• 천문학회보
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• 제19권
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• pp.9.2-10
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• 1994

• 한국지반공학회논문집
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• 제20권9호
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• pp.105-114
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• 2004

액성한계 두 배 이상의 매우 높은 함수비를 갖는 준설점토의 압밀특성을 파악하기 위해 Rowe cell 압밀시험기를 사용하여 압밀시험을 실시하였다. 초기함수비 변화가 압밀특성에 주는 영향을 검토하기 위해서 함수비를 $100\~150\%로$ 변화시켜서 실험을 수행하였고 재성형 준설점토의 압밀특성과 비교하였다. 실험결과로부터 준설점토의 초기함수비가 증가할수록 e-logP 곡선의 비선형적 거동이 뚜렷하였고, 하중단계 40kPa까지는 곡선의 기울기 변화가 급변하였으며 그 이후의 하중단계에서는 완만한 형상을 보여주었다. 압축지수비는 Mesri(1973)가 제안한 값의 범위 내에 존재하였으며, 초기함수비변화가 압밀계수에 미치는 영향은 거의 없었고 오히려 압밀하중의 크기가 연직압밀계수에 영향을 미치고 있음을 알 수 있었다. 또한 대형압밀시험기를 이용하여 압밀기간 중 층 두께의 변화를 고려하여 압밀기간을 산정하는 Mikasa이론과 그렇지 않은 Terzaghi의 이론을 비교하였다. 그 결과 변형률이 큰 지반에서의 압밀기간은 압밀기간 중 층 두께의 변화를 고려한 Mikasa 이론의 경우가 그렇지 않은 경우보다 실측치에 근사하게 산정되었다.

• 펄프종이기술
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• 제41권5호
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• pp.50-58
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• 2009

Periodic variation of local paper structure was evaluated using two-dimensional fast Fourier transform (FFT) and spectral analysis. Since the periodic variation could originate from various sources and have different magnitudes and patterns depending on the origins, a complete analysis of local paper structure properties such as local grammage, local thickness, local apparent density and surface topography was proposed in this study. For a commercial copy paper, the individual periodic patterns for each local structural property were identified by using inverse FFT spectrums of the filtered spectrum. The spectral analysis of newsprint sample provided the period of variation quantitatively, which was useful in comparing the origins of the individual periodic patterns of the local structural properties.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.2071-2075
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• 2003

Pressure variation is one of the major sources on noise emission in the oil hydraulic piston pumps. Therefore, it is necessary to clarify about pressure variation characteristics of the oil hydraulic piston pumps to reduce noise. Pressure variations in a cylinder at trapping region were measured during pump working period with discharge pressures, rotational speeds. The effect of pre-compression of the discharge port with three types valve plates also investigated. It was found that the pressure variation characteristics of oil hydraulic piston pumps deeply related with pre-compression design of the discharge port. Also, it was found that the pressure overshoot at trapping region can reduce by use of pre-compression at the end of the discharge port in valve plate

• Journal of Astronomy and Space Sciences
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• 제15권1호
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• pp.69-74
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• 1998

Two colour(B & V) photoelectric observations of EB-type eclipsing binary GO Cyg were carried out for 15 nights during October and December 1996. Three new times of minimum derived from our own observations are presented. With these and previously published times, the period variation is studied, and a continuous period increase of $dP/dt{\approx}1.51{\times}10^{-7}d/yr$ is estimated from the quadratic ephemeris.

• 한국대기환경학회지
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• 제30권2호
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• pp.128-138
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• 2014

This study has analyzed the concentration variation of four air pollutants ($PM_{10}$, $NO_2$, CO, and $SO_2$) during the typhoon periods over 10 years (2002~2011). In this study, 10 typhoon events which had rainfalls in Korean Peninsula were selected during the study period. The analysis was performed using the observation data of both the air pollutants and rainfall. In order to examine and compare the concentrations of the air pollutants between normal periods and typhoon periods, we have obtained monthly average concentrations from July to September and daily average concentrations during typhoon periods. For the period from July to September, 34% of the total rainfalls can be explained by typhoons, and the concentration of air pollutants during the typhoon period was lower than the normal period. In addition, the concentration variations of the pollutants during the typhoon period were analyzed according to two categories: differences in the concentrations between the day before and the day of the typhoon (Case 1) and between the day before and after the typhoon (Case 2). The results indicated that the reduction rate of $PM_{10}$, $NO_2$, CO, and $SO_2$ was 30.1%, 17.9%, 11.6%, 9.7% (Case 1) and 22.8%, 21.0%, 9.0%, 8.0% (Case 2), respectively. This result suggested that air quality was significantly improved during the typhoon period than after the typhoon period by the rainfall.

