• Journal of Digital Convergence
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• v.12 no.11
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• pp.373-378
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• 2014

The technology of direction finding is very important to make high position fixing accuracy. TDOA(time difference of arrival) direction finding technology is a high accuracy technology and is used in RF system from 1990. The principle of TDOA is to receive an emitter signal with two antennas, measure the time difference of received signal and then convert the time differences to azimuth angle. For high DF(direction finding) accuracy long basis line and high SNR at receiving system are needed. The DF accuracy and position fixing accuracy are simulated with different SNRs and antenna base lines. We obtain the DF accuracy of $0.51^{\circ}$ at $0^{\circ}$ incident azimuth angle in case of 50m base line and 40dB SNR.

• Journal of Advanced Navigation Technology
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• v.15 no.5
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• pp.742-748
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• 2011

G-File on the position of the photo shoot pictures with built-in picture file to the user, the location and orientation of the image files using the data refers to the [1]. G-File is to store photo files, photo files and receiving means for receiving input, and picture files, photos and location information extracted by separating the subject's location information with location information and location analysis by means of the corresponding coordinates on the map including the location indicated in the guide means is characterized in that. In this paper, the G-File on the location information stored in the algorithm that can be managed is proposed. G-File on the algorithm used to manage the information to the user, G-File management is to provide convenience.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.46 no.5
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• pp.38-43
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• 2009

We derive an equation that predicts the induced voltage across the receiving terminals of the three-coil head of a metal detector using a magnetic vector potential approach. We also derive an equation that relates the change of the impedance of the transmitting coil to the properties of the metal. We utilize the results to obtain the optimum spacing between the driving and the receiving coils at which the maximum induced voltage is attained. Further, we determine the position of the metallic object where the voltage reaches its peak. We verify our work by comparing the results with those of a previous work.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.2
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• pp.199-210
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• 1998

It is very important to analyze and predict the propagation characteristics of LEO communication satellite at the service area using computer simulation. In this paper, the propagation characteristics of a satellite communication system are analyzed using ray tracing technique. We predicted the receiving environment and obtain the delay profile and total received power at each position using ray tracing method by changing both the azimuth and elevation angles after establishing the imaginary receiving space. The final goal of this paper is to analyze and understand the wave propagation characteristics of the satellite communication network about 2 GHz frequency band. The prediction method presented in this paper may help us to design satellite transceiver system and to construct a satellite communication network.

• Journal of the Korean Society for Nondestructive Testing
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• v.34 no.3
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• pp.211-219
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• 2014

Closed cracks are difficult to detect using conventional ultrasonic testing because most incident ultrasound passes completely through these cracks. Nonlinear ultrasound inspection using sub-harmonic frequencies a promising method for detecting closed cracks. To implement this method, a sub-harmonic phased array (PA) is proposed to visualize the length of closed cracks in solids. A sub-harmonic PA generally consists of a single transmitter and an array receiver, which detects sub-harmonic waves generated from closed cracks. The PA images are obtained using the total focusing method (TFM), which (with a transmitter and receiving array) employs a full matrix in the observation region to achieve fine image resolution. In particular, the receiving signals are measured using a laser Doppler vibrometer (LDV) to collect PA images for both fundamental and sub-harmonic frequencies. Oblique incidence, which is used to boost sub-harmonic generation, inevitably produces various surface waves that contaminate the signals measured in the receiving transducer. Surface wave interference often degrades PA images severely, and it becomes difficult to read the closed crack's position from the images. Various methods to prevent or eliminate this interference are possible. In particular, enhancing images with signal processing could be a highly cost-effective method. Because periodic patterns distributed in a PA image are the most frequent interference induced by surface waves, spatial frequency filtering is applicable for removing these waves. Experiments clearly demonstrate that the spatial frequency filter improves PA images.

• 한국해양학회지
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• v.30 no.1
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• pp.27-38
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• 1995

For the study of oceanic surface current, this work presents a system design which is composed of three parts, a Global Positiong System(GPS) unit, a transmitter with radio frequency (RF) modem and an antenna which are housed in a plastic spherical buoy, and computerised of VHF receiving system. The key idea for this study is to employ a commercially available GPS on a drifting buoy and to utilize the receiver position information from the buoy in determining the Lagrangian motion of surface ocean waters. Great efforts has been paid to the system design which would demand several points in harsh conditions common in the sea surface, that is power supply problems housed inside of a plastic buoy, optimizing transmitting radio frequency which limits transmitting distance to a receiving station. for all these difficulties, the system appears to be promising in future oceanic applications and is considered to economical compared to ARGOS drift buoy which is being used by commercial base. We believe that the system needs to be improved in terms of several aspects such as a longer transmitting distance, a power supply and software. for the test experiments in situ, the system has employed off the coast of Ku Ryong Po int the southeast part of Korea and successfully collected the surface current data. The results are presented for two cases from 21 to 31, March 1994 and 21 to 25, June 1994 in terms of current statistics and trajectories of drifting buoys.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.2
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• pp.923-927
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• 2013

