing range at the same time. This method is able to approach step by step, but it is confinmed that there is a characteristic in being able to select the method freely, and understanding easily for being coostructed visual form.

• Journal of Korea Multimedia Society
• /
• v.2 no.3
• /
• pp.329-338
• /
• 1999

In this paper we propose a WATM MAC protocol called DTDD/PS (Dynamic Time Division Duplex using Poll/Select scheme). The idea of the DTDD/PS protocol is based that a radio cell is considered as queueing system. The MAC controller in base station is charged in coordinating terminals for the QoS requirement from each terminal. For that reason, terminals send it's own dynamic parameter represented its status, and controller controls the access of terminals and assigns time slots dynamically using received parameters. Therefore this system can satisfy the QoS of real-time service in wireless environments. To evaluate DTDD/PS protocol simulations are executed. In 25Mbps channel capacity, the voice and data coexist traffic situation, as the total number of terminal is increased, the delay of data terminals is increased rapidly. But the case of only increasing data terminals, the number of supported voice terminals is not varying. Therefore we can expect that DTDD/PS protocol can applied to multimedia traffic effectively.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.3 no.2
• /
• pp.11-17
• /
• 2000

The drift and movement of oil slick in the sea are closely related to the flows at the sea surface (at 0m depth) because specific gravity of an oil is lighter than that of sea water. As an effort toward a development of realistic model for oil spill drift on the sea surface, a study on sea surface wind-induced drift (skin drift) at 4 coastal regions of Korea was carried out. In this study, skin drifts were inferred from difference between the flow at the sea surface and that in underwater (at 1.5m depth). The average speed of skin drift in our experiments was 2.9% of wind speeds and the average direction of skin drift to wind was deflected to the right by 18.6°. The results of this experiment were used in the modelling of the skin drift as a prompt response of time-variable wind. The modelled skin drift, which corresponds to observed wind, successfully reproduced the observed trajectories of sea surface flows.

• Journal of Internet Computing and Services
• /
• v.4 no.5
• /
• pp.11-19
• /
• 2003

Since B2C(Business to Customer) from which e-commerce had originated was replaced by B2B, e-Business has shown fast growth so fa., Recently, e-Procurement by l:n concept is on the development as self-purchase system associated with their own ERP In many conglomerates in the Korean market. However, in order to vitalize e-Biz in the plant industry, we need to set up e-marketplaces where many sellers and buyers can meet each other at the same time, which has become the essential part for success as an expanded business model. In this paper, we expect that the foundation for e-transformation in the plant industry is set up by developing Purchase Process System and related modules as the prerequisite for e-Biz in the plant industry, and this report will provide an exemplary model for e-commerce. The Purchase Process System consists of 1) e-Purchasing Module that manages bidding and contract information based on quotation inquiry, 2) e-Expediting Module that manages information to guarantee the on-time delivery, 3) e-Certification Module that controls user authentification, 4) e-Basic Module that manages the bulletin boards, Q&A, etc.

• Journal of the Korean Ceramic Society
• /
• v.41 no.8
• /
• pp.599-604
• /
• 2004

The LTCCs (Low-Temperature Co-fired Ceramics) are very important for electronic industry to build smaller RF modules and to fulfill the necessity for miniaturization of devices in wireless communication industry. The dielectric materials with sintering temperature $T_{sint}$＜90$0^{\circ}C$ are required. In this study, BaO-N $d_2$ $O_3$-Ti $O_2$ (BNT ： 20∼40 wt％) for ceramic materials and L $a_2$ $O_3$- $B_2$ $O_3$-Ti $O_2$ (LBT ： 80∼60 wt％) for crystallizable glasses were used. The glass/ceramic composites were investigated for sintering behavior, phase evaluation, densities, interface reaction and microwave dielectric properties. It was found that the addition LBT glass frist significantly lowered the sintering temperature to below 90$0^{\circ}C$ and the densification with increasing addition LBT glass frist developed rapidly which was meant to be namely 90％ of relative density. The sintered bodies ekhibited applicable dielectric properties, namely 15 for $\varepsilon$$_{r}$,, 10000 GHz for Q＊ $f_{0}$. The results suggest that the composites have good potential as a new candidate for LTCC materials.