• Proceedings of the Korea Contents Association Conference
• /
• 2004.05a
• /
• pp.423-428
• /
• 2004

In this paper, STBC (Space Time Block Code) is applied to the WB system and frequency repeated diversity is used to get the 4-th order space time diversity gain. The performance of が STDB-OFDM system is analyzed by computer simulation. As a result of simulation, proposed W system can reduce the complexity that is introduced by increasing number of transmit antenna and show the same performance of 4 antennas with only using 2. Proposed system shows the enhancement of 7.1 dB compared to the general UWB OFDM and 1.9 dB compared to UWB STBC-OFDM.

• Journal of Surface Science and Engineering
• /
• v.43 no.3
• /
• pp.154-158
• /
• 2010

Numerical analysis is done to investigate the effects of pulse bias on the plasma processing characteristics like ion doping and ion nitriding by using fluid dynamic code with a 2D axi-symmetric model. For 10 mTorr of Ar plasma, -1 kV of pulse bias was simulated. Maximum sheath thickness was around 20 mm based on the electric potential profile. The peak electron temperature was about 20 eV, but did not affect the averaged plasma characteristics of the whole chamber. Maximum ion current density incident on the substrate was 200 $A/m^2$ at the center, but was decreased down to 1/10th at radius 100 mm, giving poor radial uniformity.

• Journal of Communications and Networks
• /
• v.17 no.6
• /
• pp.622-633
• /
• 2015

The coexistence among different systems is a major problem in communications. Mutual interference between different systems should be analyzed and mitigated before their deployment. The paper focuses on two aspects that have an impact on the system performance. First, the coexistence analysis, i.e. evaluating the mutual interference. Second aspect is the coexistence techniques, i.e. appropriate system modifications that guarantee the simultaneous use of the spectrum by different technologies. In particular, the coexistence problem is analyzed between ultra-wide bandwidth (UWB) and narrow bandwidth (NB) systems emphasizing the role of spectrum sensing to identify and classify the NB interferers that mostly affect the performance of UWB system. A direct sequence (DS)-time hopping (TH) code design technique is used to mitigate the identified NB interference. Due to the severe effect of Narrowband Interference on UWB communications, we propose an UWB transceiver that utilizes spectrum-sensing techniques together with mitigation techniques. The proposed transceiver improves both the UWB and NB systems performance by adaptively reducing the mutual interference. Detection and avoidance method is used where spectrum is sensed every time duration to detect the NB interferer's frequency location and power avoiding it's effect by using the appropriate mitigation technique. Two scenarios are presented to identify, classify, and mitigate NB interferers.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.37 no.1
• /
• pp.44-51
• /
• 2000

We have analyzed optical matched filters considering the third order signals in the optical code division multiple access (CDMA) system based on optical series coupler access encoder (SCAE) and series coupler access decoder (SCAD). In previous studies, the performance evaluation of the optical CDMA system using SCAE and SCAD was not sufficiently accurate because they analyzed system performance only considering the first order signals. Since optical SCAE and SCAD intrinsically have high order signals of various patterns as the number of coupler increases, they change auto- and cross-correlation intensities. Thus, it is necessary to investigate properties of the third order signals so that we may analyze the exact performance of system. In this paper, we mathematically interpret the optical signals up to the third order, and analyzed the effects of th third order signals on auto- and cross-correlation intensities. In result, as ${\alpha}$(coupling coefficient) value increases, the intensity of the third order signals increases. It is found that the peak to side-lobe ratio considering the third order signals is degraded by 3.75 dB at N(coupler number)=5 and ${\alpha}$=0.5. Also if threshold value in receiver is set by main-lobe peak of the first order signals, it is found that the number of users in an optical CDMA system is limited because the intensity peak of side-lobes is raised by the third order signals.

• Journal of Korean Library and Information Science Society
• /
• v.15
• /
• pp.113-151
• /
• 1988

The enumerative classification schemes do not represent the tiny mass of knowledge embodied in a article in a periodical or in a chapter or a paragraph of a book. But today's information centers regard a tiny spot of knowledge embodied in a article as a class. we call this micro-thought. But the enumerative classification are manual systems, it cannot be a n.0, pplied to the automation of classification. The purpose of this study is to build a general principle for the automatic book-classification which can be put to use in library operation, and to present a methodology of the automatic classification for the library. The methodology used is essentially theoretical, Published works by and about Ranganathan, especially 6th edition of the CC were studied, analyzed. The principle of automatic book classification derived from the analysis of colon classification and facet combinations. The results of this study can be summarized as follows ; (1) This study confined the fields of library science and agriculture. (2) This study represent a general principles for the automatic book classification of library science and agriculture. (3) Program flowcharts are designed as a basis of system analysis and program procedure in library science and agriculture. (4) The principles of the automatic classification in library, science is different from that of agriculture. (5) Automatic book classification can be performed by the principle of faceted classification, by inputting the title and subject code into a computer. In addition, the expected value from the automatic book-classification is as follows (1) The prompt and accurate of classification is possible. (2) Though a book is classified in any library, it can have same classification number. (3) The user can retrieve the classification code of a book for which he or she wants to search through dialogue with the computer. (4) Since the concept coordination method is employed, a tiny mass of knowledge embodied in a article in a periodical or in a chapter or a paragraph of a book can be represented as a class. (5) By performing automatic book-classification, the automation of library operation can be completed.

