비선형 분석에 의한 뇌파 아티펙트 검출 알고리즘

김철기,박준모,김남호,Kim, Chul-Ki,Park, Jun-Mo,Kim, Nam-Ho 한국융합신호처리학회 2020 융합신호처리학회 논문지 (JISPS) Vol.21 No.1

수술 중 마취 깊이를 측정하는 방법으로 뇌파를 이용한 다양한 파라미터들이 사용되고 있으며, 실제 임상에서는 선형분석 기법 중 하나인 SEF가 널리 사용되고 있다. 그러나 최근 EEG를 포함한 생체학적 신호는 비선형 성질을 가지고 있다는 연구결과가 발표되면서, 이를 기반으로 한 파라미터 개발이 이뤄지고 있다. 본 연구에서는 보다 정확한 EEG 측정과 분석을 위해 비선형 분석 기법 기반의 파라미터를 개발과 이에 대한 정현파 분석을 통한 데이터와의 비교 분석을 통해 수술 중 전자장비와 EEG 계측 시 혼입될 수 있는 노이즈를 추출하고자 한다. Various parameters are used to measure anesthetic depth during surgery using brain waves, and in actual clinical use, the linear analysis SEF is widely used. However, with recent studies showing that biological signals including EEG, contain nonlinear properties interest in nonlinear analysis of brain signals is increasing and parameters based on these are being developed. In this study, we are going to develop a parameter that can measure EEG using the nonlinear analysis method and extract noise that can be mixed with external electronic equipment and EEG instrumentation by comparing it with the data from the bispectrum analysis of static waves.

수질 모니터링을 위한 유해 물질 유입에 따른 생물체의 행동 반응 분석 및 인식

김철기,차의영,Kim, Cheol-Ki,Cha, Eui-Young 한국정보처리학회 2002 정보처리학회논문지B Vol.9 No.5

본 논문에서는 자동 추적 시스템을 이용하여 카바메이트 계열의 농약인 카보퓨란의 치명적인 투여에 대하여 반자연적인 조건에서 반응하는 깔따구의 움직임을 관찰하였다. 4령기에 있는 깔따구를 $6cm\times{7cm}\times{2.5cm}$ 크기의 서식 장소와 $18^\circ{C}$의 수온, 명기와 암기를 각각 10시간, 14시간의 조건에서 관찰을 하였다. 추적 시스템은 깔따구 몸체의 부분 점들을 탐지하여 추적하도록 하였다. 모든 실험은 반자연적인(semi-natural) 상태에서 진행되었으며 약제 카보퓨란(Carbofuran 0.1mg/l) 처리 전 후 이틀씩 모두 4일에 걸쳐서 연속적으로 진행되었다. 실험 결과 약제의 처리후에 압축된 지그제그 형태로 나타나는 "떨림 현상"과 같은 비정규적인 행동들이 종종 나타남을 알 수 있었다. 약제 처리된 종들의 행동 변화를 탐지하기 위하여, 웨이블릿 분석이 다른 움직임 패턴들을 특징화하기 위하여 사용되었다. 이산 웨이블릿에 기반하여 추출된 파라미터들은 약제처리 전후의 움직임에 대한 다른 유형의 패턴들을 표현하기 위하여 인공 신경망을 통하여 학습되었다. 이러한 웨이블릿과 인공 신경망의 통합 모델은 특징화된 움직임 패턴들의 발생 시점을 탐지할 수 있었으며, 수질 모니터링을 위한 독성 물질의 유입을 자동으로 탐지할 수 있는 도구로써 사용될 수 있음을 알 수 있었다.을 알 수 있었다. In this paper, Using an automatic tracking system, behavior of an aquatic insect, Chironomus sp. (Chironomidae), was observed in semi-natural conditions in response to sub-lethal treament of a carbamate insecticide, carbofuran. The fourth instar larvae were placed in an observation cage $(6cm\times{7cm}\times{2.5cm)}$ at temperature of $18^\circ{C}$ and the light condition of 10 time (light) : 14 time (dark). The tracking system was devised to detect the instant, partial movement of the insect body. Individual movement was traced after the treatment of carbofuran (0.1ppm) for four days 2days : before treatment, 2 days : after treatment). Along with the other irregular behaviors, "ventilation activity", appearing as a shape of "compressed zig-zag", was more frequently observed after the treatment of the insecticide. The activity of the test individuals was also generally depressed after the chemical treatment. In order to detect behavioral changes of the treated specimens, wavelet analysis was implemented to characterize different movement patterns. The extracted parameters based on Discrete Wavelet Transforms (DWT) were subsequently provided to artificial neural networks to be trained to represent different patterns of the movement tracks before and after treatments of the insecticide. This combined model of wavelets and artificial neural networks was able to point out the occurrence of characteristic movement patterns, and could be an alternative tool for automatically detecting presences of toxic chemicals for water quality monitoring. quality monitoring.

