• Journal of the Institute of Convergence Signal Processing
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• v.16 no.4
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• pp.139-148
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• 2015

In this paper, the optimum coding method is proposed by using open library in order to improve the performance of a software correlator developed for Korea-Japan Joint VLBI Correlator(KJJVC). The correlation system for VLBI observing system is generally implemented with hardware using ASIC or FPGA because the computational quantity is increased geometrically according to the participated observatory number. However, the software correlation system is recently constructed at a massive server such as a cluster using software according to the development of computing power. Since VLBI correlator implemented with hardware is able to conduct data processing with real-time or quasi real-time compared with mostly observational time, software correlation has to perform optimal data processing in coding work so as to have the same performance as that of the hardware. Therefore, in this paper, the experimental comparison was conducted by open-source based fftw library released in FFT processing stage, which is the most important part of the correlator system for performing optimum coding work in software development phase, such as general method using fftw library or methods using SSE(Streaming SIMD Extensions), shared memory, or OpenMP, and method using merged techniques listed above. Through the experimental results, the proposed optimum coding method for improving the performance of developed software correlator using fftw library, shared memory and OpenMP is effectively confirmed by reducing correlation time compared with conventional method.

• Journal of The Korean Association For Science Education
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• v.32 no.4
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• pp.775-788
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• 2012

This study was done at a scientific camp sponsored by Nara Women's University Secondary School, Japan. In this school, $10^{th}$ grade students from 4 East Asian countries: Korea, Japan, Taiwan, and Singapore, participated. We made a research on students' perceptions about nuclear energy. Sample populations include 77 students in total, with 12 Korean, 46 Japanese, 9 Taiwanese and 10 Singaporean students. Overall perceptions comparison about nuclear energy shows average values from the order of highest Korea, Taiwan, Singapore, and to lowest, Japan. We implemented a T-test to identify perception differences about nuclear energy, with one group that include 3 countries (Korea, Taiwan and Singapore) and another group that includes all the Japanese students. T-test results of perceptions about nuclear energy shows students from the 3 countries of Korea, Taiwan and Singapore having higher average than Japanese students. (p<.05). Korean average scores regarding overall perceptions about nuclear energy show as the highest in all 4 East Asian countries and also highest in all subcategories. On the contrary in Japan, they have lower and negative perceptions of nuclear energy. In spite of these facts, perceptions of Japanese students about nuclear energy seem lowest and negative mainly because of the recent Fukushima nuclear power plant disaster, caused by the tsunami and its subsequent damages and fears of radiation leaks, etc. This shows that negative information about future disasters and its resulting damages like the Chernobyl nuclear accident could influence more on people's risk perception than general information like nuclear energy-related technologies or the news that the plant is operating normally, etc. Even if the possibility of this kind of accident is very low, just one accident could bring abnormal risks to technology itself. This strong signal makes negative image and strengthens its perceptions to the people. This could bring a stigma about nuclear energy. This study shows that Government's policy about the highest priority for nuclear energy safety is most important. As long as such perception and decision are fixed, we found that it might not be easy to get changed again because they were already fortified and maintained.

• Journal of Digital Convergence
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• v.10 no.8
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• pp.119-133
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• 2012

Recent rise of social media channel is changing social and economic paradigm and is being used as an effective communication in marketing. The following research analyzes the most employed social marketing tools such as portal advertisement, blogs, and SNS channels to effectively execute social media marketing from performance indicator and ICSI perspective, analyzes each channel's characteristics and results based on Korea distribution companies' case studies and suggests a framework to effectively use each channel. Portal site advertisements are the most effective channel to draw customers with new information and are thus linked to profit by corporations with excessive budget and workforce. Blogs target a specific range of customers providing quality information and knowledge thus improving a corporation's and its product's trustworthiness, spread the word by allowing customers to scrap the information, form social groups and synthesize ideas, events, new contents and social involvement with loyal customers. SNS channels allow customers to get involved in real time information and events, grow through network by the power of customers, react immediately to customers' needs, and execute real-time market and customer reports. Though national corporations currently rely heavily on portal site advertisements, insightful marketing professionals are showing financial results with blog and SNS. In the future, based on a precise understanding of each channel's benefits and expected results, and with a focus on flexibility, timeliness and integrated use of each channel, a portfolio of dynamic marketing as a maximizing strategy could be synthesized.