• 헤리티지:역사와 과학
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• 제41권1호
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• pp.21-33
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• 2008

충청지역의 다양한 유적의 소토(燒土)에서 구한 34점의 고고지자기 측정데이터를 통해 충청지역의 고고지자기 변동 양상을 살펴보고, 더 나아가 국내에서의 지자기의 지역적인 차이에 대해 검토해 보았다. 충청지역의 고고지자기 측정데이터는 거리상으로 차이가 있는 일본의 고고지자기 변동과의 비교에서 보면, 전체적인 변동 모습은 비슷하나 A.D. 300년경에서는 편각이 동쪽으로 10도 이상 치우치는 현저한 차이를 보이고, 그 이외 시기에서는 복각이 다소 깊어지고 편각이 서쪽으로 약간씩 치우치는 지자기의 지역적인 차이가 확인되었다. 이러한 양상은 우리나라 전체의 고고지자기 변동 양상과 큰 차이가 없으며, 충청지역 데이터와의 직접 비교에서도 국내에서는 서력기원전시기와 기원후 시기 모두 뚜렷한 지자기의 지역차는 확인되지 않았다. 앞으로 더 많은 고고지자기 측정 데이터가 증가하고 다양한 시기의 데이터가 채워지면 더욱 명확해 지겠지만, 충청지역 유적의 고고지자기 측정결과를 통해 볼 때, 지자기의 지역적인 차이에 의해 발생하는 고고지자기 측정연대의 오차와 같은 문제점은 우리나라 내에서는 크게 걱정하지 않아도 될 듯하다. 게다가 시료의 채취와 측정에서 신뢰가 가능한 측정데이터를 구하기 위하여 많은 노력들을 하고 있기 때문에, 고고지자기 측정결과에서 추정연대의 오차문제 뿐만 아니라 데이터의 신뢰도의 측면에서도 문제가 없을 것이라 생각된다.

• 콘크리트학회논문집
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• 제17권2호
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• pp.237-245
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• 2005

본 연구에서는 우리나라 기상청의 기온자료를 이용하여 시간변화에 따른 각 지역의 한중콘크리트 적용기간을 KCI, ACI 및 AIJ 방법에 따라 산정한 후 동방법의 기존연구결과와 비교 분석함으로써 시간변화에 따른 한중콘크리트 적용기간의 변화를 분석하고자 하였다. 연구결과에 따르면, KCI에 의한 적용기간은 평균 9.5순으로 나타났고, ACI에 의한 적용기간은 10.1순 그리고 AIJ에 의한 적용기간은 9.2순으로 산정되었다. 시간변화에 따른 적용기간으로서 KCI 및 ACI 규정에 의한 본연구의 적용기간은 10년전의 종전 연구보다 약 5${\~}$6일 정도 짧아진 것으로 확인되었으나, AIJ 규정에 의한 적용기간은 종전의 연구와 거의 차이가 없었고, 단, 김의 연구와 비교할 경우 약 3일 정도 짧아지는 것으로 나타났다. 한편, 지역별로는 남부지방의 경우 종전연구에 비하여 한중콘크리트 적용기간이 비교적 많이 단축되었는데,. 이는 지구의 온난화에 의한 평균기온의 상승으로 인한 것으로 사료된다.

• 한국대기환경학회지
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• 제5권1호
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• pp.11-21
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• 1989

Atmospheric gaseous mercury was automatically measured by a mercury air monitor (Mercury monitor AM-1). The sample air was led to a scrubber and washed with buffer solution, and mercury was trapped with gold coated chromosorb P(AW) was successively eluted by heating the chromosorb and then detected by the cold vapor atomic absorption spectrophotometry. $SO_2, TSP, NO_x, CO, THC$. and some of meteorological factors were also measured simultaneously with mercury. A significant correlation between the concentration of mercury and those of 2,513 measurements, gaseous mercury concentration ranged from 4.73 to 112.8 $ng/m^3$ with an annual mean of 14.7$ng/m^3$ in urban area. At this place there was a clear seasonal variation with a maximuminDecember-January and aminimum in March-June. A secondary maximum existed in August to September. THe seasonal variation was found that the gaseous mercury in ambient air has a tendency to become low in spring and high in winter. Namely, the average of concentration in winter was about two times, 19.2 $ng/m^3$, higher than that in spring. In Seoul mercury levels on some months mainly Septermber-October increase with increasing relative humidity of the atmosphere. In Olympic park air levels were 8.2 (range 4.4-23.7)$ng/m^3$ with an coefficients of variation of 0.34 and in Seoul sports complex those were 7.7 (rnage 4.4-25.5) $ng/m^3$ with an coefficients of variation of 0.38 within the Seoul olympiad holding period of time. A significant diurnal mercury variation occurs both at the measuring sites and in the period of observation.

• Asian-Australasian Journal of Animal Sciences
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• 제17권1호
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• pp.94-101
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• 2004

The gross composition, gross amino acid content, apparent ileal amino acid digestibility and apparent ileal digestible amino acid content from 64 commercially produced meat and bone meals were statistically analysed. The samples were produced by 22 plants over a 2.5 year period with eight plants using batch dry rendering and 14 plants using low temperature rendering. A linear model with method and time of year (period) as fixed effects, plant within method as a random effect and sheep percent as a covariate was fitted to the composition data. The majority of the variation in the gross composition, amino acid digestibility and digestible amino acid content was explained by differences between plants using the same method. Neither rendering season nor origin of the raw materials contributed significantly to the observed variation in meat and bone meal protein quality. Rendering method (low temperature or batch rendering) had a significant effect on the variation observed in gross fat content, gross energy content, pepsin nitrogen digestibility, protein solubility and total lanthionine content. The digestibility of a number of amino acids and the apparent digestible content of arginine, cysteine, aspartic acid, proline and hydroxyproline were also significantly affected by rendering method. On average, batch dry and low temperature rendering systems produce meat and bone meals of similar nutritional quality. The variation between plant and within plant, however, is large, indicating that purchasing meat and bone meal from the same plant does not guarantee a consistent quality.