• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.2 s.54
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• pp.137-144
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• 2009

This paper provides the results from evaluating the stiffness of Hi-Form joint by an experiment and the system identification method using the dynamic modal data, and the reasonable modeling method of Hi-Form joint which is proposed for improved stair construction recently. Based on the crack pattern and load-displacement relationship and the damage distribution, it can be judged that Hi-Form joint can't fully transfer the forces between the elements linked, and we propose that the joint is modeled as a element which have a stiffness with 50% decrease.

• Journal of the Microelectronics and Packaging Society
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• v.19 no.1
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• pp.81-87
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• 2012

This paper focuses on three-dimensional measurement system of micro balls on micro Ball-Grid-Array(BGA) packages in-line. Most of visual inspection system still suffers from sophisticate reflection characteristics of micro balls. For accurate shape measurement of them, a specially designed visual sensor system is proposed under the sensing principle of phase shifting moire interferometry. The system consists of a pattern projection system with four projection subsystems and an imaging system. In the projection system, four subsystems have spatially different projection directions to make target objects experience the pattern illuminations with different incident directions. For the phase shifting, each grating pattern of subsystem is regularly moved by PZT actuator. To remove specular noise and shadow area of BGA balls efficiently, a compact multiple-pattern projection and imaging system is implemented and tested. Especially, a sensor fusion algorithm to integrate four information sets, acquired from multiple projections, into one is proposed with the basis of Bayesian sensor fusion theory. To see how the proposed system works, a series of experiments is performed and the results are analyzed in detail.

• Economic and Environmental Geology
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• v.42 no.5
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• pp.509-512
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• 2009

Powder diffraction patterns of the zeolite mesolite ($Na_{5.33}Ca_{5.33}Al_{16}Si_{24}O_{80}{\cdot}21.33H_2O$), with a natrolite framework topology were measured as a function of pressure up to 5.0 GPa using a diamond-anvil cell and a $200{\mu}m$-focused monochromatic synchrotron X-ray. Under the hydrostatic conditions mediated by pore-penetrating alcohol and water mixture, the elastic behavior of mesolite is characterized by continuous volume expansion between ca. 0.5 and 1.5 GPa, which results from expansion in the ab-plane and contraction along the c-axis. Subsequent to this anomalous behavior, changes in the powder diffraction patterns suggest possible reentrant order-disorder transition. The ordered layers of sodium- and calcium-containing channels in a 1:2 ratio along the b-axis attribute to the $3b_{natrolite}$ cell below 1.5 GPa. When the volume expansion is completed above 1.5 GPa, such characteristic ordering reflections disappear and the $b_{natrolite}$ cell persists with marginal volume contraction up to ca. 2.5 GPa. Further increase in pressure leads to progressive volume contraction and appears to generate another set of superlattice reflections in the $3c_{natrolite}$ cell. This suggests that mesolite in the pressure-induced hydration state experiences order-disorder-order transition involving the motions of sodium and calcium cations either through cross-channel diffusion or within the respective channels.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.4
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• pp.156-163
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• 2015

In this paper, we propose an active water level and distance measurement algorithm using a light beam pattern. On behalf of conventional water level gauge types of pressure, float-well, ultrasonic, radar, and others, recently, extensive research for video analysis based water level measurement methods is gradually increasing as an importance of accurate measurement, monitoring convenience, and much more has been emphasized. By turning a reference light beam pattern on bridge or embankment actively, we suggest a new approach that analyzes and processes the projected light beam pattern image obtained from camera device, measures automatically water level and distance between a camera and a bridge or a levee. As contrasted with conventional methods that passively have to analyze captured video information for recognition of a watermark attached on a bridge or specific marker, we actively use the reference light beam pattern suited to the installed bridge environment. So, our method offers a robust water level measurement. The reasons are as follows. At first, our algorithm is effective against unfavorable visual field, pollution or damage of watermark, and so on, and in the next, this is possible to monitor in real-time the portable-based local situation by day and night. Furthermore, our method is not need additional floodlight. Tests are simulated under indoor environment conditions from distance measurement over 0.4-1.4m and height measurement over 13.5-32.5cm.