• Progress in Medical Physics
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• v.13 no.3
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• pp.129-134
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• 2002

The radiosurgery is planned that prescribed dose was irradiated to tumor for obtaining expected remedial value in stereotactic radiosurgery. The planning for many irregular tumor shape requires long computation time and skilled planners. Due to the rapid development in computer power recently, many optimization methods using computer has been proposed, although the practical method is still trial and error type of plan. In this study, many beam variables were considered and many tumor shapes were assumed cylinderical ideal models. Then, beam variables that covered the target within 50％ isodose curve were searched, the result was compared and analysed. The beam variables considered were isocenter separation distance, number of isocenters and collimator size. Dose distributions obtained with these variables were analysed by dose volume histogram(DVH) and dose profile at orthogonal plane. According to the results compared, the use of more isocenters than specified isocenter dosen't improve DVH and dose profile but only increases complexity of plan. The best result of DVH and dose profile are obtainedwhen isocenter separation was 1.0-1.2 in using same number of isocenter.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.14 no.1
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• pp.22-28
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• 2021

Multivariate processes, such as chemical and mechanical process, power plants are operated in a state where several facilities are complexly connected, the fault of a particular system can also have fatal consequences for the entire process. In addition, since process data is measured in an unstable environment, outlier is likely to be include in the data. Therefore, monitoring technology is essential, which can remove outlier from measured data and detect failures in advance. In this paper, data obtained from dynamic and multivariate process models was used to detect fault in various type of processes. The dynamic process is a simulation of a process with autoregressive property, and the multivariate process is a model that describes a situation when a specific sensor fault. Mahalanobis distance was used to remove outlier contained in the data generated by dynamic process model and multivariate process model, and fault detection was performed using ICA. For comparison, we compared performance with and a conventional single ICA method. The proposed fault detection method improves performance by 0.84%p for bias data and 6.82%p for drift data in the dynamic process. In the case of the multivariate process, the performance was improves by 3.78%p, therefore, the proposed method showed better fault detection performance.

• The Journal of Engineering Geology
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• v.23 no.2
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• pp.105-115
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• 2013

Increasing the river cross-section by barrage construction causes rises in the average river water levels and discharge rates in the rainy season. The time series patterns for groundwater levels measured at 23 riverside monitoring wells along the lower Nakdong River are compared for two cases: before and after water-filling at the Changnyeong-Haman Barrage. Monthly average groundwater levels indicate a distinct increase in groundwater levels in the upstream riverside close to the barrage. River-water level management by barrage gate control in August, during the rainy season, resulted in a 0.1 m decrease in groundwater levels, while water-filling at the barrage in December caused a 1.3 m increase in groundwater levels. The results of hierarchical cluster analysis indicate that seven groundwater monitoring wells and river water levels were in the same group before barrage construction, but that this number increased to 14 after barrage construction. Principal component analysis revealed that the explanation power of two principal components corresponding to river fluctuation, PC1 and PC2, was approximately 82% before barrage construction but decreased to 45% after construction. This finding indicates that the effect of the river level component that contributes to change in groundwater level, decreases after barrage construction; consequently, other factors, including groundwater pumping, become more important. Continuous surveying and monitoring is essential for understanding change in the hydrological environment. Water policy that takes groundwater-surface water interaction into consideration should be established for riverside areas.

• Journal of Internet Computing and Services
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• v.16 no.3
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• pp.1-11
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• 2015

WBAN(Wireless Body Area Network) operating around the human body aims at medical and non-medical service at the same time. and it is the short-range communication technology requiring low-power, various data rate and high reliability. Various studies is performing for IEEE 802.15.4, because IEEE 802.15.4 can provide high compatibility for operate WBAN among communication standard satisfiable these requirements. Meanwhile, in the case of coexisting many IEEE 802.15.4-based WBAN, signal interference and collision are the main cause that is decreasing data reliability. but IEEE 802.15.4 Standard does not consider about coexistence of many networks. so it needs improvement. In this paper, To solve about this problem, identify coexistence problem of IEEE 802.15.4-based WBAN by preliminary experiments. and propose a scheme to mitigate the reliability decrease at multiple coexistence WBAN. The proposed scheme can be classified in two steps. The first step is avoidance to collision on the CFP through improving data transmission. The second step is mitigation collision through converting channel access method. Proposed scheme is verified the performance by performing comparison experiment with Standard-based WBAN.

• Magazine of the Korea Concrete Institute
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• v.11 no.2
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• pp.261-270
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• 1999

In these days, construction activities have caused civil petitions associated with vibration-induced damages or nuisances. Therefore, it is strongly needed to develop a remedial technique to mitigate unfavorable effects. The objective of this experimental research is to investigate material and structural dynamic characteristics of vibration-controlled concretes which have been proportionally mixed with various vibration reducing material, such as latex, rubber powder, plastic resin, polystyrofoams and etc. Normal and high strength concrete specimens are also prepared for corresponding comparison. As part of the recycling research for obsolete rubber and plastic materials, 32 concrete cylinders and 10 concrete flexural beams have been made for material and structural dynamic properties, respectively. In accordance with the resonance test on concrete cylinders, it can be concluded that concrete with vibration-reducing material have relatively larger material damping ration than normal or high strength concrete. Styrofoam is determined to be very effective vibration-reducing mixtures. From the vibration test on 10 concrete flexural beams, meamwhile, of importance observations was that material damping ratio is very smaller than structural damping ratio of corresponding specimen. But further vibration test on more flexural beams should be strongly needed by varying support conditions.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.63-63
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• 2003