• Journal of the Society of Naval Architects of Korea
• /
• v.54 no.6
• /
• pp.522-529
• /
• 2017

Air gun shock system is used as an alternative energy source as part of the attempt to overcome the restrictions of economical expense and environmental damage, etc., due to the use of explosives for the UNDerwater EXplosion (UNDEX) shock test. The objectivity of this study is to develop the simulation technique of air gun shock test for the design of model-scale one for the near field non-explosive UNDEX test through its verification with full-scale SERCEL shock test result. Underwater blasting response analysis of full-scale air gun shock test was carried out using highly advanced M&S (Modeling & Simulation) system of FSI (Fluid-Structure Interaction) analysis technique of LS-DYNA code, and was verified by comparing its shock characteristics and behaviors with the results of air gun shock test.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.16 no.4 s.95
• /
• pp.351-358
• /
• 2005

In this paper, STBC(Space Time Block Code) is applied to the UWB system and frequency repeated diversity is used to get the 4-th order space time diversity gain. The performance of UWB STBC-OFDM system is analyzed by computer simulation. As a result of analysis, proposed UWB system can reduce the complexity that is introduced by increaing number of radiator and show the same performance of 4 antennas with that only using 2 radiator. This system at the $10^{-4}$ also shows the enhancement of $7.1\;\cal{dB}$ to the general UWB OFDM and $1.9\;\cal{dB}$ to UWB STBC-OFDM.

• Journal of Acupuncture Research
• /
• v.33 no.4
• /
• pp.109-119
• /
• 2016

Objectives : The aim of this study is to give a statistical basis for the characteristics of patients who received cooperative medical care after being referred from Western medical departments to the Department of Acupuncture and Moxibustion in a Korean medical hospital. Methods : The request records were searched for cooperative medical treatment at the Department of Acupuncture and Moxibustion in a Korean medical hospital between September 1st, 2011 and August 31, 2016, based on the Order Communication system(OCS). The records were reviewed and retrospectively analyzed according to the patient's general characteristics, the chief diagnosis code based on the 7th Korean standard classification of diseases(KCD-7) before and after the cooperative medical care in the Department of Acupuncture and Moxibustion, and the actual treatment measures which patients received as a result of the cooperative medical care. Results : Among the 2702 records, 1549 patients were included in the analysis. The male to female ratio was 1 : 1.17. Sexagenarians formed the highest age group and the number of patients whose age was over 50 was 1176(75.92 %). The surgery department requested the cooperative care from the department of Acupuncture and Moxibustion for the highest number of patients, 1194(77.08 %). When analysing specific medical departments, Neurosurgery, General Surgery, Neurology, Otorhinolaryngology, and Physical medicine and rehabilitation followed. The frequency of chief diagnosis code used before the cooperative medical care was in the order of I, C, G, S, and M code, from highest to lowest. The order of the codes after the cooperative medical care was the same. Acupuncture treatment was the most frequently-used measure after the cooperative medical care. Following were infrared, moxibustion, transfer, herbal acupuncture, cupping, electroacupuncture, and so on. Conclusion : This study provides a statistical basis for the demands placed on the Department of Acupunture and Moxibustion for cooperative medical care with the Western medical department. Based on the present condition of cooperative medical care, more preparation and effort is required for its activation.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.24 no.8A
• /
• pp.1141-1148
• /
• 1999

In this paper, an RRA_CDMA protocol is proposed for the integrated voice and data services in the cellular packet CDMA systems. The proposed protocol employs the RRA scheme. In the cellular CDMA systems, the backward logical channels are composed of time slots with multiple spreading codes per slot based on WB-TD-CDMA concept. When a voice terminal begins a talkspurt, it reserves one of the available spreading codes in the next slot and uses the reserved channel exclusively untill it ends the talkspurt. On th other hand, whenever a data terminal generates a packet, it selects an avaliable spreading code and transmits its packet. Throughout the results, it is shown that the system capacity increases in proportion to the number of spreading codes.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.3C
• /
• pp.237-244
• /
• 2006

I/Q phase unbalance caused by non-ideal circuit components is inevitable physical phenomenons and leads to performance degradation when we implement a practical coherent M-ary phase shift keying(M-PSK) demodulator. In this paper, we present an exact and general expression involving two-dimensional Gaussian Q-functions for the bit error rate(BER) of uniform M-PSK with I/Q phase unbalance over an additive white Gaussian noise(AWGN) channel. First we derive a BER expression for the k-th bit of 8, 16-PSK signal constellations when Gray code bit mapping is employed. Then, from the derived k-th bit BER expression, we present the exact and general average BER expression for M-PSK with I/Q phase unbalance. This result can readily be applied to numerical evaluation for various cases of practical interest in an I/Q unbalanced M-PSK system, because the one- and two-dimensional Gaussian Q-functions can be easily and directly computed using commonly available mathematical software tools.