• Journal of the East Asian Society of Dietary Life
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• v.13 no.6
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• pp.586-592
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• 2003

This research used High Performance Liquid Chromatography(HPLC) to analyze and compare the content and the pattern of chlorophyll to find the difference in quality, water temperature, and the stirring time between the three different types of Korean and Japanese powder green tea, which were currently on the market. Chlorophyll contents of Japanese-made medium quality tea (S5: 8.34mg/g), and low quality tea (S6: 8.23mg/g) were relatively high, and that of Korean-made medium quality tea (S2 ; 4.87mg/g) was lower. The water temperature of 85$^{\circ}C$ and 95$^{\circ}C$ were high except in Korean-made medium and low quality powder green tea (S2 and S3). Japanese-made powder tea required 60 seconds of stirring time and Korean-made tea required 15 seconds, but 30 seconds seem to be the ideal stirring time for both of them. Chlorophyll a, b, pheophytin a, b, and pheophorbide were confirmed from the chlorophyll pattern. There were 1.5∼2 times more of chlorophyll a in Japanese-made one compared to that of Korean-made one; also 1.5∼2 times more of pheophytin a in Korean-made one than Japanese-made one. It might be concluded that Japanese-made powder green tea was higher in quality.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.203-203
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• 2017

IPCC 5차보고서의 기후변화 전망에 따르면 우리나라를 포함한 동아시아 지역의 연강수량은 전반적으로 증가되나, 기온상승, 강우강도 증가 및 강수일수의 감소도 예상되고 있어 극한홍수 및 극한가뭄의 위험성은 높을 것으로 전망되고 있다. 즉, 연강수량 증가에 따른 미래의 용수공급 안정성이 높아지는 것이 아니라 짧은 기간 내 집중호우에 따른 홍수위험성 증가의 의미가 크며, 강수일수 감소 및 기온상승은 증발산량 증가로 실제 저수지에서 활용될 수 있는 물의 양이 감소할 수 있다는 것이다. 국가수자원장기종합계획에서도 미래 극한가뭄의 강도, 규모 및 지속기간이 커질 것으로 전망하고 있어, 국내 용수공급의 대부분을 차지하는 다목적댐의 기후변화 대응 용수공급능력을 평가하여 극한 물 부족에 대한 사전대응계획과 효율적 운영방안을 수립할 필요가 있다. 특히, 국내 다목적댐 저수지 운영은 홍수기(6.20. ~ 9.30.) 유입량 크게 의존하고 있으며, 실제 과거에는 용수공급에 필요한 유입량의 대부분은 홍수기에 유입되었다. 그러나 지난 2015년 소양강댐과 보령댐 지역의 계절별, 지역별 강수패턴 변화와 같이 기후변화 영향에 따른 강수의 시 공간적 변동성 가속화는 다목적댐의 용수공급 불확실성이 갈수록 심화될 수 있음을 시사하고 있다. 따라서 본 연구에서는 AR5기반의 52개 기후변화 시나리오(26개 GCM, 2개의 RCP 시나리오)를 이용하여 낙동강 다목적댐 유입량을 산정한 후, 낙동강 유역 다목적댐의 기후변화 대응 용수공급 안정성을 평가하였다. 결과적으로 기존 관측자료 기반의 다목적댐 가뭄대응 저수지 운영기준은 미래 기후변화에 따른 용수공급 안정성 확보에 어려움이 있을 것으로 예상되며, 기후변화 시나리오를 반영한 가뭄대응 운영기준 개발이 필요한 것으로 분석되었다.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.37-37
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• 2019

