• 한국음향학회지
• /
• 제21권2호
• /
• pp.120-127
• /
• 2002

본 논문에서는 일반적인 코드분할 다중화 시스템을 위해 저자가 제안하였던 유사 역상관기 (pseudo-decorrelator)를 변형하여 광대역 코드분할 다중화 시스템에 적합한 다중사용자 수신기를 설계하고, 레일레이 다중 경로 채널 환경에서 성능을 분석하고 있다. 설계된 수신기에서는 판단변수 (decision statistics)에 포함되어 있는 다중사용자 간섭신호를 분석하여, 송신된 신호의 각 비트에 대응되는 상호상관 행렬을 얻게 된다. 이 상호상관 행렬에 대한 일반 역행렬을 구한 후 기존의 수신기에서 얻어진 판단변수에 적용함으로써, 수신기의 성능을 향상시킬 수 있다. 제안된 수신기는 원근저항성을 가질뿐 만 아니라, 동기검출 회로가 완전하지 않아서 시간지연 오차나 위상 오차가 생기는 경우에도 기존의 수신기에 비해 좋은 성능을 보여준다.

• 한국위성정보통신학회논문지
• /
• 제12권1호
• /
• pp.38-42
• /
• 2017

본 논문은 양자 키 분배 시스템에서의 보안성을 증폭시키기 위한 이중 해시 함수의 개념을 소개한다. 양자 오류 정정과 보안사이의 관계를 이용하여 보안성 증폭을 제공하는 것을 보인다. 또한 보안성 증폭 측면에서 접근 방식이 위상 오차 보정 방식이 더 보다 나은 보안성을 제시한다는 것을 보인다. QKD의 대표적인 예인 BB84 프로토콜을 이용하여 유니버셜 해시 함수가 보안성을 강화하는 과정을 설명한다. 마지막으로 결정적인 유니버셜 해시 함수가 메시지의 길이에 의존하지 않고 양자 Pauli 채널에서 보안성을 평가 받는 것을 유도한다.

• 제어로봇시스템학회논문지
• /
• 제18권11호
• /
• pp.997-1004
• /
• 2012

In enterprise software projects, performance issues have become more critical during recent decades. While developing software products, many performance tests are executed in the earlier development phase against the newly added code pieces to detect possible performance regressions. In our previous research, we introduced the framework to enable automated performance anomaly detection and reduce the analysis overhead for identifying the root causes, and showed Statistical Process Control (SPC) can be successfully applied to anomaly detection. In this paper, we explain the special performance trend in which the existing anomaly detection system can hardly detect the noticeable performance change especially when a performance regression is introduced and recovered again a while later. Within the fixed number of sampling period, the fluctuation gets aggravated and the lower and upper control limit get relaxed so that sometimes the existing system hardly detect the noticeable performance change. To resolve the issue, we apply dynamically tuned sampling window size based on the performance trend, and Fuzzy theory to find an appropriate size of the moving window.

• 한국분무공학회지
• /
• 제12권1호
• /
• pp.18-29
• /
• 2007

Feedwater heaters of many nuclear power plants have recently experienced severe wall thinning damage, which will increase as operating time progresses. Several nuclear power plants in Korea have experienced wall thinning damage in the area around the impingement baffle - installed downstream of the high pressure turbine extraction steam line - inside number 5A and 5B feedwater heaters. At that point, the extracted steam from the high pressure turbine is two phase fluid at high temperature, high pressure, and high speed. Since it flows in reverse direction after impinging the impingement baffle, the shell wall of the number 5 high pressure feedwater heater may be affected by flow-accelerated corrosion. This paper describes the comparisons between the numerical analysis results using the FLUENT code and the down scale experimental data in an effort to determine root causes of the shell wall thinning of the high pressure feedwater heaters. The numerical analysis and experimental data were also confirmed by actual wall thickness measured by an ultrasonic test.

• Acta Via Serica
• /
• 제1권1호
• /
• pp.119-135
• /
• 2016

The initial phase of the Mongol invasion resulted in the establishment of relative political stability in the vast expanses of Eurasia, which came under the control of a single political entity - the Mongol realm. This contributed to a fairly rapid restoration of the commercial links and trade routes between the East and the West. During this period, Chinese silk again became available in large quantities in the Western markets. At the same time, the beginning of silk production and manufacturing of silk fabrics in Italy and the fashion flash for these goods in Western countries affected trade between Europe and the Muslim world. The centers of silk production in the Ilkhanid Empire were some provinces of Azerbaijan and Persia, where from it was exported in large numbers along the trade routes of Anatolia and Syria to the Mediterranean ports and further to the west. There are numerous testimonies of European travelers, and Muslim authors related the international silk trade in 13th-15th centuries, ie in the era from the Mongol Ilkhanid Empire till the reign of the Turkman Aqqoyunlu dynasty. One of the most informative documentary sources on this issue are the legislative codes (kanuname) of sultan Uzun Hasan from the Aqqoyunlu dynasty regarding the eastern provinces of the Asia Minor. This article presents and analyzes the information from these documents concerning the whole range of goods related to silk and silk fabrics trade in the period under the consideration.