Additive Regression Models for Censored Data

김철기,Kim, Chul-Ki The Korean Society for Quality Management 1996 품질경영학회지 Vol.24 No.1

In this paper we develop nonparametric methods for regression analysis when the response variable is subject to censoring that arises naturally in quality engineering. This development is based on a general missing information principle that enables us to apply, via an iterative scheme, nonparametric regression techniques for complete data to iteratively reconstructed data from a given sample with censored observations. In particular, additive regression models are extended to right-censored data. This nonparametric regression method is applied to a simulated data set and the estimated smooth functions provide insights into the relationship between failure time and explanatory variables in the data.

Measurement of Temperature Variation on PHE sensor with Applied Currents using Infrared Thermal Microscope

김기석(G. S. Kim),브라잘알 신하(B. Sihha),유영재(Y.-J. Eu),유윤규(Y. K. Yoo),김건우(K.W. Kim),김동표(D.-P. Kim),김건희(G. H. Kim),김철기(C.G. Kim) 한국정밀공학회 2012 한국정밀공학회 학술발표대회 논문집 Vol.2012 No.5월

구조용 직교 집성판의 면내전단계수 표준측정방법 도출

김지용 ( Ji-yong Kim ),안경선 ( Kyung-sun Ahn ),김민정 ( Min-jeong Kim ),오재원 ( Jaewon Oh ),방성준 ( Sung-jun Pang ),김건호 ( Keon-ho Kim ),김철기 ( Chul-ki Kim ),심국보 ( Kugbo Shim ),오정권 ( Jung-kwon Oh ) 한국목재공학회 2022 한국목재공학회 학술발표논문집 Vol.2022 No.1

With increasing demands for high-rise timber buildings, Cross Laminated Timber (CLT) is widely used for various structural elements. Due to the complexity in structure, tall timber buildings are extremely difficult to design by hand. Therefore, computer-based structural design is required, and in-plane shear modulus for CLT is necessary as an input. However, test standards or methods for measurement of the in-plane shear modulus of CLT are currently not provided or insufficient. In this study, a method using picture frame is proposed for measuring in-plane shear modulus, since picture frame could transfer crosshead load into the pure shear stress of the specimen. In this research, acrylic sheet, plywood panel and CLT panel were used as test specimens. Load was transferred from the universal testing machine(Instron) to the acrylic sheet and plywood via dowels, CLT via lag screws because of the thickness of the CLT panel. The acrylic sheet, which is an isotropic material, was tested to determine the measuring area and verify pure shear state occurred by the picture frame. Displacements were measured in both directions (active and passive), and both sides (front and back). In-plane shear modulus of acrylic sheet was evaluated with measured displacements and loads to compare with the literature values. The plywood panel was tested to determine the test protocol, and two stage load cycle test protocol was suggested. CLT panel was tested according to the determined measuring area and test protocol. Evaluated in-plane shear modulus of CLT was 693 MPa and it was found that the picture frame test method is appropriate for the stiff massive wood panel.

구조용 직교 집성판의 면내전단계수 측정방법

김지용 ( Ji-yong Kim ),임형석 ( Hyungsuk Lim ),안경선 ( Kyung-sun Ahn ),방성준 ( Sung-jun Pang ),김민정 ( Min-jeong Kim ),심국보 ( Kugbo Shim ),김건호 ( Keon-ho Kim ),김철기 ( Chul-ki Kim ),오정권 ( Jung-kwon Oh ) 한국목재공학회 2021 한국목재공학회 학술발표논문집 Vol.2021 No.2

With increasing demands for high-rise timber buildings, Cross Laminated Timber (CLT) is widely used for various structural elements. Due to the complexity in structure, tall timber buildings are extremely difficult to design by hand. Therefore, computer-based structural design is required, and in-plane shear modulus for CLT is necessary as an input. However, any test standards are not providing even method for measurement of in-plane shear modulus on CLT or other massive wood panels. In this study, a method using picture frame is proposed for measuring in-plane shear modulus. A 20mm thick acrylic sheet was also tested to determine the range of pure shear, using digital image correlation (DIC) technique. Prior to CLT test, load is transferred to the acrylic panel through dowels. Displacements were measured in both directions (active and passive), and both sides (front and back). With measured displacements and loads, in-plane shear modulus was calculated. It was found that the picture frame test method is appropriate for the stiff massive wood panel.

