• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 봄 학술발표회 논문집
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• pp.423-428
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• 2000

This Study was conducted to evaluate structural integrity and crack source location of RC structures strengthened with Carbon Fiber Reinforced Plates using acoustic, Four pont bending tests were carried out RC reinforced with C.F.R.P for the several strengthening specimens, the process of fracture was monitored by Acoustic Emission and duration and energy in AE parameters were analyzed. The location and propagation of crack could be easily determined by monitoring AE, which concluded that AE technique could be a very useful tool to evaluate structural integrity of reinforced RC structure.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
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• pp.435-440
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• 2000

In this study, we aims to develop the machining technology for the ultra precision surface and profile accuracy. For this purpose, we construct the electrolytic in process grinding system (ELID grinding) and apply to the cylindrical and internal grinding. Through the various machining experiments such as SCM steel., ceramics, tungsten carbide etc., we have obtained nanometer surface roughness. And we have applied this mirror grinding technique to hydraulic manual valve and mold core of mini disk optical pick-up base. For the development of fine mechanical part machining technology, e have made multi fiber optical connector using fine grinding technology. And constructed micro drilling system with process monitoring system which is possible to drill 50${\mu}{\textrm}{m}$ diameter hole.

• 한국국방경영분석학회지
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• 제22권2호
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• pp.126-138
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• 1996

The statistical control chart has been proven to be the effective tool most widely used in the manufacturing industry for monitoring and controlling the manufacturing processes. However, the Shewhart chart sometimes gives us false information when the distribution of quality characteristics is skewed. Therefore, it cannot serve as the universal quality control chart if there exist odd events in the manufacturing process. The objective of this study is thus to develop the new technique for constructing the limits of quality control chart based on a sample median and range when the distribution of the underlying population is skewed. This new control chart can effectively solve and manage the processes which have the non-normally distributed quality characteristics frequently occurring in the practical situation.

• 한국표면공학회지
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• 제48권4호
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• pp.179-184
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• 2015

Quadrupole Mass Spectrometers (QMS) is a very useful tool in vacuum process diagnosis. Tungsten filament based ion sources are vulnerable to contamination from process gas monitoring. Common symptoms of quadrupole mass spectrometer malfunction is appearance of unwanted contaminant mass peaks or no detection of any ion peaks. We disassembled used quadrupole mass spectrometer and found out black insulating deposits on inside of ion source parts. Five steps of cleaning procedure were applied and almost full restoration of functions were confirmed in two types of closed ion source quadrupole mass spectrometer. By using a numerical modeling (CFD-ACE+) technique, the electric potential profile of ion source with/without insulating deposit was calculated and showed the possibility of quadrupole mass spectrometer malfunction by the deterioration of designed potential profile inside the ion source.

• Mass Spectrometry Letters
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• 제10권3호
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• pp.71-78
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• 2019

For several decades, cancer has been the primary cause of mortality worldwide. New diagnosis and regimens have been developed to improve the chemotherapeutic efficacy and the quality of life of the patients. However, cancer tissues are complex and difficult to assess. Understanding the various properties of the tumor and its environment is crucial for cancer and pharmaceutical research. Several analytical techniques have been providing new insights into cancer research. Recently, matrix-assisted laser desorption ionization (MALDI)-mass spectrometry imaging (MSI), an advanced analytical technique, has been applied to translational research. Proteomic and lipidomic profiling obtained by MALDI-MSI has been critical for biomarker discovery and for monitoring heterogenous tumor tissues. In this review, we discuss technical approaches, benefits and recent applications of MALDI-MSI as a valuable tool in cancer research, namely for diagnosis, therapy, prognosis.

• Smart Structures and Systems
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• 제2권2호
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• pp.141-154
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• 2006

Recently, the Hilbert-Huang transform (HHT) has gained considerable attention as a novel technique of signal processing, which shows promise for the system identification and damage detection of structures. This study investigates the effectiveness and accuracy of the HHT method for the system identification and damage detection of structures through a series of experiments. A multi-degree-of-freedom (MDOF) structural model has been constructed with modular members, and the columns of the model can be replaced or removed to simulate damages at different locations with different severities. The measured response data of the structure due to an impulse loading is first decomposed into modal responses using the empirical mode decomposition (EMD) approach with a band-pass filter technique. Then, the Hilbert transform is subsequently applied to each modal response to obtain the instantaneous amplitude and phase angle time histories. A linear least-square fit procedure is used to identify the natural frequencies and damping ratios from the instantaneous amplitude and phase angle for each modal response. When the responses at all degrees of freedom are measured, the mode shape and the physical mass, damping and stiffness matrices of the structure can be determined. Based on a comparison of the stiffness of each story unit prior to and after the damage, the damage locations and severities can be identified. Experimental results demonstrate that the HHT method yields quite accurate results for engineering applications, providing a promising tool for structural health monitoring.