기후변화에 따른 강우량 변화는 유역의 수문학적 변화와 하천 침식, 토양유실 등 물리적 변화를 함께 동반하여 유역환경에 영향을 미치게 된다. 최근에도 강우 발생시 집중강우에 의해 짧은 시간에 많은 강우가 발생하여 홍수피해가 발생하고 있으며, 건기시에는 가뭄이 지속되고 있다. RCP 4.5 및 8.5를 활용한 미래 기후시나리오 예측에 따르면 강우량과 증발산량은 증가할 것으로 예측되고 있으나, 우기시의 강수량은 증가하고 건기시의 강수량은 감소하여 계절 간 강수의 불균형이 심화될 것으로 예측되고 있다. 이러한 변화는 강수량, 하천유량, 침투량 등 유역의 수문체계에 영향을 끼치게 되고, 유량의 변화에 따라 하상변동 등 하천형상의 변화가 발생할 수 있으며, 하천 형상변화에 따라 유량이 변화하고, 토사의 유입이 증가하여 수질이 변화하여, 유역 내 유량 및 수질변화에 따른 불확실성이 높아지게 된다. 최근 개발에 의한 불투수면의 증가와 집중호우의 발생으로 인한 유출량 증가에 따라 강우발생시 직접유출량은 증가하고 침투량은 감소하여 우기시에는 홍수 및 침수가 발생하고, 건기시에는 기저유출에 의한 하천유지용수가 감소하여 하천이 건천화되고 수질이 악화 되는 등 물순환 체계가 훼손되고 있다. 강수량과 강우패턴의 변화에 따른 유출량 변화는 유역의 물순환에 직접적인 영향을 미치게 된다. 홍수나 극한강우가 발생할 경우 유역의 수문학적 특성에 따라 직접유출량은 증가하고 상대적으로 침투 및 증발산양은 감소하게 되며, 건기시에는 하천이 건천화 되는 등 물순환 체계가 훼손되고 유량의 변화에 따라 수질 또한 악화될 수 있다. 본 연구에서는 낙동강 유역을 대상으로 기후변화에 따른 유역 유출량 변화 및 하천형상 변화예측을 위해 기후변화 시나리오를 이용하여 하천환경변화에 대한 전망을 예측하고, 유역의 유출량을 구체적으로 분석 할 수 있는 유역모형을 활용하여 유역의 물순환에 미치는 영향을 검토하고 물순환을 고려한 유량 및 수질부하량을 분석하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.10
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• pp.752-757
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• 2018

This study presents the performance evaluation results of a 77-GHz waveguide slot array antenna that was fabricated by attaching a patterned printed circuit board(PCB) on a metal block. The 77-GHz waveguide was divided into a top plate and a bottom structure. The top plate was fabricated using a patterned PCB that can implement a fine slot at low cost. The top cover was then bonded to the bottom metal structure with a waveguide trough using anisotropic conductive film. For evaluating the antenna performance, a $1{\times}16$ slot array antenna was fabricated using our proposed method and the gain and pattern were measured and compared with the simulation results. Though the measurement results demonstrate a reduction in gain of around 2.3~3.5 dB compared to the simulation results assuming ideal bonding conditions, the pattern hardly changed and the slot antenna with a gain of approximately 17 dBi at 77 GHz can be easily manufactured at a low cost using the proposed method.

• Water for future
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• v.25 no.3
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• pp.105-113
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• 1992

The purpose of this paper is to introduce and to apply the artificial neural network theory to real hydrologic system for forecasting daily streamflows during flood periods. The hydrologic dynamic process of rainfall-runoff is identified by the iterated estimation of system parameters that are determined by adjusting the weights of the network according to the non-linear response characteristics which is formed the model. Back propagation algorithm of neural network model is applied for the estimation of system parameters with past daily rainfall and runoff series data, and streamflows are forecasted using the parameters. The forecasted results are analyzed by statistical methods for the comparison with the observed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.5
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• pp.1074-1079
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• 2004

So far, many sensors such as a structured grid pattern generator, a laser, and CCD camera to obtain 3D information have been used, but most of algorithms for a calibration are inefficient since a huge memory and experiment time are required. In this paper, the calibration algorithm of a structured grid pattern based on triangulation method is introduced to calculate 3D information in the real world. The beams generated from structured grid pattern generator established horizontally with the CCD camera are projected on the calibration plat. A CCD camera measures the intersection plane of a projected beam and an object plane. The 3D information is calculated using measured and calibration datum. This proposed method in this paper has advantages such as a memory saving and an efficient experimental time since the 3D information is obtained simply the triangulation method.