밭작물소비수량(作物消費水量)에 관한 기초적(基礎的) 연구(硏究)(II) -마늘 및 오이-

김철기 ( Kim Choul Kee ),김진한 ( Kim Jin Han ),정하우 ( Jung Ha Woo ),최홍규 ( Choi Hong Kyu ),권영현 ( Kwun Yong Hyun ) 한국농공학회 1989 韓國農工學會誌 : 전원과 자원 Vol.31 No.3

The purpose of this study is to find out the basic data for irrigation plans of garlic and cucumber during the growing period, such as total amount of evapotranspiration, coefficients of evapotranspiration at each growth stage, the peak stage of evapotranspiration and the maximum evapotranspiraton, optimum irrigation point, total readily available moisture, and intervals of irrigation date. The plots of experiment were arranged with split plot design which were composed of two factors, irrigation point for main plot and soil texture for split plot, and three levels ; irrigation points with pF 1.7~2.1, pF 2.2~2.5, pF 2.6~2.8, for garlic and those with pF 1.9, pF 2.3, pF 2.7, for cucumber, soil textures of silty clay, sandy loam and sandy soil for both garlic and cucumber, with two replications. The results obtained are summarized as follows 1. There was the highest significant correlation between the avapotranspiration of garlic and cucumber and the pan evaporation, beyond all other meteorological factors considered, as mentioned in the previous paper. Therefore, the pan evaporation is enough to be used as a meteorological index measuring the quantity of evapotranspiration. 2. 1/10 probability values of maximum total pan evaporation during growing period for garlic and cucumber were shown as 495.8mm and 406.8mm, respectively, and those of maximum ten day pan evaporation for garlic and cucumber, 63.8mm and 69.7mm, respectively. 3. The time that annual maximum of ten day pan evaporation can be occurred, exists at any stage between the middle of May and the late of June(harvest period) for garlic, and at any stage of growing period for cucumber. 4. The magnitude of evapotranspiration and of its coefficient for garlic and cucumber was occurred in the order of pF 1.7~2.1>pF 2.2~2.5>pF 2.6~2.8 and of pF 1.9>pF 2.3>pF2.7 respectively in aspect of irrigation point and of sandy loam>silty clay>sandy soil in aspect of soil texture for both garlic and cucumber. 5. The magnitude of leaf area index was shown in the order of pF 2.2~2.5>pF 1.7~2.1>pF 2.6~2.8 for garlic and of pF 1.9>pF 2.3>pF 2.7 for cucumber in aspect of irrigation point, and of sandy loam>sandy soil>silty clay in aspect of soil texture for both garlic and cucumber. 6. 1/10 probability value of evapotranspiration and its coefficient during the growing period for garlic were shown as 391.7mm and 0.79 respectively, while those of cucumber, 423.lmm and 1.04 respectively. 7. The time the maximum evapotranspiration of garlic can be occurred is at the date of thirtieth before harvest period and the time for cucumber is presumed to be at the date of sixtieth to seventieth after transplanting, At that time, 1/10 probability value of ten day evapotranspiration and its coefficient for garlic is presumed to be 65.lmm and 1.02 respectively, while those of cucumber, 94.8mm and 1.36 respectively. 8. In aspect of irrigation point, the weight of raw garlic and cucumber were increased in the order of pF 2.2~2.5>pF 1.7~2.1>pF 2.6~2.8 and of pF 1.9>pF 2.3>pF 2.7 respectively. Therefore, optimum irrigation point for garlic and cucumber is presumed to be pF 2.2~2.5 and pF 1.9 respectively, when the significance of yield between the different irrigation treatments is considered. 9. Except the mulching period of garlic that soil moisture extraction patterns were about the same, those of garlic and cucumber have shown that maximum extraction rate exists at 7cm deep layer at the beginning stage after removing mulching for garlic and at the beginning stage of growth for cucumber and that extraction rates of 21cm to 35cm deep layer are increased as getting closer to the late stage of growth. 10. Total readily available moisture of garlic in silty clay, sandy loam, sandy soil become to be 18.71~24.96mm, 19.08~25.43mm, 10.35~13.80mm respctively on the basis of the optimum irrigation point with pF 2.2~2.5, while that of cucumber, 11.81mm, 12.03mm, 6.39mm respectively on the basis of the optimum irrigation point with pF 1.9. 11. The intervals of irrigation date of garlic and cucumber at the growth stage of maximum consumptive use become to be about three and a half days and one and a half days respectively, on the basis of each optimum irrgation point.

