• 물과 미래
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• 제15권3호
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• pp.23-36
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• 1982

The stochastic variations and structures of time series data on water quality were examined by employing the techniques of autocorrelation function, variance spectrum, Fourier series, autoregressive model and ARIMA model. These time series included hourly and daily observation on DO, turbidity, conductivity pH and water temperature. The measurement was made by automatic recording instrument at Noryangjin and Dook-do located in the downstream part of Han River during 1975 and 1976. Hourly water quality time series varied with the dominant 24-hour periodicity, and the 12-hour periodicity was also observed. An important factor affecting 24-hour periodic variation of DO is believed to be photosynthesis by algae. These phenomena might be attributable to periodic discharges of municipal sewage. Noryangjin site showed the more distinct 12-hour periodicity than Dook-do site did, and tidal effect might be responsible for the difference. The water quality, as measured by DO and turbidity, was better in the afternoon compared with the quality in the morning. This change can be explained by the periodic variation of DO, temperature and the amount of municipal wewage discharge. It was also observed that the water temperature at Noryangjin was higher than the temperature at Dook-do. This difference might have been caused by the pollutants that were added to the section between two sites. The correlation coefficients between some of the variables were fairly high. For example, the coefficient was -0.88 between DO and water temperature, 0.75 between turbidity and river flow, and 0.957 between water temperature and air temperature. The lag time of heat transfer from the air to the water was estimated as 24 days. The first order auto-regressive model was appropriate for explaning standardized hourly DO time series. The ARIMA model of (1, 0, 0) type provided relatively satisfactory results for daily DO time series after the removal of significant harmonic value.

• 한국지능시스템학회논문지
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• 제24권3호
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• pp.245-250
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• 2014

중독은 크게 매개체 자체가 중독성을 가진 매개성 중독과 매개체 자체가 중독성을 가진 것이 아니라 예민한 개인과 잠재된 어떤 행동과 결합하여 중독을 유발하는 유발성 중독으로 나눌 수 있다. 매개성 중독은 약물 중독, 알코올 중독과 주로 화학물질의 직접 적인 원인이 되어 중독현상을 일으킨다. 유발성 중독은 쇼핑 중독, 일 중독, 게임 중독, 인터넷 중독, TV중독, 도박 중독 등의 사이버 중독이 있다. 유발성 중독은 개인의 감수성의 문제로서 개인에 따른 편차가 존재한다. 본 논문에서는 전기 시스템의 R-L-C 직렬 회로와 기계 시스템의 Spring-Damper-Mass를 이용하여 등가적으로 동일한 2차원의 중독 모델을 제안한다. 제안한 중독 모델에 비선형 항을 추가하여 Duffing을 구성한 후 파라미터 변화에 의해 주기운동과 카오스 운동을 시계열과 위상공간으로 나타내었다. 또한 파라미터 중 통제계수의 변화에 의해 주기 운동은 중독 되기 전의 상태를 카오스 운동은 중독된 상태임을 확인하였다.

• 한국환경복원기술학회지
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• 제12권6호
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• pp.63-75
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• 2009

This study carried out to analysis the characteristics of periodic changes of landscape facilities with the apartment sites in Cheongju City. The construction periods were divided into the introduction stage (the 1980s), the development stage (the 1990s), and the maturity stage (after 1999). As for the apartment sites constructed in the introduction stage (the 1980s), their landscape facilities were restricted to play and resting facilities. Some of them even were constructed without rest facilities. Since the focus was on the affluent supply of houses in the 1980s, they put a greater emphasis on quantity than quality. Entering the development stage in the 1990s, they started to pave the sidewalks and driveways separately within the apartment sites and build parking lots underground. After 1999, they entered the maturity stage, where the outside spaces of apartment sites began to reflect environment-friendly designs and the initiatives to improve residential environments. The major causes behind the introduction of high-grade materials in landscape facilities in the open spaces of apartment sites are the upgraded level of living standards and the diversified patterns of activities taking place in the open spaces. The environmental formative works were placed alongside waterscape spaces to create a beautiful and harmonious landscape.

• 대한지역사회영양학회지
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• 제7권2호
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• pp.266-276
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• 2002

