• Journal of Information Processing Systems
• /
• v.7 no.3
• /
• pp.435-446
• /
• 2011

Microprocessors are becoming increasingly vulnerable to soft errors due to the current trends of semiconductor technology scaling. Traditional redundant multi-threading architectures provide perfect fault tolerance by re-executing all the computations. However, such a full re-execution technique significantly increases the verification workload on the processor resources, resulting in severe performance degradation. This paper presents a pro-active verification management approach to mitigate the verification workload to increase its performance with a minimal effect on overall reliability. An anomaly-speculation-based filter checker is proposed to guide a verification priority before the re-execution process starts. This technique is accomplished by exploiting a value similarity property, which is defined by a frequent occurrence of partially identical values. Based on the biased distribution of similarity distance measure, this paper investigates further application to exploit similar values for soft error tolerance with anomaly speculation. Extensive measurements prove that the majority of instructions produce values, which are different from the previous result value, only in a few bits. Experimental results show that the proposed scheme accelerates the processor to be 180% faster than traditional fully-fault-tolerant processor with a minimal impact on overall soft error rate.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 1998.11a
• /
• pp.165-168
• /
• 1998

Re-oxidized nitrided oxides which have been investigated as alternative gate oxide for Metal- Oxide -Semiconductor field effect devices were grown by conventional furnace process using pure NH$_3$ and dry $O_2$ gas, and were characterized via a Fowler-Nordheim Tunneling electron injection technique. We studied Ig-Vg characteristics, leakage current, $\Delta$Vg under constant current stress from electrical characteristics point of view and TDDB from reliability point of view of MOS capacitors with SiO$_2$, NO, ONO dielectrics. Also, we studied the effect of stress temperature (25, 50, 75, 100, and 1$25^{\circ}C$). Overall, our results indicate that optimized re-oxidized nitrided oxide shows improved Ig-Vg characteristics, leakage current over the nitrided oxide and SiO$_2$. It has also been shown that re-oxidized nitrided oxide have better TDDB performance than SiO$_2$ while maintaining a similar temperature and electric field dependence. Especially, the Qbd is increased by about 1.5 times.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2016.05a
• /
• pp.782-784
• /
• 2016

In this study, we studied the gamma-radiation effect of fiber Bragg gratings on the fiber re-coating methods. The fiber Bragg gratings were exposed to gamma-radiation up to a dose of 100 kGy at the dose rate of 104 Gy/min. In our experimental results, we confirmed that the fiber acrylate re-coating process leads to a slightly lower radiation sensitivity of FBGs.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.35 no.3
• /
• pp.163-172
• /
• 2012

Regarding project management, many organizations have developed and distributed general project management knowledge systems, and application fields use the knowledge systems to apply the process suitable for characteristics of a project. This study suggests project management process models to apply to system integration projects. This system integration project management process model is composed of six top processes of initiation, preparation for contract, planning, implementation management, coordination and control, and termination and transfer. The five processes are re-divided into 25 bottom processes. These processes are expressed as input, control, output, and mechanism by using the IDEF0 model. For this model development, it has chosen the items which constituted a process through a questionnaire of experts.

• Korean Journal of Materials Research
• /
• v.23 no.1
• /
• pp.24-30
• /
• 2013

Today, the modification of carbon foam for high performance remains a major issue in the environment and energy industries. One promising way to solve this problem is the optimization of the pore structure for desired properties as well as for efficient performance. In this study, using a sol-gel process followed by carbonization in an inert atmosphere, hollow spherical carbon foam was prepared using resorcinol and formaldehyde precursors catalyzed by 4-aminobenzoic acid; the effect of carbonization temperature and re-immersion treatment on the pore structure and characteristics of the hollow spherical carbon foam was investigated. As the carbonization temperature increased, the porosity and average pore diameter were found to decrease but the compression strength and electrical conductivity dramatically increased in the temperature range of this study ($700^{\circ}C$ to $850^{\circ}C$). The significant differences of X-ray diffraction patterns obtained from the carbon foams carbonized under different temperatures implied that the degree of crystallinity greatly affects the characteristics of the carbon form. Also, the number of re-impregnations of carbon form in the resorcinol-formaldehyde resin was varied from 1 to 10 times, followed by re-carbonization at $800^{\circ}C$ for 2 hours under argon gas flow. As the number of re-immersion treatments increased, the porosity decreased while the compression strength improved by about four times when re-impregnation was repeated 10 times. These results imply the possibility of customizing the characteristics of carbon foam by controlling the carbonization and re-immersion conditions.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.31 no.4
• /
• pp.106-113
• /
• 2008

본 논문에서는 유한용량 재진입 생산라인에서의 스케줄링 문제에 대한 유전자적 접근 방법을 제안하였다. 알고리즘에서 사용되는 염색체의 구조는 워크스테이션의 버퍼레벨에 대한 모든 가능한 경우를 고려하여 정의되었으며, 염색체의 각 유전자에는 그에 대응되는 시스템 상태에서 우선 순위를 갖는 작업 단계의 값이 할당되도록 하였다. 또한, 제안된 알고리즘의 구현 방법으로서 워크스테이션의 버퍼와 프로세싱 자원을 할당할 때 작업 간 우선 순위를 고려하는 동시에 각 워크스테이션의 로컬 유휴 상태를 지양하는 우선순위 기반 랜덤화 정책 알고리즘을 제안하였다. 실험을 통하여 제안된 알고리즘의 성능을 평가하였으며, 기존에 무한용량 재진입 생산라인 스케줄링 문제에 많이 이용되었던 휴리스틱과 비교하여 보다 효율적임을 보였다.

