• 소성∙가공
• /
• 제32권5호
• /
• pp.239-246
• /
• 2023

To reduce the forming load due to the temperature drop, during the hot forging process, a reheating hot forging process design is required that to repeat heating and forging. However, if the critical strain required for recrystallization is not induced during forging and grain growth becomes dominant due to the reduction in dislocation density due to repeated heating, the mechanical properties may deteriorate. Therefore, in this study, Inconel 706 alloy was applied, and the grain refinement behavior was comparatively analyzed according to the number of reheating times and effective strain during reheating hot forging process. Reheating was carried out with a total compression rate of 40% up to 4 times. The Inconel 706 compression test specimens heated once showed finer grains as the effective strain increased due to the dynamic recrystallization phenomenon. However, as the number of heating increases, grain refinement was observed even in a low effective strain distribution of 0.43 due to static recrystallization during reheating. Moreover, grain growth occurs at a relatively low effective strain of 0.43 when the number of reheating is four or more. Therefore, it was effective to apply an effective strain of 0.43 or more during hot forging to Inconel 706 in order to induce crystallization through grain refinement and improve the properties of forged products. In addition, we could notice that up to three reheating times condition was appropriate to prevent grain growth and maintain fine grain size.

• 정보통신설비학회논문지
• /
• 제11권2호
• /
• pp.29-33
• /
• 2012

ECG widely used in cardiac function test is a graph that is recorded by measuring the electrical impulses occurred in the heart. Normal ECG has the form of similar sections that are repeated, and each section has the information occurred in a heart beat. Thus, In order to make the correct diagnosis, correct grasp of the sections and formed analysis must be done. In this research, a system that detects the sections of ECG is proposed. The system is based on ECG stored in the form of files. The ECG can easily have a noise caused by an outside factor. The noise of ECG is easily caused by external factors. Through a band-pass filter, it can be removed. and then, to get this ECG without a noise, interval detection algorithm using R-peak is applied. The clean, intuitive interface will help the above functions to be used without any difficulties.

• 소성∙가공
• /
• 제21권7호
• /
• pp.432-440
• /
• 2012

In this article, the design of the flexible forming process considering die shape compensation using an iterative over-bending method based on numerical simulation was conducted. In this method, the springback shape obtained from the final step of the first forming simulation is compared with the desired objective shape, and a shape error is calculated as a vector norm with three-dimensional coordinates. The error vector is inversely added to the objective surface to compensate both the upper and lower flexible die configurations. The flexible die shapes are recalculated and the punch arrays are adjusted according to the over-bent forming surface. These iterative procedures are repeated until the shape error variation converges to a small value. In addition, experimental verification was conducted using a 2000-kN flexible forming apparatus for thick plates. Finally, the configuration of the prototype obtained from the experiment was compared with the numerical simulation results, which had springback compensation. It is confirmed that the proposed method for compensating for the forming error could be used in the design of flexible forming of thick-curved plates.

• 한국산업정보학회논문지
• /
• 제22권3호
• /
• pp.27-38
• /
• 2017

본 연구는 다수의 개인 사용자들이 휴대폰 카메라를 통하여 공연장 등에서 녹화한 다수의 영상을 스티칭하는 방법을 제시한다. 기존 고정형 리그(Rig)를 사용하는 360 카메라 솔루션과 대비하여, 시간 동기화, 반복적 변환행렬계산 및 카메라 센서 불일치 보정과 같은 새로운 문제들을 해결해야한다. 이 논문에서는 오디오를 사용한 시각동기화 방법, 색상 전달 방식에 따른 센서 불일치 제거, 전역 동작 안정화 알고리즘을 사용하여 변환 행렬의 업데이트를 함으로써 이러한 문제를 해결하였다. 또한, 카메라의 움직임이 크지 않은 경우에서, 제안 된 알고리즘은 화면 별 스티칭을 하는 경우 보다, 계산 속도와 화질 면에서도 우수한 성능을 보임을 실험을 통하여 확인하였다.

• 한국IT서비스학회지
• /
• 제17권3호
• /
• pp.63-75
• /
• 2018

In this paper, we propose a testing method of the quality of device application effectively reflecting the necessity of increasing mobile device application quality test, and designed and developed it as a web system. We have studied traditional software testing methods for designing and developing a system. We have developed a next-generation alternative technology that can analyze and compensate for the weaknesses of the web and weaknesses of the Android in order to realize the access system and the responsive web system. As an example applied to the system, we analyzed the requirements of the system implementation and expressed the functions of the system through the use case diagram. The test scenarios were conducted by connecting 5,000 devices to each system using the existing HTTP polling method and the proposed web socket method. After setting the comparative group, the result of the proposed web management system was observed and compared through repeated tests. The research shows that the proposed web socket system has better performance than HTTP polling. The more the number of simultaneous processing of the devices, the lower the server stability but the better the time efficiency. In conclusion, the more the number of devices to be tested is, the more the number of devices can be effectively tested using the proposed web management system.