• Geomechanics and Engineering
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• 제16권5호
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• pp.539-545
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• 2018

Longitudinal Displacement Profile (LDP) is an appropriate tool for determination of the displacement magnitude of the tunnel walls as a function of the distance to the tunnel face. Some useful formulations for calculation of LDP have been developed based on the monitoring data on site or by 3D numerical simulations. However, the presented equations are only based on the tunnel dimensions and for different quality of rock masses proposed a unique LDP. In the present study, it is tried to present a new formulation, for calculation of LDP, on the basis of Rock mass quality. For this purpose, a comprehensive numerical simulation program was developed to investigate the effect of rock mass quality on the LDP. Results of the numerical modelling were analyzed and the least square technique was used for fitting an appropriate curve on the derived data from the numerical simulations. The proposed formulation in the present study, is a logistic function and the constants of the logistic function were predicted by rock mass quality index (GSI). Results of this study revealed that, the LDP curves of the tunnel surrounded by rock masses with high quality (GSI>60) match together; because the rock mass deformation varies over an elastic range.

• Applied Microscopy
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• 제50권
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• pp.25.1-25.11
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• 2020

Scanning acoustic microscopy (SAM) or Acoustic Micro Imaging (AMI) is a powerful, non-destructive technique that can detect hidden defects in elastic and biological samples as well as non-transparent hard materials. By monitoring the internal features of a sample in three-dimensional integration, this technique can efficiently find physical defects such as cracks, voids, and delamination with high sensitivity. In recent years, advanced techniques such as ultrasound impedance microscopy, ultrasound speed microscopy, and scanning acoustic gigahertz microscopy have been developed for applications in industries and in the medical field to provide additional information on the internal stress, viscoelastic, and anisotropic, or nonlinear properties. X-ray, magnetic resonance, and infrared techniques are the other competitive and widely used methods. However, they have their own advantages and limitations owing to their inherent properties such as different light sources and sensors. This paper provides an overview of the principle of SAM and presents a few results to demonstrate the applications of modern acoustic imaging technology. A variety of inspection modes, such as vertical, horizontal, and diagonal cross-sections have been presented by employing the focus pathway and image reconstruction algorithm. Images have been reconstructed from the reflected echoes resulting from the change in the acoustic impedance at the interface of the material layers or defects. The results described in this paper indicate that the novel acoustic technology can expand the scope of SAM as a versatile diagnostic tool requiring less time and having a high efficiency.

• 생태와환경
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• 제56권3호
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• pp.196-206
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• 2023

하천생태계의 주요 1차 생산자인 부착돌말류는 대부분 세포 크기가 매우 작아 관찰과 피각 계수에 고배율의 현미경적 방법을 요구하며, 그로 인해 정성적, 정량적 분석에 있어 정확도와 정밀도를 확보하기가 쉽지 않다. 본 연구는 부착돌말류를 이용한 수생태계 조사·평가에 있어 정도관리를 향상시키기 위한 방법을 제안하였다. 정도관리의 목적에 부합하기 위해, 정성 및 정량분석이 동시에 가능한 영구표본 슬라이드의 분석도구를 신규로 개발하였다. 영구표본을 제작함에 있어 커버 글라스와 슬라이드 글라스에 격자 유무의 조합으로 표본을 만들어 상호 특성을 비교하였다. 그 결과, 다른 시험 조건에 비해 유색선형 격자 슬라이드를 사용하는 방법이 가장 효과적이었다. 향후, 더 개선된 방법의 개발이 기대되지만, 본 연구에서 개발된 방법은 그 효율성과 적용성에 있어 기존 부착돌말류의 실내분석 정도관리를 개선하는 데 기여할 수 있을 것으로 판단된다.

• 정보보호학회논문지
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• 제28권5호
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• pp.1197-1207
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• 2018

파워셸은 닷넷 프레임워크를 기반에 둔, 커맨드 라인 셸이자 스크립트 언어로, 그 자체가 가진 다양한 기능 외에도 윈도우 운영체제 기본 탑재, 코드 은닉 및 지속의 수월함, 다양한 모의 침투 프레임워크 등 공격 도구로서 여러 이점을 가지고 있다. 이에 따라 파워셸을 이용하는 악성코드가 급증하고 있으나 기존의 악성코드 탐지 기법으로 대응하기에는 한계가 존재한다. 이에 본 논문에서는 파워셸에서 실행되는 명령들을 관찰할 수 있는 개선된 모니터링 기법과, Convolutional Neural Network(CNN)을 이용해 명령에서 특징을 추출하고 실행 순서에 따라 Recurrent Neural Network(RNN)에 전달하여 악성 여부를 판단하는 딥 러닝 기반의 분류 모델을 제안한다. 악성코드 공유 사이트에서 수집한 파워셸 기반 악성코드 1,916개와 난독화 탐지 연구에서 공개한 정상 스크립트 38,148개를 이용하여 제안한 모델을 5-fold 교차 검증으로 테스트한 결과, 약 97%의 True Positive Rate(TPR)와 1%의 False Positive Rate(FPR)로 모델이 악성코드를 효과적으로 탐지함을 보인다.