Objective: This work aims to investigate the therapeutic regimen of brain metastatic cancers and the relationship between clinical features and prognosis. Methods: Clinical data of 184 patients with brain metastatic cancers were collected and analysed for the relationship between survival time and age, gender, primary diseases, quantity of brain metastatic foci, their position, extra cranial lesions, and therapeutic regimens. Results: The average age of onset was 59.1 years old. The median survival time (MST) was 15.0 months, and the patients with breast cancer as the primary disease had the longest survival time. Females had a longer survival time than males. Patients with meningeal metastasis had extremely short survival time. Those with less than 3 brain metastatic foci survived longer than patients with more than 3. The MST of patients receiving radiotherapy only and the patients receiving chemotherapy only were all 10.0 months while the MST of patients receiving combination therapy was 16.0 months. Multiple COX regression analysis demonstrated that gender, primary diseases, and quantity of brain metastatic foci were independent prognostic factors for brain metastatic cancers. Conclusions: Chemotherapy is as important as radiotherapy in the treatment of brain metastatic cancer. Combination therapy is the best treatment mode. Male gender, brain metastatic cancers originating in the gastrointestinal tract, more than 3 metastatic foci, and involvement of meninges indicate a worse prognosis.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.1
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• pp.7-14
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• 2013

Presently, there are many different technologies used for position detection. However, as signal-receiving devices operating in different locations must detect the precise position of objects located at long distances, it is essential to know the precise time at which an object's or a user's terminal device sends a signal. For this purpose, the existing time of arrival (ToA) technology is not sufficiently reliable, and the existing time difference of arrival (TDoA) technology is more suitable. If a TDoA-based electric surveillance system and other tracking devices fail to achieve precise time-synchronization between devices with separation distance operation, it is impossible to obtain correct TDoA values from the signals sent by the signal-receiving devices; this failure to obtain the correct values directly affects the location estimation error. For this reason, the technology for achieving precise time synchronization between signal-receiving devices in separation distance operation, among the technologies previously mentioned, is a core technology for detecting TDoA-based locations. In this paper, the accuracy of the proposed time synchronization and the measurement error in the TDoA-based location detection technology is evaluated. The TDoA-based location measurement error is significantly improved when using the proposed method for time-synchronization error reduction.

• Journal of Distribution Science
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• v.18 no.1
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• pp.95-105
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• 2020

Purpose: Will more expensive gifts be more pleasurable and appreciated? This is a general expectation of gift-givers. According to the previous study on Americans (Flynn and Adams 2009), recipients tend to appreciate gifts regardless of their price. It indicates that there is an interaction effect between position (giving / receiving) and gift price. This study expands the previous study and aims to answer the following two questions: "Are such an interaction effect observed in Korean, too?" and "What types of people prefer expensive gifts?" Research design, data, and methodology: Study 1 of the current research repeated the Study 3 of Flynn and Adams (2009), with an iPod (high-priced gift condition) and a music CD (low-priced gift condition). That is, a 2 (gift price: high / low) x 2 (position: giver / receiver) between-group design was used. Study 2 used gift certificates of 100,000 won (high-priced gift condition) and 5,000-won gift (low-priced gift condition). Unlike the previous study that measured only one dependent variable (gratitude), this study added five more dependent variables in an attempt to exclude alternative explanations, such as endowment effects or emotional conflicts. This study also measured individualism / collectivism, face sensitivity, and materialism to explore the types of people who prefer expensive gifts. Results: The interaction effect between gift price and position on the level of appreciation was not significant. Meanwhile the main effect of gift price and of position were significant. The gift-recipient was more appreciative than the gift-givers' expectation regardless of the price of gifts. To investigate individual differences, individualism/collectivism, face sensitivity, and materialism were examined, but none of these variables were significantly related to the preference for expensive gifts. Respondents who received gift certificates in Study 2 were less grateful than those who received iPods or music CDs in Study 1. Conclusions: This study found that Koreans tend to be more grateful if they receive expensive gifts, in contrast to the Flynn and Adams (2009)'s study with Americans. In addition, gift-recipients appreciated more than givers' expectation and were more grateful when they received tangible products rather than gift certificates.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.364-367
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• 2007

We combined CC2431(Chipcon, Norway), as the platform for the Indoor Location Tracking, which follows Zigbee/IEEE802.15.4 standards in RSSI (Received Signal Strength Indicator) and Base Station Node and then, embodied Indoor Location Tracking System. CC2431 is composed of the Reference Node that transfer its current position at the designated place and the Blind Node. The Blind node receives the current position(X and Y coordinates) of the Reference Node fields which are being contiguous and also, calculates its current position and transfers it to the Base Station Node. The base station node is used for receiving the current position of blind node and passing its data to the PC as a gateway. We can make sure where is the Blind Node not only from the out-of-the-way place of the server side but from the outside in a real-time.