식양토질(埴壤土質) 논에서의 관개방식(灌漑方式)과 배수구(排水溝)깊이에 관(關)한 연구(硏究)(3) -포장건조도면(圃場乾燥度面)에서-

김철기 ( Choul Kee Kim ) 한국농공학회 1970 韓國農工學會誌 : 전원과 자원 Vol.12 No.3

粘質土는 湛水狀態下에서는 매우 軟弱하여 짙으로 排水不良한 粘質土의 논에 있어서는 耕耘 播種 收穫등 作業에 있어서 機械進入이 어렵게 되어 農業機械化가 어렵게 되는 것이다. 이 農業機械化를 可能토록 하기 위하여는 機械構造變更에 依한 單位接地荷重의 減少도 考慮되어야 하겠지만 作業의 能率面에서 考慮할 때 畓面의 地耐力增進이 무엇보다도 重要視되고 先行시켜야 할 問題인 것이다. 同一 土性을 지닌 土壤에서의 地耐力은 自然狀態下에서 그 土壤의 乾燥度에 左右되는 것임으로 本報에서는 畓面의 乾燥가 灌漑方式 및 排水溝깊이의 差異에 依하여 어떠한 狀態로 進行되는가를 土壤의 含水比 및 그 假比重의 面에서 調査究明한바 若干의 結果를 얻었기에 이에 報告한다. The Purpose of this study is to find out effective irrigation method and optimum depth of drainage ditch for better growth and yields of rice, improvement of soil permeability, increase in irrigation efficiency, and increase in drying progress of surface soil in paddy field with clay loam soil. In this study a paddy field following treatments were ployed in carrying out the field experiment: Test plots were laid out by split plot design with four replica two main plots were designated as A₀ and A₁ according to the differenc in irrigation method i. e. continuous and intermittent flooding applied during the last half of rice growing season, respectively. Each main test plots had five sub-plots which were designated as B₀, B₁, B₂, B₃, and B₄ according to the difference in deph of drain i. e. 10 cm, 20 cm, 40 cm, 60 em, and 80 cm respectively. In addition, the soils of the plots were kept in, condition for about 2 months before transplanation of seedlings. To compare with the effect obtained in the Bo sub-plot, another plot designated as B¹₀ another plot designated as Bo that was not provided with a drain and was flooded for two months before planting was laid out with four replications. As a resut, the author obtained the following results in this experiment which was carried out in 1968; 1. As to better growth and yield of rice. (1) The progress of the dryness of surface soil in test plots is rapid in proportion to the increase in the depth of drain. (2) The height of rice plants in both continuous and intermittent flooding plots shows to be increased in proportion to the depth of drain through growing season, but to be almost constant for- the depths of 60 cm and 80 cm. Plant height and growing rate in the intermittent flooding plants surpassed those in the continuous flooding plots at the last half stage of the growing season. (3) The numbers of stalks are almost the same in the plots having the same depth drains during the first half of growing season, but are increased in proportion to the depth of drain. The numbers of valid stalks in the intermittent flooding plots generally surpasseds that in the continuous flooding plots, except that in polt (Bo) with zero-cm depth of drain at the last half stage. On the other hand, it is increased with the increase in the depth of drain in any plot and becomes almost constant at Ploto B₃ and B₄. (4) The weight of raw rice grains in the intermittent flooding, plot is 3 to 4 % heavier than that in the continuous irrigation plot, and at Plot B₂, about 13 % heavier than that at Plot B₀. Also the increase in the field is in proportion to the depth of drain. The yiled shows highly significant correlation between the variation of irrigation method and between Plot B₀ and the other plots of B₁,B₂, B₃, B₄ and insignificant between Plots B₀ and B¹₀. (5) The optimum depth of drain according to this experiment was about 40 cm from a view point of rice production, but it may depend on depth of surface crack in paddy field so far as ground water table becomes low. 2. In the aspect of improving soil permeability and increasing irrigation efficiency. (1) The amount of percolation at any plot showed the tendency of increasing in proportion to the depth of drain through the growing period. And the soil permeability at the intermittent floo-ding plot in the last half stage of growing season is considerably greater than that in the first half stage and that at the continuous irrigation plot. (2) The weight of raw rice grains increases with the increase of permeability and became maximum at a permeability mid-term drainage in the test plots. (3) The greater the depth of drain the more is the amount of irrigation water consumed. Up to the 20 cm depth of the drain, the amount of irrigation water in the intermittent irrigation plot is considerally less than that in the continuous irrigation plat, while in the intermittent irrigation plot where the drain depth was more than 40 cm, water is consumed to be out of proportion to the depth. (4) The efficiency of irrigation water is maximum in the intermittent irrigation plot where the depth of drain was 0 cm or 20cm,secondary in the conventional irrigation plot where the depth was 20cm to 40 cm and in the plot B¹₀ and minimum in the iner-mittent irrigation plot with the 80 cm-depth drain. (5) The irrigated frequency was much the same between the plots with equal depth of the drain during the first half of growing season when the continuous flooding irrigation method was only used, but the frequency in the intermittent flooding plots was less than that in the continuous flooding ones duirng the last half of growing season. 3. In the aspect of increasing drying progress of surface soil. (1) The apparent specific gravity of the soil has the maximum value near the plastic limit, showing the decreasing tendency below or above the limit, especially linearly decreasing at the soil moisture content over the limit. (2) A limit of forming non-capillary porosity due to macro-aggregated formation in the clay loam mao occur at the plastic limit. Therefore, the soil maisture content making the paddy field dry to improve the hydraulic conductivity of soil and to make the root growth depth might be below the plastic limit. (3) The progress of the dryness of surface soil in the plot is rapid in proportion to the increase in the depth of drain. It was more rapid in the intermittent irrigation plot than in the continuous flooding irrigtaon plot.