• 설비공학논문집
• /
• 제19권6호
• /
• pp.434-440
• /
• 2007

One of the cold start problems of a FCV is the freezing of the water in the water tank when a FCV is not in operation and the surrounding temperature drops below $0^{\circ}C$. The ice in the tank should be melted as quickly as possible for a satisfactory operation of fuel cell vehicles. In this study, the melting process for the constant heat fluxes of the plate heaters was numerically calculated in the 2-D model of the tank and plate heaters. The enthalpy method and FVM code was used for this analysis. The changes of the temperature with heat fluxes and the heat transfer area could be investigated. The energy balance error was found to increase with the heat flux. From this numerical analysis, the proper heat flux value and some important design factors relating local overheating and pressurization of the water tank could be examined.

• 대한기계학회논문집B
• /
• 제23권2호
• /
• pp.254-261
• /
• 1999

An optimal design code for centrifugal pumps has been developed to determine geometric and fluid dynamic variables under appropriate design constraints. The optimization problem has been formulated with a nonlinear objective function to minimize one, two or all of the fluid dynamic losses, the net positive suction head required and the product price of a pump stage depending on the weighting factors selected as the design compromise. The optimal solution Is obtained by means of the Hooke and Jeeves direct search method. The performance analysis Is based on the mean streamline analysis using the present state-of-the-art loss correlations. The optimized efficiency and design variables of centrifugal pumps are presented in this paper as a function of non-dimensional specific speed in the range, $0.5{\leq}N$, ${\leq}1.3$. The diagrams presented herein can be used efficiently in the preliminary design phase of centrifugal pumps.

• 한국전자통신학회논문지
• /
• 제11권1호
• /
• pp.93-98
• /
• 2016

사건 및 사고로 다수의 피해자 또는 참고인들은 경찰서를 방문하고 진술 조서를 작성한다. 진술 조서 과정 중오기 또는 오타로 인하여 수정이 요청 되었을 때 수정 부분을 수정한 후 지문을 이용하여 수정되었음을 인정하는 불필요한 단계 과정에서 불편함과 위생적 문제점을 해결하고, 경찰의 내 수사 단계에서 진술조서 작성 시 KICS와 전자 수사자료표 시스템을 연동한 지문인식기 도입으로 원터치 신원 확인 및 간인 날인 절차를 간소화 할 수 있다.

• Journal of Radiation Protection and Research
• /
• 제29권1호
• /
• pp.33-39
• /
• 2004

In order to vitrify the W1 waste (ion-exchange resin(IER), zeolite, and dry active waste(DAW)) generated from Korean Nuclear Power Plants, a glass formulation development based on waste compositions and production rates was performed. A aluminoborosilicate glass, AG8W1, was formulated to vitrify the W1 waste in an induction cold crucible melter(CCM). The processability, product performance, and economics of the candidate glass were calculated using a computer code and were measured experimentally in the laboratory and CCM. The glass viscosity and electrical conductivity as the process parameters were in the desired ranges. Start-up and maintaining glass melt of the candidate glass were favorable in the CCM. The product quality of the glass such as chemical durability, phase stability, etc. was satisfactory. The vitrification process using the candidate glass was also evaluated to be operated as economically as possible.

• 한국인터넷방송통신학회논문지
• /
• 제8권4호
• /
• pp.119-125
• /
• 2008

스마트 기기의 컨버전스를 위한 기존의 방법은 미들웨어를 사용하여 소프트웨어를 통합하는 것이다. 미들웨어를 사용하면 쉽고 빠르게 통합이 가능한 장점이 있다. 하지만 미들웨어는 기본적으로 소프트웨어가 크기 때문에 수행 속도가 느리다. 이러한 단점을 극복하기 위해 본 논문에서는 컨버전스를 위한 모델링 도구를 제안한다. 제안하는 모델링 도구는 모델 단계에서 컨버전스를 수행하고 자동코드를 생성하여 미들웨어 없이 소프트웨어의 컨버전스가 가능 하게 한다. 적용사례로서 u-Home 환경의 텔레비전과 도어락 시스템의 컨버전스를 보여주었다. 미들웨어를 사용하지 않아 저렴한 비용으로 스마트 기기의 컨버전스를 수행하였고 사용자가 원하는 컨버전스 제품을 빠르게 개발할 수 있었다.