• 한국공작기계학회논문집
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• 제15권4호
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• pp.44-48
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• 2006

Recently, demand the ultra precision product which is increasing rapidly is used extensively frontier industry field such as semi-conductor, computer, aerospace, precision machine. Ultra precision processing is the portion that is very needed to NT in the field of mechanical engineering. The latest date, together with radical advancement of electronic and photonics industry, necessity of ultra precision processing is on the increase for the manufacture of various kernel parts those are connected with these industrial fields. Specially, require motion accuracy of high resolution of nm order in stroke of hundreds millimeters according as diameter of processing object great and processing accuracy rises. In this case ,the response speed absolute delay because inertial mass of moving part is very large. Therefore, real time motion error compensation becomes very hardly. In this paper, we used ultra precision cutting unit(UPCU) to cope such problem. a UPCU is designed and tested to obtain sub-micrometer from accuracy in diamond turning of flat surfaces. The thermal growth spindle error is compensated for real time using a UPCU driven by piezoelectric actuator along with a laser encoder displacement sensor.

• 지구물리와물리탐사
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• 제6권2호
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• pp.71-76
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• 2003

정확한 초동 발췌는 고해상 속도 토모그램 도출에 중요한 요소이다. 주시 발췌의 정확도에 영향을 주는 2가지 요인은 지질학적 요인과 기계적인 요인이 있다. 중요한 기계적인 요인은 발파시간 제어이다. 임펄시브형 시추공 탄성파 송신원에 의한 기록에서 다음과 같은 문제가 확인되었다. 즉, 불규칙한 발파시간 제어 문제와 기록에 나타난 발파시간의 불확실성이다. 이러한 발파시간 문제는 발췌된 초동에 정확도를 저하시키게 되며, 따라서 속도 토모그램을 왜곡시키게 된다. 본 연구에서는 수평방향의 속도와 NMO 속도를 반복적으로 비교함으포써 최적의 발파시간을 산출하는 방법을 제시하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.107.1-107.1
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• 2014

We have developed and commercialize a time-of-flight - medium energy ion scattering spectrometry (TOF-MEIS) system (model MEIS-K120). MEIS-K120 adapted a large solid acceptance angle detector that results in high collection efficiency, minimized ion beam damage while maintaining a similar energy resolution. In addition, TOF analyzer regards neutrals same to ions which removes the ion neutralization problems in absolute quantitative analysis. A TOF-MEIS system achieves $7{\times}10^{-3}$ energy resolution by utilizing a pulsed ion beam with a pulse width 350 ps and a TOF delay-line-detector with a time resolution of about 85 ps. TOF-MEIS spectra were obtained using 100 keV $He^+$ ions with an ion beam diameter of $10{\mu}m$ with ion dose $1{\times}10^{16}$ in ordinary experimental condition. Among TOF-MEIS applications, we report the quantitative compositional profiling of 3~5 nm CdSe/ZnS QDs, As depth profile and substitutional As ratio of As implanted/annealed Si, Ionic Critical Dimension (CD) for FinFET, Direct Recoil (DR) analysis of hydrogen in diamond like carbon (DLC) and InxGayZnzOn on glass substrate.

• 한국통신학회논문지
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• 제33권11B호
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• pp.981-988
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• 2008

본 논문에서는 MANET에서 효율적인 AODV 알고리즘을 제안한다. MANET에서는 전송 채널이 에러와 손실이 높기 때문에 홉 수를 절대적인 네트워크의 메트릭으로 볼 수 없다는 점이다. 제안된 기법은 크로스레이어 디자인을 이용하여 데이터 링크 계층에서 FER을 주기적으로 측정한 후, 각 노드는 링크 상태의 가중치를 AODV 프로토콜의 예약된 필드로 전송하는 방법을 사용하였다. 효과적인 경로 설정을 위해서 가중치의 합을 비교해서 채널 상태가 양호한 링크를 경로 설정에 사용하도록 설계하였다. 제안된 AODV는 기존 AODV 방식에 비하여 throughput, 라우팅 오버헤드 및 평균 전송 지연시간을 향상시킨다.

• 한국측량학회지
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• 제22권4호
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• pp.401-409
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• 2004

GPS를 이용한 컨데이너 모니터링 시스템은 실시간 물류추적 및 관리시스템이라 할 수 있다. GPS는 컨레이너 위치를 정확하고 신속하게 실시간으로 추적할 수 있는 시스템이다. 항만, 공항 등의 시설관리자는 효을적인 화물의 적재, 하역, 보관이 필요하고, 운송업체 또는 화물주는 최적으로 차량을 배차해야 하며, 화물분실, 운송지연 등의 문제를 사전에 예방하거나 대처할 수 있어야 한다. 본 연구에서는 GPS의 측위기법중 실시간 이동 측위 기법을 이용하여 컨테이너의 위치 및 경로를 추적하고, 실시간으로 관측함으로써 상차지에서 하차지까지의 절대위치 및 상대위치를 수치적이고 시각적으로 모니터링하였으며 컨데이너의 이동이나 정지시의 위치 정확도를 분석하였다.

