Earticle

We propose a novel cooperative space?time line code (C-STLC) scheme to improve performance of a relay-assisted internet of things (R-IoT). The proposed C-STLC operates with fully distributed manner, where each relay IoT device (RID) attempts to decode the received signal from a source IoT device at the first hop and the RIDs, that succeeded decoding, send the STLC encoded signal based on their local channel state information (CSI) to a single access point (AP) at the second hop. Then, the AP decodes the received signals without CSI. As a main result, we mathematically analyze the outage probability (OP) of the proposed C-STLC scheme. It is shown that the proposed C-STLC significantly outperforms conventional cooperative relaying techniques in terms of the OP.

Liquid crystal-polymer composite(LCPC) films promising new materials for both projection displays and vision product. LCPC films consist of a continous liquid crystal phase embedded in a three- dimensional network of polymer matrix. The liquid crystal in these LC phases can be elecrtrically switched giving rise to an opaque scattering off-stats and a transparent, non-scatting on- stats. In this work. a premixture is composed of LC, UV-curable monomer and photonitiator. LCPC films are formed by photopolymerization induced phase separation from this premixture. In conclusion, structure and electro-optical properties of LCPC films strongly depends on the selection of monomer, LC content and curing rate.

Software applications have a huge and inseparable impact on our lives. The complexity of the applications increases rapidly to support high performance and multifunction. Accordingly, the cost model for applications is increasingly important. Line of Code (LOC) and Man-Month (M/M) as the cost model measure the quantitative sides of the applications. Unlike them, Function Point (FP) measures the functionalities of the application. FP is efficient for estimating qualitative characteristics, but it is restricted to measuring the cost of an application using the wireless data broadcast which can support any number of clients. In this paper, we propose, a Function Point model for Information services using wireles data Broadcast (FPIB) to measure the development cost of an application that serves using the wireless data broadcast environment. FPIB adopts critical parameters of the wireless broadcast environment and the complexity of them to measure effectively the cost developing the application. Through the evaluation comparing the proposed FPIB with FP, we reveal the effectiveness of the proposed FPIB.

전력선 통신 (PLC : Power Line Communication) 기술은 유선 액세스 네트워크 솔류션 중 높은 잠재력을 갖고 있는 후보로서 논의되고 있다. 본 논문에서는 PLC 채널에서 이중 이진 터보 부호 (DBTC : Double Binary Turbo Code) 성능에 대해 연구하였다. PLC 채널 환경을 만들기 위해 Bernoulli-Gaussian 잡음을 고려하였다. 시스템 성능은 비트 오류 확률 측면에서 분석되었다. 실험 결과로부터 이중 이진 터보 부호화는 상당한 부호화 이득을 제공하는 것을 확인할 수 있었다. 또한 터보 복호 과정에서 복호 횟수를 증가시킴에 따라서 시스템 성능이 향상되는 것을 확인할 수 있었다.

Powerline communications (PLC) technology has been discussed and analyzed as a highly potential candidate of wireline access network solutions. In this paper, performance of double binary turbo coded orthogonal frequency division multiplexing (OFDM) system is analyzed and simulated in power line communications channel. In order to make power line channel environments, Bernoulli-Gaussian noise is considered. The performance is evaluated in terms of bit error probability. From the simulation results, it is demonstrated that the double binary turbo coding scheme offers considerable coding gain with reasonable encoding complexity. It is also shown that the system performance can be substantially improved by increasing the number of iterations.

Software maintenance becomes extremely difficult, especially caused by multiple versions in project-based or customer-oriented software development methodology. For reducing the maintenance cost, reengineering to software product line can be a solution to the software which either is a family of products nevertheless little different functionalities or are customized for each different customer's requirement. At an initial stage of the reengineering, the most important activity in software product line is feature extraction with respect to commonality and variability from the existing system due to verifying functional coverage. Several researchers have studied to extract features. They considered only a single version in a single product. However, this is an obstacle to classify the commonality and variability of features. Therefore, we propose a method for systematically extracting features from source code and its change history considering several versions of the existing system. It enables us to represent functionalities reflecting developer's intention, and to clarify the rationale of variation.

An estimation methodology of the mass and energy (M/E) release due to the main steam line break (MSLB) has been developed with the RETRAN-3D code. In the case of equipment qualification (EQ), the over-estimated temperature would exceed the design limits of some cables or valves. In order to have a more flexible EQ profiles from the MSLB M/E release, the methodology with the best-estimated code was used. The major conditions affecting the MSLB M/E were found to be the initial SG level, heat transfer between primary and secondary sides, power level, operable protection system, main or auxiliary feedwater availability, and break conditions. The RETRAN-3D models were developed for the Kori unit 1 (KRN-1) which is typical two loop Westinghouse (WH) designed plant. Particularly, a detailed model of the steam generators was developed to estimate a more realistic two-phase heat transfer effect of the steam flow. After the modeling, the methodology has been developed through the sensitivity analyses. The M/E release data generated from the analyses have been used as the input to the inside containment pressure and temperature (P/T) analysis. According to the results at the point of view containment P/T, the Kori unit 1 can have more margin of 5∼15 ㎪ in pressure and 8∼15$^{\circ}C$ in temperature.