In this study, a computerized nutritional and health guide program for workers was developed. The dietitian at the work site could utilize periodically conducted medical examination data to develop an effective health care counseling model based on the developed Nutritional and Health Guide Program. A personal computer (Pentium II PC MMX-150, 32MB RAM, 2.95 GB HDD) with Microsoft Visual Basic 6.0 Enterprise Edition and Microsoft Access 97 installed, was used. The Nutritional and Health Guide Program consisted of seven main menus and 43 sub-menus. Included in the main menu were Basic Information, Periodic Health Check-ups, Visitors' Consultations, Nutritional/Health Tips, Nutritional Education according to Diseases, Help and Exit. In the Periodic Health Check-up menu, dieticians could input the health examination data of employees and touch for the recommended treatments for diseases such as obesity, diabetes, high cholesterol, hypertension and hepatitis. The Visitors'Consultation menu has been designed to compile health information about the employees who sought consultations. The Nutritional/Health Tips menu was designed to provide 14 kinds of programmed nutritional educational media and information. In the Nutritional Education According to Diseases menu, the dietitian could judge the subject's willingness to obtain treatment based on the Stage of Change Model. According, the content of the administered respective nutritional education was classified by stages. The Help menu, provide a chart of the method and procedure used as nutritional guidelines, by which the results of the health examination were classified as people in good health and those requiring special medical attention. The results of the evaluation of this program showed highly positive rates for usefulness (4.09), convenience (4.04), lettering size (4.02), interest (3.93), design (3.49). It also showed that 97.5% of the subjects thought that this program would be helpful for implementation of their company's nutritional educational program. Therefore, this menu could help dietitians plan, conduct, and evaluate their nutritional guidelines for employees. It is expected that The Nutritional and Health Guide Program developed in this study will play a role as a scientific and effective guide in conjunction with health examination results.

• 전기전자학회논문지
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• 제24권1호
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• pp.1-8
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• 2020

본 논문에서는 전자기 주기구조인 주파수 선택 구조를 레이돔에 적용하는 과정에서 발생하는 결함요소를 해석하기 위해 반-무한배열구조 해석방법을 제안하였다. 3D 전자기 해석 소프트웨어를 이용하여 N×N 유한배열 구조를 해석 하게 되면 많은 해석시간과 메모리가 소요되는 반면 제안한 반-무한배열구조 해석을 이용하면 적은 계산시간으로 전자기성능을 비교적 정확하게 예측할 수 있다. 주기구조해석과 반-무한배열구조의 해석 결과를 비교하여 ±3% 이내의 오차를 확인하였다. 주기적으로 배열된 패턴의 중심부에 발생한 결함요소에 대해 해석과 측정결과를 비교하였으며, 일부 해석과 측정결과의 오차는 존재하지만, 성능변화 지점에서 동일한 경향성과 관심대역에서 유사한 성능저하를 확인하였으며, 반-무한배열구조 해석을 이용하여 전자기 주기구조 내 발생하는 결함요소의 해석 가능성을 확인하였다.

• 대한기계학회논문집
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• 제14권2호
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• pp.422-429
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• 1990

The experimental study investigates two aspects of counterflow sensible heat regenerator operation. First, it examines the regenerator performance in periodic steady state operation with spatially nonuniform inlet temperature in one of the fluid stream. Second, the study examines the transient response of a regenerator to a step change in the inlet temperature of one of the fluid streams. The effect of transient inlet temperatures is analyzed in terms of the response of the outlet fluid temperatures to a step change in temperature of one of the inlet fluid streams. The effect of temperature nonuniformities is analyzed in terms of the change of temperature nonuniformities is analyzed in terms of the change in steady state effectiveness due to a circumferential temperature distribution in one of the inlet fluid streams. an experimental analysis has been conducted using a counterflow, parallel passage, and rotary regenerator made from polyethylene film. Efficiencies follow similar trends with increasing matrix to fluid capacity rate ratio for the balanced and symmetric regenerator with nonuniform inlet temperature.

• 수면정신생리
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• 제25권2호
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• pp.51-57
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• 2018