플라즈마 공정은 DRAM, 이종접합 양극성 트랜지스터(HBTs), 레이저, 평면도파로(planar lightwave circuit)와 같은 전자소자 및 광조자 제작에 있어서 핵심 공정중의 하나이다. 최근 미세 구조의 크기가 극도로 감소하게 됨에 따라 실제 소작 제작에 있어서 미세한 모양을 식각하는 공정이 매우 중요하게 되었다. 그 중에서 고밀도 유도결합 플라즈마(high density inductively coupled plasma)를 이용한 기술은 빠르고 정확한 식각률, 우수한 식각 균일도와 높은 재현성 때문에 습식식각 기술보다 선호되고 있다. 본 연구는 평판형(planar) 고밀도 유도결합 플라즈마 식각장치를 이용하여 BCl$_3$와 BCl$_3$/Ar 플라즈마에 따른 AlGaAs/GaAs의 식각결과를 비교 분석하였다. 공정 변수는 ICP 소스(source power)파워, RIE 척(chuck) 파워, 공정 압력, 그리고 Ar 조성비(0-100%)이었다. BCl$_3$에 Ar을 첨가하게 되면 순수한 BCl$_3$ 플라즈마에서의 AlGaAs/GaAs 식각률(> 3000 $\AA$/min) 보다 분당 약 1000$\AA$ 이상 높은 식각률(>4000 $\AA$/min)을 나타내었다. 이 결과는 Ar 플라즈마의 이온보조(ion-assisted)가 식각률 증가에 기인한다고 예측된다. 그리고 전자주사 현미경(SEM)과 원자력간 현미경(AFM)을 사용하여 식각 후 표면 거칠기 및 수직 측벽도 둥을 분석하였다. 마지막으로 XPS를 이용하여 식각된 후에 표면에 남아 있는 잔류 성분 분석을 연구하였다. 본 결과를 종합하면 BCl$_3$에 기초한 평판형 유도결합 플라즈마는 AlGaAs/GaAs 구조의 식각시 많은 우수한 특성을 보여주었다.79$\ell/\textrm{cm}^3$, 0.016$\ell/\textrm{cm}^3$, 혼합재료 2는 0.045$\ell/\textrm{cm}^3$, 0.014$\ell/\textrm{cm}^3$, 혼합재료 3은 0.123$\ell/\textrm{cm}^3$, 0.017$\ell/\textrm{cm}^3$, 혼합재료 4는 0.055$\ell/\textrm{cm}^3$, 0.016$\ell/\textrm{cm}^3$, 혼합재료 5는 0.031$\ell/\textrm{cm}^3$, 0.015$\ell/\textrm{cm}^3$, 혼합재료 6은 0.111$\ell/\textrm{cm}^3$, 0.020$\ell/\textrm{cm}^3$로 나타났다. 3. 단일재료의 악취흡착성능 실험결과 암모니아는 코코넛, 소나무수피, 왕겨에서 흡착능력이 우수하게 나타났으며, 황화수소는 펄라이트, 왕겨, 소나무수피에서 다른 재료에 비하여 상대적으로 우수한 것으로 나타났으며, 혼합충진재는 암모니아의 경우 코코넛과 펄라이트의 비율이 70%:30%인 혼합재료 3번과 소나무수피와 펄라이트의 비율이 70%:30%인 혼합재료 6번에서 다른 혼합재료에 비하여 우수한 것으로 나타났으며, 황화수소의 경우 혼합재료에 따라 약간의 차이를 보였다. 4. 코코넛과 소나무수피의 경우 암모니아가스에 대한 흡착성능은 거의 비슷한 것으로 사료되며, 코코넛의 경우 전량을 수입에 의존하고 있다는 점에서 국내 조달이 용이하며, 구입 비용도 적게 소요되는 소나무수피를 사용하는 것이 경제적이라고 사료된다. 5. 마지막으로 악취제거 미생물균주를 접종한 소나무수피 70%와 펄라이트 30%의 혼합재료를 24시간동안 장기간 운전

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.4
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• pp.971-980
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• 2013

System performance improvement through the concentrated residual dispersion per span (RDPS) in special transmission fiber spans in optical transmission links with dispersion management (DM) for wavelength division multiplexed (WDM) transmission is investigated through the comparison with the performance in optical transmission links with uniform RDPS in every fiber spans. It is confirmed that, in optical links with RDPS of 0 ps/nm uniformly distributed in the rest fiber spans, if RDPS of 300 ps/nm and 1,320 ps/nm are concentrated in 5th-13th fiber spans and 6th-13th fiber spans, respectively, then the best performance is obtained. It is also confirmed that optimal net residual dispersion (NRD) controlled by precompensation and postcompensation are 10 ps/nm and -10 ps/nm, respectively, in all two cases, and the effective launching power range below 1 dB eye opening penalty (EOP) in the concentrated RDPS of 300 ps/nm and 1,320 ps/nm are improved by 2 dB and 6 dB than optical transmission links with the uniformly distributed RDPS, respectively.