The subchannel analysis was performed to verify the behavior of hot channel characteristics and obtain the information to support the core thermal-hydraulic behavior at post-trip steam line break with low flow condition. During this postulated accident, buoyancy-induced cross flow occurs, and the coupled nuclear and thermal-hydraulic interactions become important. The code predictions with TORC are in good agreement with the test data. Under such conditions, the mass flow increase in the hot channel by buoyancy-induced cross flow depends on the parameter $GR^{*}\;/\;Re^2$, and buoyancy effect becomes more noticeable as $GR^{*}\;/\;Re^2$ increases.

In order to analyze thermal hydraulic phenomena during a DVI (Direct Vessel Injection) line break LOCA (Loss-of-Coolant Accident) in the APR1400 (Advanced Power Reactor 1400 MWe), we performed experimental studies with the SNUF (Seoul National University Facility), a reduced-height and reduce-pressure integral test loop with a scaled down APR1400. We performed experiments dealing with eight test cases under varied tests. As a result of the experiment, the primary system pressure, the coolant temperature, and the occurrence time of the downcomer seal clearing were affected significantly by the thermal power in the core and the SI flow rate. The break area played a dominant role in the vent of the steam. For our analytical investigation, we used the MARS code for simulation of the experiments to validate the calculation capability of the code. The results of the analysis showed good and sufficient agreement with the results of the experiment. However, the analysis revealed a weak capability in predicting the bypass flow of the SI water toward the broken DVI line, and it was insufficient to simulate the streamline contraction in the broken side. We, hence, need to improve the MARS code.

본 논문은 정보통신용 표준 부호인(정보 교환용 부호계 $KS{\times}1001$ : 2004)에 정의되어 있는 한글낱자 부호집합에 대하여, Date link 계층에서 AMI/HDB-3 스크램블링 측면에서 효율적인 데이터 전송을 위한 새로운 부호집합 체계를 제시하였다. 기존 부호집합 체계와 상호비교를 위하여 ($4{\times}4$) 비트 원천부호화 규칙과 한글 빈도통계 (국립국어원)를 적용한 결과 약44 %의 데이터 전송 효율이 개선시킬 수 있음을 나타났다.

This paper, information communication code standard($KS{\times}1001$, confirmation in 2004), as definded in Hangul Character Code Hangul AMI/HDB-3 the code set for the new system Hangul consonant and vowel tables presented. The result of the existing system and the code set ($4{\times}4$) bit source coding rules for comparing the frequency of use Hangul consonant and vowel tables(The National Institute of The Korea Language) and statistices showed that 44% of the data processing efficiency is improved.

본 논문에서는 비전 기반의 1-D 바코드 검출을 위한 스캔 라인 및 범위 결정을 위한 새로운 방법을 제시한다. 블록 HOG(histogram of gradient)를 바탕으로 DBSCAN 군집화 방법을 적용하여 유효한 바코드 대표점 및 방향을 검출하고 이를 바탕으로 스캔 라인 및 바코드 크로스라인을 결정하는 방법에 관한 연구이다. 본 논문에서는 얻어진 스캔라인을 바탕으로 바코드의 크로스라인 범위를 결정하기 위해 최소 및 최대탐색 기법이 적용되었다. 이것은 바코드의 크기에 무관하게 적용될 수 있다. 제안된 기법은 바코드의 일부 영역만 검출해도 바코드 인식이 가능하며, 또한 바코드 영역 검출 후 코드를 읽기 위해 회전을 필요로 하지 않는다. 또한, 다양한 크기의 바코드 검출이 가능하다. 본 논문의 제안된 기법에 대한 성능을 평가를 위해 다양한 실험결과를 제시하였다.

In this paper, we present a new method for determining the scan line and range for vision-based 1-D barcode recognition. This is a study on how to detect valid barcode representative points and directions by applying the DBSCAN clustering method based on block HOG (histogram of gradient) and determine scan lines and barcode crosslines based on this. In this paper, the minimum and maximum search techniques were applied to determine the cross-line range of barcodes based on the obtained scan lines. This can be applied regardless of the barcode size. This technique enables barcode recognition even by detecting only a partial area of the barcode, and does not require rotation to read the code after detecting the barcode area. In addition, it is possible to detect barcodes of various sizes. Various experimental results are presented to evaluate the performance of the proposed technique in this paper.