• 한국소음진동공학회논문집
• /
• 제22권1호
• /
• pp.61-73
• /
• 2012

The paper presents the novel approach to solve some problems occurred in application of the genetic algorithm to the determination of the optimal tire pattern sequence in order to reduce the tire air-pumping noise which is generated by the repeated compression and expansion of the air cavity between tire pattern and road surface. The genetic algorithm has been used to find the optimal tire pattern sequence having a low level of tire air-pumping noise using the image based air-pumping model. In the genetic algorithm used in the previous researches, there are some problems in the encoding structure and the selection of objective function. The paper proposed single encoding element with five integers, divergent objective function based on evolutionary process and the optimal evolutionary rate based on Shannon entropy to solve the problems. The results of the proposed genetic algorithm with evolutionary process are compared with those of the randomized algorithm without evolutionary process on the two-dimensional normal distribution. It is confirmed that the genetic algorithm is more effective to reduce the peak value of the predicted tire air-pumping noise and the consistency and cohesion of the obtained simulation results are also improved in terms of probability.

• Journal of Plant Biotechnology
• /
• 제31권4호
• /
• pp.261-266
• /
• 2004

Agrobacterium을 이용하여 도입된 유전자의 세대진전, 교잡 등에 따른 유전적 안정성을 확인코자, 형질 전환으로부터 얻어진 bar 유전자가 도입된 형질전환 식물체들을 상호 교배, 여교배, T$_4$ 세대까지의 자식의 반복 등에 의해 유전적 안정성을 검토하였다. 조합이나 계통에 따라서는 일부 멘델식 분리를 따르지 않고 제초제 Basta에 대한 저항성이 사라지거나 저항성개체보다 감수성개체가 기대치보다 많은 등의 경우가 있었으나, 대부분 멘델식 분리를 따르고 있어 세대진전, 교배 등에 의해서도 유전적 안정성이 높게 유지됨을 확인할 수 있었다.

• 한국재료학회지
• /
• 제5권4호
• /
• pp.397-404
• /
• 1995

반도체 세정공정에서 염기성 세정액(SCI, Standard cleaning 1, $NH_{4}$OH + $H_{2}$O_{2}$ + $H_{2}$O)은 공정상 발생되는 여러 오염물 중 파티클의 제거를 위해 널리 사용되고 있는데, SCI 조성중 $NH_{4}$OH양에 따라 세정 중 실리콘의 식각속도를 증가시킨다. 이 연구에서는 SCI 세정이 CZ(Czochralski)와 에피 실리콘 기판 표면에 미치는 영향을 단순세정과 연속적인 산화-HF 식각-SCI 세정공정을 통해 관찰되었다. CZ와 에피 기판을 8$0^{\circ}C$의 1 : 2 : 10과 1 : 1 : 5 SCI 용액에서 60분까지 단순 세정을 했을 때 laser particle scanner와 KLA사의 웨이퍼 검색장치로 측정된 결함의 수는 세정시간에 따라 변화를 보이지 않았다. 그러나 CZ와 에피 기판을 10분간 SCI 세정후 90$0^{\circ}C$에서 산화 HF식각공정을 4번까지 반복하였을 때 에피 기판 표면의 결함수는 감소하는 반면에 CZ기판에서는 직선적으로 증가하였다. 반복적인 산화-HF 식각-XCI 세정공정을 통해 생성된 CZ기판 표면의 결함은 크기가 0.7$\mu$m 이하의 pit과 같은 형상을 보여주었다. 이들 결함은 열처리 중 CZ 기판내와 표면에 산화 석출물들이 형성, 반복적인 HF 식각-SCI 세정공정을 통해 다른 부위에 비해 식각이 빨리 일어나 표면에 생성되는 것으로 여기어 진다.

• 정보처리학회논문지C
• /
• 제18C권1호
• /
• pp.1-6
• /
• 2011

암호학의 암호 생성과 해독, 소수판별법의 성능은 대부분 $a^b$(mod n)의 모듈러 지수연산의 효율적 구현여부로 결정된다. 모듈러 지수연산법에는 표준 이진법이 최선의 선택으로 알려져 있다. 그러나 큰 자리수의 b에 대해서는 d-ary, (d=2,3,4,5,6)이 보다 효율적으로 적용된다. 본 논문에서는 $b{\equiv}0$(mod m), $2{\leq}m{\leq}16$인 경우 b를 m-진법으로 변환시켜 수행하는 방법과 m-진법 수행과정에서 결과 값이 1 또는 a가 발생하는 경우 곱셈 수행횟수를 획기적으로 줄이는 방법을 제안하였다.

• 대한산업공학회지
• /
• 제30권2호
• /
• pp.107-119
• /
• 2004

A study on the following parallel machine problem is addressed in this research. An order is completed only when a given number of processes (cycle) are repeated. Anew cycle is possible only upon the completion of the previous cycle. Orders are classified into job group according to product feature. For a machine to switch to a different job group from the currently processing one a major setup is required while a minor setup time is inserted in between two jobs of the same job group. The objective of the study is to find a schedule that minimizes total weighted tardiness. An initial solution is obtained by the RATCS(Restricted Apparent Tardiness Cost with Setup) rule, and a Tabu search is applied to improve the solution. Numerical examples are also presented.