• 한국화재소방학회논문지
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• 제26권3호
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• pp.85-90
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• 2012

최소자연발화온도는 가연성물질이 주위의 열에 의해 스스로 발화하는 최저온도이다. 최소자연발화온도는 유기혼합물 중 가연성 액체혼합물의 안전한 취급을 위해서 중요한 지표가 된다. 본 연구에서는 ASTM E659 장치를 이용하여 가연성 혼합물인 n-Decane+sec-Butanol 계의 최소자연발화온도를 측정하였다. 2성분계를 구성하는 순수물질인 n-Decane과 sec-Butanol의 최소자연발화온도는 각 각 $211^{\circ}C$, $447^{\circ}C$로 측정되었다. 그리고 측정된 n-Decane+sec-Butanol계의 최소자연발화온도는 제시된 식에 의한 예측값과 적은 평균절대오차에서 일치하였다.

• 자원환경지질
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• 제32권1호
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• pp.53-62
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• 1999

The possibility of heavy metal pollution by contaminated roadside soils was studied under controlled conditions. The soil samples from roadside and those from a retention pond consisting of settling particles were characterized by the XRD analyses and the sequential extraction experiments. Characterization by sequential extraction, for roadside soil indicates elevate total concentrations of heavy metals. The leaching behavior of the samples under different pH and time conditions were also studied. Differences between both types of samples result mainly from the buffering effect of carbonates, present in roadside soils and lacking from settling particles. Acid leaching of the settling particles is equivalent to the sum of FI+FII+FIII, while the amounts leached from roadside soil are lower probably from kinetic reasons. The buffering effects of carbonates were found to greatly delay the onset of the leaching reactions and the extent of dissolution in most metals except for Ca and Mn. The study of leaching kinetics at pH of 6.5 and 5 showed that Cd and Zn reached the maximum possible concentration within 3 days, while Pb did not show any sign of dissolution at both ph values. The absolute amounts of dissolved Cd and Zn increased by 7 to 9 times by decreasing the pH from 6.5 to 5, indicating slightly acidified rain may result in significant metal dissolution. As deduced from both sequential extraction and leaching experiments, the relative mobility of heavy metals is found to be : Mn=Cd>Zn>>Pb>Fe, in spite of large differences in heavy metal contents and localizations.

• 한국통신학회논문지
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• 제25권10B호
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• pp.1732-1743
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• 2000

In this paper a fixed-delay trellis search with decision feedback (FDTrS/DF) for high-density DVD systems (4.7-15GB) is proposed and implemented with FPGA. The proposed FDTrS/DF is derived by transforming the binary tree search structure into trellis search structure implying that FDTrS/DF performs better than the singnal detection techniques based on tree search structure such as FDTS/DF and SSD/DF. Advantages of FDTrS/DF are significant reductions in hardware complexity due to the unique structure of FDTrS composed of only one trellis stage requiring no traceback procedure usually implemented in the Viterbi detector. Also in this paper the PDFS/DF and SSD/DF orginally proposed for high-density magnetic recording systems are modified for the DVD system and compared with the proposed FDTrS/DF. In order to increase speed in the FPGA implementation the pipelining technique and absolute branch metric (instead of square branch metric) are applied. The proposed FDTrS/DF is shown to provide the best performance among various signal detection techniques such as PRML, DFE, FDTS/DF and SSD/DF even with a small hardware complexity.

• 한국가스학회지
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• 제16권2호
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• pp.45-51
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• 2012

최소자연발화온도는 가연성혼합물이 화염이나 스파크 없이 주위로부터 충분한 열에너지를 받아서 스스로 발화하는 최저온도를 말한다. 본 연구에서는 ASTM E659 장치를 이용하여 가연성 혼합물인 n-Pentanol+Ethylbenzene계를 구성하는 순수물질과 혼합물의 최소자연발화온도를 측정하였다. Pentanol과 Ethylbenzene의 측정된 최소자연발화온도는 각 각 $285^{\circ}C$, $475^{\circ}C$ 였다. 그리고 n-Pentanol+Ethylbenzene 계의 예측된 최소자연발화온도는 실험값과 적은 평균절대오차에서 일치하였다.

• 융합신호처리학회논문지
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• 제15권1호
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• pp.1-8
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• 2014

Digital watermarking techniques are attracting attention as a proper solution to protect copyright for multimedia data. This paper proposes a new audio watermarking method based on Discrete Cosine Transformation (DCT) and Discrete Wavelet Transformation (DWT) for copyright protection. In our proposed watermarking method, the original audio is transformed into DCT domain and divided into two parts. Synchronization code is applied on the signal in first part and 2 levels DWT domain is applied on the signal in second part. The absolute value of DWT coefficient is divided into arbitrary number of segments and calculates the energy of each segment and middle peak. Watermarks are then embedded into each middle peak. Watermarks are extracted by performing the inverse operation of watermark embedding process. Experimental results show that the hidden watermark data is robust to re-sampling, low-pass filtering, re-quantization, MP3 compression, cropping, echo addition, delay, and pitch shifting, amplitude change. Performance analysis of the proposed scheme shows low error probability rates.