• Proceedings of the Korean Magnestics Society Conference
• /
• 2013.12a
• /
• pp.89-89
• /
• 2013

Rare earth (RE) - transition metal based high energy density magnets are of immense significance in various engineering applications. $Nd_2Fe_{14}B$ magnets possess the highest energy product and are widely used in whole industries. Simultaneously, composite alloys that are cheap, cost effective and strong commercially available have drawn great attention, because rare-earth metals are costly, less abundant and strategic shortage. We designed rare-earth free alloys and fabrication process and developed novel route to prepare $Nd_2Fe_{14}B$ powders by wet process employing spray drying and reduction-diffusion (R-D) without the use of high purity metals as raw material. MnAl-base permanent magnetic powders are potentially important material for rare-earth free magnets. We have prepared the nano-sized MnAl powders by plasma arc discharge and micron-sized MnAl powders by gas atomization. They showed good magnetic property, compared with that from conventional processes. $Nd_2Fe_{14}B$ powders with high coercivity of more than 10 kOe were successfully synthesized by adjusting R-D step, followed by precise washing system. It is considered that this process can be applied for the recycling of RE-elements extracted from ewaste including motors.

• Journal of the Korean Chemical Society
• /
• v.64 no.2
• /
• pp.84-98
• /
• 2020

In this study, we analyzed the influences of lecture design using CoRe upon the professor's teaching professionalism in the aspects of pedagogical content knowledge (PCK). The participants are three professors from the college of science-engineering located in Chungcheong-do. After collecting their syllabi, we observed their lecture and conducted the orientation. Afterward, we collected the CoRes which they prepared before the lecture. Then we observed their lecture and conducted semi-structured interviews. This process was carried out twice. We analyzed their syllabi, CoRes, videotaped lectures, field notes, the teaching materials, and interview transcripts. The results revealed that professors not only clarified the learning objectives and the characteristics of students but also reflected them in the lecture. In addition, they established the teaching strategies according to the characteristics of contents in the unit. As they recognized the necessity of understanding students' achievement, they selected the assessment method and applied it in the lecture. In some cases, however, they lacked presenting learning objectives specifically and explained students' misconceptions without inducing new concepts. They also presented a shortage of considering students' prior knowledge. They lacked providing students with an opportunity to participate in lectures, and their assessment method was not effective. Based on the results, we discussed implications to improve teaching professionalism using CoRe.

• Journal of Powder Materials
• /
• v.15 no.5
• /
• pp.371-377
• /
• 2008

This paper deals with the phase analysis of $MgB_2$ bulk using spark plasma sintering process after ball milling. Mg and amorphous B powders were used as raw materials, and milled by planetary-mill for 9 hours at argon atmosphere. In order to confirm formation of $MgB_2$ phase, DTA and XRD were used. The milled powders were fabricated to $MgB_2$ bulk at the various temperatures by Spark Plasma Sintering. The fabricated $MgB_2$ bulk was evaluated with XRD, EDS, FE-SEM and PPMS. In the DTA result, reaction on formation of $MgB_2$ phase started at $340^{\circ}C$. This means that ball milling process improves reactivity on formation of $MgB_2$ phase. The $MgB_2$ MgO and FeB phases were characterized from XRD result. MgO and FeB were undesirable phases which affect formation of $MgB_2$ phase, and it's distribution could be confirmed from EDS mapping result. Spark Plasma Sintered sample for 5 min at $700^{\circ}C$ was relatively densified and it's density and transition temperature showing super conducting property were $1.87\;g/cm^3$ and 21K.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.14 no.2
• /
• pp.14-18
• /
• 2015

In recent years, world is faced with a transportation energy dilemma, and the transportation is almost dependent on a single fuel - petroleum. However, Hybrid Electric Vehicle (HEV) technology holds more advantages to reduce the demand for petroleum in the transportation by efficiency improvements of petroleum consumption. Therefore, there is a trend that lower gear noise levels are demanded in HEV for drivers to avoid annoyance and fatigue during operation. And meshing transmission error (T.E.) is the excitation that leads to the tonal noise known as gear whine, and radiated gear whine is also the dominant source of noise in the whole gearbox. In this paper, the analysis of gear tooth profile and lead modification is firstly presented, and then, the different transmission error of no mesh misalignment and mesh misalignment under one loaded torque for the 1st gear pair of HEV gearbox was investigated and compared. At last, the appropriate tooth modification was used to minimize and compare the transmission error of the gear pair with mesh misalignment under the loaded torque.