• 한국환경과학회지
• /
• 제25권7호
• /
• pp.1007-1016
• /
• 2016

Environmental policy implementation has been strengthened to protect the source waters in Korea and to improve their water quality. Increasing of non-point source caused water quality problem continuously. Research on runoff from forests, which occupy over 65% of the land in korea, is insufficient, and studies on the characteristics and influences of storm runoff are necessary. In this study, we chose to compare the effects of land use in the form of two types of forest distribution and then gathered data on storm characteristics and runoff properties during rainfall events in these areas. Furthermore, the significance and influences of the discharges were analyzed through correlation analysis, and multilateral runoff characteristics were examined by deducing a formula through $COD_{Mn}$ and TOC regression analysis. At two forest points, for which the basin areas differed from each other, flow changed according to storm quantity and intensity. The peak discharge at point A, where the basin area was big, was high, whereas water-quality fundamental items (BOD, $COD_{Mn}$, and SS) and TOC density were high at point B where the slope and storm intensity were high. Effects of dissolved organic matter were determined through correlation analysis, and the regression formulas for $COD_{Mn}$ and TOC were deduced by regression analysis. It is expected that the data from this study could be useful as basic information in establishing forest management measures.

• 동아시아식생활학회지
• /
• 제19권4호
• /
• pp.493-502
• /
• 2009

This study aimed to examine the relationship between nutrient intake and attention deficit hyperactivity (ADH) of children suffering atopic dermatitis. We examined clinical symptoms as well as the status of ADH and the dietary intake of 47 children with atopic dermatitis aged between 4 and 6 against 84 children in the control group. Family history of the atopic dermatitis group was significantly higher than the control group. There was no significant difference between the diet habit of the two groups. The daily energy intake of the atopic dermatitis group and the control group were 1,189.7 kcal and 1245.0 kcal, respectively. There was no significant difference between the nutrient intake of the two groups. In regards to the clinical symptom items, the point for 'anxieties' was 0.5 in the atopic dermatitis group, which was significantly higher than 0.3 of the control group (p<0.05). In terms of the detailed items in ADH assessed by kindergarten teachers, the point for 'changeable feeling' was 0.8 in the atopic dermatitis group, which was significantly higher than 0.5 of the control group (p<0.05). As for the correlation among nutrient intake, the ADH score and clinical symptoms, total fat intake (p<0.05) and animal fat intake (p<0.05) showed a significantly negative correlation with the point of ADH assessed by the teachers, while the intake of fiber (p<0.05) displayed a significantly negative correlation with the point of ADH assessed by the parents. Since atopic dermatitis and ADH may be caused by the same dietary factors, it will be necessary to conduct more studies in this field in the future. In addition, appropriate nutrition management will be necessary for children in the growing period who suffer from atopic dermatitis.

• 대한기계학회논문집B
• /
• 제23권6호
• /
• pp.753-760
• /
• 1999

Experiments were conducted to investigate the effect of the initial turbulent intensity on the flow and heat transfer characteristics for a two-dimensional impinging jet. A square rod was installed at the nozzle exit to increase initial turbulent intensity. A hot wire probe and thermochromic liquid crystal technique were used to measure the turbulent intensity and the surface temperature. All measurements were made over a range of nozzle-to-plate distance from 1 to 10 at Re=20,000. When the rod is not installed, the maximum stagnation point Nusselt number is occurred at H/B=9. A higher initial turbulent intensity enhanced the heat transfer on the surface. A correlation between stagnation point Nusselt number and turbulent intensity are presented.

• 한국전자파학회논문지
• /
• 제21권9호
• /
• pp.995-1004
• /
• 2010

채널의 상태가 변하는 전송 환경에서 수신된 신호에 대한 잡음비를 추정하여, 보다 효율적으로 신호를 전송하는 것은 현대 통신 시스템에서 중요한 기술이다. 기존 NDA(Non-Data-Aided) SNR 추정 방법은 M진 APSK 또는 같은 고차원 신호의 SNR 추정 성능이 떨어진다. 본 논문에서는 OFDM 시스템에서 블록 단위 수신 신호의 영점 자기 상관과 decision feedback 신호의 자기 상관 및 상호 상관을 이용하는 SNR 추정 방법을 제안한다. 본 논문에서 제안한 방법은 decision feedback 신호의 2차 모멘트인 영점 자기 상관을 이용하여 SNR을 추정하는 Type 1 방식과 4차 모멘트 성질을 갖고 있는 영점 자기 상관과 상호 상관을 이용한 Type 2 방식이다. 이 두가지 SNR 추정 방식은 OFDM 시스템에서 블록 단위 수신을 할 때, 신호의 상관 관계에 기반을 두고 있어 SNR 추정 방법의 실용적인 구현이 가능하게 하고, decision feedback 신호를 사용함으로써 QAM 신호에서도 종전의 SNR 추정 방식들보다 비교적 안정적인 추정 성능을 보인다. 또한, decision feedback 신호를 사용할 때 자기 상관과 상호 상관의 오차에 따른 SNR 추정 식을 수식적으로 유도한다. 그리고 Monte Carlo 시뮬레이션을 통해 제안한 SNR 추정 방법의 성능을 확인한다.