본 논문에서는 보다 실용적인 온라인 한자인식기 개발을 위하여 한자 검정 능력 1급 쓰기 수준을 모두 포함하는 한자 필기 데이터로부터 16방향의 체인코드열과 부분획의 구조를 반영하는 구조코드열을 만들어 성능평가를 하였다. 인식 방법으로는 DP 매칭 방법과 HMM을 사용하여 2,362 종류의 한자에 대해 인식 실험을 하였다. 그 결과 체인코드열을 사용한 DP 매칭 방법에 의한 결과가 96.54%로 가장 높은 인식률을 보였으며, 구조코드열을 사용하여 HMM에 의한 인식실험 결과가 95.65%로 그 뒤를 이었다. 인식 속도면에서는 체인코드 보다 코드열의 길이가 짧은 구조코드열을 사용한 방법이 상대적으로 유리했고, 클래스 당 1개의 모델을 사용한 HMM에 의한 방법이 클래스 당 복수개의 모델을 사용한 DP 매칭 방법에 비해 모델의 개수가 훨씬 적기 때문에 속도 면에서 월등히 유리해 더 효율적인 인식 성능을 보인다는 결론을 내릴 수 있었다.

전력선은 백색 가우시안 배경 잡음뿐 아니라 임펄스 잡음, 고조파 잡음 등의 비 가우시안 잡음들로 인해 통신 채널로서 열악한 전송 특성을 나타낸다. 또한 좁은 가용 대역폭으로 인해, 광대역 특성이 요구되는 DS-CDMA 방식과 같은 대역 확산 시스템의 적용에 한계가 있다. 본 연구에서는 차세대 고속이동통신을 위한 다원접속/변조방식인 멀티코드 (multi-code) CDMA 방식과 이에 길쌈 부호와 인터리빙 등의 부호화 기능을 더한 시스템을 전력선 통신 시스템에 적용하고, 모의실험을 통해 전력선 채널의 비 가우시안 잡음의 영향을 매우 효과적으로 보상할 수 있음을 확인하였다.

Space-time line code (STLC)라는 새로운 다이버시티 기술의 발명 이후로, 오류율과 에르고딕 용량이 이론적으로 분석되었지만, 아웃티지 확률에 대한 연구가 수행되지 않았다. 본 논문에서는 STLC 시스템의 순시 신호 대 잡음비의 확률 밀도 함수를 도출하고, 아웃티지 확률의 닫힌-형식 표현을 수학적으로 유도하였다. 또한, 전산 실험을 통하여 분석 결과의 정확성을 검증하고, 시스템 설계 및 구현에 대한 통찰을 제시하였다.

Since the invention of a novel diversity technique, namely a space-time line code (STLC), though the previous studies have theoretically analyzed the error rate and ergodic capacity, the outage probability has not been revealed yet. In this paper, we characterize the probability density function of the instantaneous signal-to-noise ratio, and mathematically derive the closed-form expression of the outage probability. Based on numerical simulations, furthermore, we validate the accuracy of the mathematical analysis, and present the insight into the system design and implementation.

최소대역폭 성질을 만족하고, 직류 성분을 지니고, 상태 독립적인 부호화 및 복호화가 가능한 2진 선로부호 MB46d BUDA 셀 기법을 응용하여 설계하였다. 설계된 선로부호 MB46d는 하나의 상태만 존재하므로 앞 상태에 무관하게 부호화할 수 있으며 데이터 메모리 용량이나 하드웨어가 간단하다. 또한, 최대 연속장이 8로 제한되어 있으므로, 수신 측에서 시각 정보를 많이 가져 자체 동기 기능을 가지며, 복호화 규칙이 매우 간단하며, 임펄스 응답 함수가 Raised cosine pulse인 시스템에서 최악의 경우에도 눈 모양이 크게 열려있으므로 어느 정도의 샘플링 지터가 존재하더라도 오류 없는 수신이 가능하다. 제안된 2진 선로부호 MB46d는 직류 성분성질을 제한하지 않은 반면에 고주파 성분을 더욱 억압하여 캐리어 파일럿 삽입 시 데이터 스펙트럼과 파일럿 사이의 간섭을 최소화 할 수 있다는 장점도 가지고 있다.

A binary line code, called MB46d, is designed by use of the BUDA(Binary Unit DSV and ASV) cell concept to retain the property of being runlength limited, DC tree, and with a power spectral null at the Nyquist frequency. This new code is a stateless line code with a simple encoding and a decoding rule and enables efficient error monitoring. The power spectrum and the eye pattern of the new line code are simulated for a minimum-bandwidth digital transmission system where the sinc function is used as a basic pulse. The obtained power null at the Nyquist frequency is wide enough to enable easy band-limiting as well as secure insertion of a clock pilot where necessary. The eye is also substantially wide to tolerate a fair amount of timing jitter in the receiver.