목 적 : 주기성 사지운동(periodic limb movement syndrome, PLMS)은 수면 중 팔다리를 비롯한 신체 일부가 불수의적이고 주기적으로 움직이는 현상을 말한다. 여러 연구에 의하면 PLMS는 고혈압의 위험인자로 잘 알려져 있고 각각의 PLMS 이후의 혈압이 20 mm Hg까지 증가한다는 연구도 있다. 본 연구에서는 PLMS가 수면 전후 혈압의 변화에 미치는 영향을 알아보고자 하였다. 방 법 : 야간 수면다원검사상 수면무호흡증이 없고(respiratory distress index < 5), 렘수면행동장애, 기면병 등의 수면장애가 없는 358명(남자 176명, 여자 182명)의 18세 이상 성인을 대상으로 하였다. 이들의 수면다원검사 기록과 수면다원검사 전 저녁 수축기, 이완기 혈압, 수면다원검사 후 아침 수축기, 이완기 혈압, body mass index, 음주, 흡연, 혈압강하제 복용 유무, 벡우울척도(Beck Depression Index), 엡워스졸음척도(Epworth Sleepiness Scale), 피츠버그수면질지수(Pittsburgh Sleep Quality Index)를 포함하는 임상 기록들을 수집하였다. 주기성 사지운동지수(Periodic Leg Movement Index) 15를 기준으로 15 이하인 군과 15 초과인 군으로 나누어 비교하였다. 두 군의 임상적 변수 비교는 t-test와 카이제곱 검정을 사용하였으며 repeated measure ANOVA를 사용하여 각 군에서의 검사 전후 혈압 변화 및 두 군의 혈압 변화 양상을 비교하였다. 결 과 : 대상자 전체에서 PLMS가 시간당 15초과한 군이 PLMS 15이하인 군에 비하여 수면 전후 수축기 혈압이 덜 감소하였다. 이러한 결과는 성별과 연령을 보정하였을 때에도 유의하게 나타났으나 BMI, 음주, 흡연, 혈압강하제 사용, sleep efficiency 변수들을 보정하였을 때에는 통계적으로 유의하지 않았다(0.098). 여성에서 두 군간 연령 이외의 다른 변수들은 유의한 차이를 보이지 않았다($49.0{\pm}14.6$세, $57.1{\pm}14.8$세, p = 0.001). 여성의 경우, 두 군 모두 검사 전, 후 수축기 혈압은 유의한 감소를 보였다(p < 0.001). PLMI 15 이하군의 수축기 혈압이 9.7 mm Hg 감소한 것에 비해 PLMI 15 초과군의 수축기 혈압은 2.9 mm Hg 정도만이 감소하여 수면 전, 후 수축기 혈압 변화 양상이 유의하게 차이가 났다($135.2{\pm}20.3mm\;Hg{\rightarrow}125.5{\pm}18.3mm\;Hg$, $133.5{\pm}17.9mm\;Hg{\rightarrow}130.6{\pm}14.8mm\;Hg$, p = 0.010) 이러한 결과는 연령, BMI, 음주, 흡연, 혈압강하제 복용 유무, sleep efficiency 변수를 보정하여도 유의하게 나타났다(p = 0.024). 남성의 경우 두 군 모두에서 수축기 혈압이 수면 전, 후 유의하게 감소하였지만 PLMS에 의한 교호작용(interaction effect)은 나타나지 않았다. 결 론 : PLMS는 수면 중의 정상 혈압 강하 패턴의 감소와 유의한 연관성이 있었으며 혈압과 관련된 임상 변수를 보정하였을 때에는 여성에서만 유의한 연관성을 보였다. 여성에서 PLMS와 관련하여 발생할 수 있는 고혈압 및 심혈관 질환의 임상적 의미를 확인할 수 있었다.

• 대한임베디드공학회논문지
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• 제5권4호
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• pp.206-216
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• 2010

Wireless sensor networks (WSNs) are used to collect various data in environment monitoring applications. A spatial clustering may reduce energy consumption of data collection by partitioning the WSN into a set of spatial clusters with similar sensing data. For each cluster, only a few sensor nodes (samplers) report their sensing data to a base station (BS). The BS may predict the missed data of non-samplers using the spatial correlations between sensor nodes. ASAP is a representative data collection algorithm using the spatial clustering. It periodically reconstructs the entire network into new clusters to accommodate to the change of spatial correlations, which results in high message overhead. In this paper, we propose a new data collection algorithm, name EPDC (Energy-efficient Periodic Data Collection). Unlike ASAP, EPDC identifies a specific cluster consisting of many dissimilar sensor nodes. Then it reconstructs only the cluster into subclusters each of which includes strongly correlated sensor nodes. EPDC also tries to reduce the message overhead by incorporating a judicious probabilistic model transfer method. We evaluate the performance of EPDC and ASAP using a simulation model. The experiment results show that the performance improvement of EPDC is up to 84% compared to ASAP.

• Journal of the Korean Data and Information Science Society
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• 제20권1호
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• pp.89-96
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• 2009

이 논문에서 우리는 1961년부터 2008년 사이의 서울지역 온도변화를 스펙트럴 이분산성 모델을 이용하여 연구하였다. 제안한 모델에서 평균 함수는 계절효과를 주기함수를 이용하여 설명하였고, 온도의 전체적인 상승을 이차 회귀 스플라인 곡선을 이용하여 설명하였다. 분산함수 또한 분산의 계절성을 설명하기 위하여 주기함수를 사용하였다. 우리는 연평균온도가 과거 48년 동안 약 1.5도 가량 증가했음을 알 수 있었다. 연평균온도의 상승은 겨울 온도가 상승하는 것에 기인하는 것이었고, 이는 연중 온도변화의 진폭이 줄어들게 만들었다.

• 한국전기전자재료학회논문지
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• 제20권8호
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• pp.726-730
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• 2007

Two dimensional photonic crystals (2D PCs) have been fabricated by a double exposure holographic method using a He-Cd laser with a wavelength of 442nm. The arrays of the 2D PCs exhibit variable lattice structures from square to triangle according to a change of rotating angle $({\gamma})$ for double exposure beams. In addition, the period and filling factor of PCs as well as the forms (dot or antidot) could be controlled by experimental conditions. $A l.18-{\mu}m-thick$ resist was spin-coated on Si substrate and the 1st holographic exposure was carried out at incident angle $({\theta})$ of $11^{\circ}$. Then the sample was rotated to ${\gamma}=45^{\circ}{\sim}90^{\circ}$ and the 2nd holographic process was performed at ${\theta}=11^{\circ}$. The variation of diffraction efficiency during the exposure process was observed using a He-Ne laser in real time. The images of 2D PCs prepared were analyzed by SEM and AFM. We believe that the double holographic method is a tool suitable to realize the 2D PCs with a periodic array of large area.