• 한국해양환경ㆍ에너지학회지
• /
• 제5권3호
• /
• pp.10-15
• /
• 2002

반복적으로 나타나는 고정된 이차원 모래언덕에 의하여 생성되는 난류유동장을 해석하기 위하여 PIV 기법을 적용하였다. PIV 기법의 사정을 위하여 LDV 실험자료와 결과를 비교하였는데 유동박리 및 큰 전단유동 영역에까지 좋은 결과를 보여주었다 레이저 시트로 조사된 이차원 단면의 흐름을 이미징 테크닉으로 해석하는 PIV 방법이 갖는 고유의 단점들을 완전히 해결하지는 못하였으나, 전체적으로 LDV 결과와 매우 잘 일치하고 있었으며 특히 Two-point correlation 이나 Quadrant analysis와 같이 고차항까지를 추적할 수 있었다 특히 기존의 일점계측법으로는 해석이 불가능한 순간유동장의 가시화 및 정량화가 가능하였으며 Time-series로 변환시킨 PIV 데이터의 신뢰성도 확인이 가능하였다. 추후 토사이동과 같은 복잡한 유동해석에도 본 기법을 그대로 활용할 수 있으리라 기대한다.

• The Journal of Korean Physical Therapy
• /
• 제22권1호
• /
• pp.83-90
• /
• 2010

Purpose: This study aimed to determine the degree of job stress and self-esteem of physical therapists as well as the correlation between the two variables. Method: This study targeted 218 physical therapists of Busan City, and was carried out from July 16 to August 6, 2009 as survey research. A structured questionnaire referring to advance researches was used as a research tool. Job stress symptoms were measured one a 5 point scale, the higher the point total, the higher the job stress. Self-esteem was measured on a 4 point scale, the higher the point total, the lower the self-esteem. After data collection we determined descriptive statistics, and did reliability analysis, factor analysis, Spearman's correlation analysis, and regression analysis. Results: Reliability analysis indicated that reliability for the job stress questionnaire was 0.93 and for the self-esteem was 0.83. The average job stress score of physical therapists was 1.19 points which was not high. The average self-esteem score was 1.76 points, whichwas high. It appeared that the higher the self-esteem, the lower the job stress. Also, self-esteem had an influence on psychological symptoms among job stress factors. Conclusion: Job stress and self-esteem of physical therapists are well-correlated and influence each other. Accordingly, self-esteem can be used as a variable for adjusting job stress of physical therapists.

• 천문학회지
• /
• 제31권2호
• /
• pp.105-108
• /
• 1998

We have found that the two-point correlation function of the APM clusters of galaxies has an amplitude much higher than that claimed by the APM group. As the richness limit increases from R = 53 to 80, the correlation length increases from 17.5 to 28.9 $h^{-1}Mpc$. This indicates that the richness dependence of the APM cluster correlation function is also much stronger than what the APM group has reported. The richness dependence can be represented by a fitting formula ro = 0.53dc + 0.01, which is consistent with the Bahcall's formula ro = 0.4dc. We have tried to find the possible reason for discrepancies. However, our estimates for the APM cluster correlation function are found to be robust against variation of the method of calculation and of sample definition.

• 천문학논총
• /
• 제27권4호
• /
• pp.343-344
• /
• 2012

We present the first measurement of the angular two-point correlation function for AKARI $90{\mu}m$ point sources, detected outside of the Milky Way plane and selected as candidates for extragalactic sources. This is the first measurement of the large-scale angular clustering of galaxies selected in the far-infrared after IRAS. We find a positive clustering signal in both hemispheres extending up to ~ 40 degrees, without any significant fluctuations at larger scales. The observed correlation function is well fitted by a power law function. However, southern galaxies seem to be more strongly clustered than northern ones and the difference is statistically significant. The reason for this difference - technical or physical - is still to be found.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2003년도 추계 학술대회논문집
• /
• pp.158-163
• /
• 2003

This paper assesses the two-equation turbulence models available in a commercial code, FLUENT, for heat transfer in a turbulent heated pipe flow. In case of flow under $Re_D=10,000$, Standard $\kappa-\epsilon$ and Realizable $\kappa-\epsilon$ models overpredict the Nusselt number about $20\%$ compared with the experimental correlation, and RNG $\kappa-\epsilon$ model overpredicts about $30\%$ when the two-layer zonal method is employed. When wall function method is adopted, all $\kappa-\epsilon$ models show better predictions. Standard $\kappa-\omega$ and SST $\kappa-\omega$ models have the dependency on the first grid point ($0.3). As Reynolds number becomes high, the predictions of all $\kappa-\epsilon$ and $\kappa-\omega$ models are in a good agreement with the experimental correlation.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2006년도 하계종합학술대회
• /
• pp.319-320
• /
• 2006

In this paper, we propose a vision based system employing two cameras to provide effective touch screen function. The two main processes - determining touch (or no-touch) and contact location of screen plane - are essential for enabling touch screen function. First region of interest is found by using color characteristic and histogram for determining the contact mode. Second, if the hand touches the mirror, the fingertip point in image is found using the correlation coefficient based on the mirror attribute. Subsequently, the fingertip coordinate in image is transformed to the location in mirror plane by using four predefined points (termed as four-point method) and bilinear transform. Representative experimental results show that the proposed system is suited to touch screen.