• Journal of the Korean Society for information Management
• /
• v.20 no.1
• /
• pp.145-163
• /
• 2003

An indexing language were studied to construct the sentences and paragraphs providing system aided to write a Korean or English composition. The indexing language includes the index terms like noun, predicate, and adverb. and also various index symbols. The subject name and the keyword Included the symbols, which Indicate the connectives between clauses in a sentence, is used as the access point. The search results show this system will be effective with large database and developed retrieval methods.

• Journal for History of Mathematics
• /
• v.31 no.3
• /
• pp.127-150
• /
• 2018

In spite of important researches and translational works of the Joseon mathematical treatises in the 80's and on, these results were almost out of reach to the school teachers as well as students due to the antiquity of their contents and the terms used. In order to make our traditional mathematics approachable to the middle and high school students, it will be educationally meaningful to reinterpret them tuned at the student's level using modern terminology and symbols. In this study, we reinterpreted 9 problems from Cheukryang Dohae, which is one of the representative mathematical books of Joseon Dynasty. We used the terminology and symbols from the school curriculum. We also reconstructed two of them using modern metrologies adapted to modern situations adding illustrations and photos, so that they are useful at the teaching site.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.23 no.7
• /
• pp.1824-1830
• /
• 1998

In this paper, we investigate a noise reduction scheme, based on the inherent characteristic of an orthogonal sequence. The modulated orthogonal code generates sequences of length $N^{2}$ from N information symbols. Using the amplitudes of the received symbols, we first estimate the location of the smallest amplitude noise. Then the noise is reduced by the suggested system. The performance of the scheme is confirmed by computer simulation results.

• Journal of Korea Society of Digital Industry and Information Management
• /
• v.6 no.2
• /
• pp.225-231
• /
• 2010

This paper proposes the strategy of ladder trades in a symbol pool and simulates a performance of it on the Multicharts' system trading tool. The ladder trading strategy is based on a multi-entry strategy which is efficient for several symbols. A symbol pool is composed of verified stocks comprising KOSPI200 and 17 symbols are selected for an examination which equity is over 10 billion. From July to December in 2009, optimum parameters are searched and the results are delta is 4% and ladder is 5. When those parameters are adopted, the profit is 1,000,000 won as a single trade and the number of trade is 188. The next study is to modify a ladder shape for increasing probability and to find the difference of optimum parameters according to trading months.

• Korean Journal of Child Studies
• /
• v.23 no.6
• /
• pp.81-101
• /
• 2002

This study examined the effects of a geographic experiential activity program on the ability to represent and to read maps(directions, perspectives, and symbols). The subjects were 44 5-year-old kindergarten children assigned to an experimental or a control group, with 22 children in each group. The geographic experiential activity program was developed and applied to the experimental group for 4 weeks. Results indicated that the experimental group was higher in reading and representing maps than the control group. Through the geographic experiential activity program, children came to be concerned about their living space, to be able to read and comprehend a simple map, and to represent a basic map with the use of directions, perspectives, and symbols.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.1A
• /
• pp.10-15
• /
• 2010

This paper proposes a practical method for AGC (Automatic Gain Control) in WiBro (Wireless Broadband) AT (Access Terminal) system. Downlink packets in this system consist of preamble symbols for AGC, AFC (Automatic Frequency Control) and other purposes and data symbols for traffic transmission. In this paper we compare theoretical BER (Bit Error Rate) performance with simulation results and produce optimum parameters for AGC in this system. And we propose an efficient AGC scheme before synchronization.

• ETRI Journal
• /
• v.37 no.5
• /
• pp.922-928
• /
• 2015

A novel peak-to-average power ratio (PAPR) reduction method is proposed for single-carrier frequency-division multiple access (SC-FDMA) signals. The proposed method deliberately distorts the amplitude values of a few of the complex modulated symbols that cause peaks beyond a predetermined threshold in the samples of the output signal. The method then marks the location indices of the distorted symbols by using a pilot block at the transmitter without transmitting side information. At the receiver, the method is then able to recover the distorted amplitude values through the marked location indices. Computer simulation results show that when compared to conventional SC-FDMA signals, the proposed scheme can effectively reduce the PAPR of SC-FDMA signals with asymptotically consistent bit error rate (BER) performance.

• ETRI Journal
• /
• v.36 no.4
• /
• pp.564-571
• /
• 2014

Sphere decoding (SD) for multiple-input and multiple-output systems is a well-recognized approach for achieving near-maximum likelihood performance with reduced complexity. SD is a tree search process, whereby a large number of nodes can be searched in an effort to find an estimation of a transmitted symbol vector. In this paper, a simple and generalized approach called layer pruning is proposed to achieve complexity reduction in SD. Pruning a layer from a search process reduces the total number of nodes in a sphere search. The symbols corresponding to the pruned layer are obtained by adopting a QRM-MLD receiver. Simulation results show that the proposed method reduces the number of nodes to be searched for decoding the transmitted symbols by maintaining negligible performance loss. The proposed technique reduces the complexity by 35% to 42% in the low and medium signal-to-noise ratio regime. To demonstrate the potential of our method, we compare the results with another well-known method - namely, probabilistic tree pruning SD.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.33 no.3A
• /
• pp.277-285
• /
• 2008

We previously proposed an Orthogonal Code Hopping Multiplexing (OCHM) scheme for statistical multiplexing on a synchronous downlink. OCHM enables a large number of users to share a limited number of code channels through statistical multiplexing. We here improve the performance of OCHM by prioritizing encoded symbols according to their importance using both the conventional code division and the previously proposed code hopping multiplexing schemes. Prioritization is useful for channel coding schemes with different levels of importance for encoded symbols such as turbo-codes. Scheme performance is evaluated by simulation in terms of the required Eb/N0 for a 1% block error rate.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.3
• /
• pp.648-653
• /
• 2011

We propose a new frequency offset estimation technique for multiband orthogonal frequency modulation (MB-OFDM) based ultra wideband (UWB) systems. The proposed frequency offset estimation technique is related to the scheme of Schmidl for channel model 1 (4-1Om NLOS, rms. delay =14.3ns.) using more than two symbols and with alternate symbols. Variance of frequency offset estimate obtained from the proposed frequency offset estimation technique approaches very nearing to Cramer Rao Lower Bound (CRLB) in an AWGN channel. BER performance of the proposed technique is also presented.