구조용 PB를 적용한 경골벽체의 전단성능에 관한 연구

김철기 ( Chul-ki Kim ),이민 ( Min Lee ),김광모 ( Kwang-mo Kim ),심국보 ( Kugbo Shim ) 한국목재공학회 2021 한국목재공학회 학술발표논문집 Vol.2021 No.2

우리나라 목조건축 시장은 지속적으로 성장하여, 2011년 이후 연간 1만여 동이 꾸준히 착공되고 있다. 그러나 목조건축의 대부분은 수입재를 사용하는 경골 목조건축에 국한되어 있어, 수입재를 대체할 수 있는 방안에 대한 연구가 필요하다. 이에 국립산림과학원에서는 구조용 PB를 개발하여 경골 목조건축에서 구조용 판상재로 사용되는 수입 OSB를 대체하고자 한다. 구조용 PB를 적용한 경골 벽체의 전단 성능을 평가하기 위하여 크기 2.44(길이)×2.44(높이) m 벽체를 제작하였다. 벽체에서 골조는 육안 등급 2등급의 2×6 SPF 제재목을 사용하였으며, 스터드 간격은 406, 610 mm로 하여 2 종류의 벽체를 제작하였다. 벽체의 판상재로 구조용 PB와 OSB를 벽체 하나 당 2개씩 판상재 내부와 외곽에 각각 300, 150 mm 간격으로 8d 못을 박아 설치하였다. 전단 성능은 준정적 하중(ISO 16670 프로토콜)을 가하여 얻어진 하중이력곡선을 이용하여 평가하였다. OSB 벽체의 경우, 스터드 간격 406, 610 mm에서 전단 내력은 9.6, 7.9 kN/m로 나타났다. 구조용 PB 벽체의 경우, 스터드 간격 406, 610 mm에서 전단 내력은 8.5, 8.6 kN/m로 확인하였다. 동일한 벽체 구성에서 건축구조기준 내 허용 전단 내력은 7.1 kN/m로 실험한 벽체 모두 상회하였다. 스터드 간격 610 mm에서 OSB 벽체에 비하여 구조용 PB벽체의 전단 내력이 높게 나타났는데 이는 구조용 PB를 사용한 못 접합부의 전단 내력이 높기 때문이라고 사료된다. 다만 스터드 간격 406 mm에서는 전단 내력의 증가를 확인할 수 없었는데, 이는 벽체 외곽의 접합부에서 접합부 최대 내력에 도달하기 전에 파괴가 발생하였기 때문이라고 판단된다. 추후 구조용 PB의 못 접합부에 대한 연구를 통해 구조용 PB 벽체의 전단 내력 성능을 향상시킬 수 있는 방안을 마련하고자 한다.

Wavelet에 의한 주파수 영역 내에서의 디지털 워터마크의 삽입 및 검출 기법

김철기(Cheol-Ki Kim),강이철(Yi-Chul Kang),이학만(Hak-Man Lee),차의영(Eui-Young Cha) 한국멀티미디어학회 2000 한국멀티미디어학회 학술발표논문집 Vol.2000 No.1