• 한국지반환경공학회 논문집
• /
• 제16권2호
• /
• pp.15-25
• /
• 2015

경량기포혼합토는 운반 과정에서 재료의 물성이 변화하므로, 시공 시의 성질이 설계 품질을 만족하는지를 확인할 필요가 있다. 본 연구는 현장시험을 통해 믹스트럭 운반에 의한 재료특성의 변화를 분석하는데 목적이 있다. 현장시험에 사용된 경량기포혼합토는 단위중량 $9.0{\pm}1.0kN/m^3$, 흐름값 $190{\pm}20mm$로 제작되었다. 재료특성의 변화를 분석하고자 운반 전 후 시료의 단위중량과 흐름값을 측정하고, 일축압축강도 시험을 실시하였다. 교반시간은 19~175분으로 다양화하였다. 시험결과 경량기포혼합토는 교반에 의해 단위중량, 흐름값과 일축압축강도는 변화하나 품질관리기준은 만족하였다. 운반 후 단위중량과 흐름값의 평균 변화량은 $(+)0.10kN/m^3$, 4.8mm로 교반시간에 따른 단위중량과 흐름값의 평균변화량은 일정하였다. 28일 일축압축강도는 $20{\sim}150kN/m^2$ 증가하나 변화량과 교반시간과의 관계는 명확하지 않았다. 결론적으로 175분 이내에서의 운반에 의한 물성의 변화는 적으므로 적용에 문제는 발생하지 않을 것으로 생각된다.

• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2006년도 하계학술발표대회 논문집
• /
• pp.1043-1048
• /
• 2006

This paper aimed to verify and develop lighting design data for offices in Korea. It focused on a Korean standard office value relative to lighting density and the evaluation of lighting energy and cooling load. When planning indoor lighting design, we generally utilize the lighting density value which is set $14W/m^2$ by the ASHRAE/IES standard office value. However, the value is not appropriate to apply in Korea where higher efficiency lamps are more popular than others. For calculation of a proper lighting density of Korea, we analysed distribution curves of luminous intensity(2-lamp fluorescent lighting fixture with Parabolic) and derived the new lighting density $12.64W/m^2$ as Korea standard office value. In the simulation using this value, it was shown that lighting energy and cooling load could be reduced.

• 대한방사성의약품학회지
• /
• 제3권1호
• /
• pp.18-24
• /
• 2017

Patient-specific image-based internal dosimetry involves using the patient's individual anatomy and spatial distribution of radioactivity over time to obtain an absorbed dose calculation. Individual absorbed dose was calculated by accumulated activity multiply S-value of each organs. The aim of this study was to calculate the S-values using Monte Carlo simulation in monkey and mouse and evaluation of absorbed dose in each organ. Self-irradiation S-value of monkey heart self-irradiation was 3.15E-03 mGy-g/MBq-s, lung self-irradiation was 8.94E-04 mGy-g/MBq-s and liver self-irradiation S-value was 2.23E-03 mGy-g/MBq-s. Mouse heart self-irradiation S-value was 1.95E-01 mGy-g/MBq-s, lung was 9.59E-02 mGy-g/MBq-s, and liver was 1.40E-03 mGy-g/MBq-s. The results of this study show that the calculation protocol of image based individual absorbed dose of each organ using Monte Carlo simulation. Therefore, this study may be applied to calculate human specific absorbed dose.

• 한국지구과학회지
• /
• 제28권7호
• /
• pp.825-837
• /
• 2007

한국 국립해양조사원의 수심자료와 미국 NIMA((National Imagery and Happing Agency)의 수치지형자료를 바탕으로 우리나라 일원에서 측정한 중력의 지형보정을 위한 위도 및 경도 간격이 각각 $3"{\times}3"$)인 지형자료를 재편집하였다. 이 자료를 바탕으로 지구 곡률을 고려한 정밀 지형보정값을 계산하기 위한 알고리즘을 개발하였고, 중력측정점으로부터 반지름 166.735 km인 원 내부에 대한 지형보정값을 계산하는 Fortran프로그램을 작성하였다. 이 알고리즘 및 프로그램을 이용하여 남한 전역에 대한 지형보정값을 계산하였다. 그 결과 최대값은 56.508 mGal 이고 평균값은 4.539 mGU이다.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2007년도 춘계학술대회
• /
• pp.456-459
• /
• 2007

Thermal conductivities (TC) of 57 Jurassic muscovitic granite samples (KIGAM) and 149 porphyritic granite samples (Yeonki: BE-2, BE-3) were measured with LFA-447. Ranges of TC values are $2.429{\sim}3.878$ W/mK (KIGAM), $2.220{\sim}3.767$ W/mK (Yeonki, BE-2) and $2.019{\sim}3.990$ W/mK (Yeonki, BE-3); arithmetic means are 2.924 W/mK (KIGAM), 2.907 W/mK (Yeonki, BE-2), and 2.881 W/mK (Yeonki, BE-3), respectively. In this study, harmonic mean values were calculated to estimate the average value of TC. Harmonic mean values are 2.883 W/mK (KIGAM), 2.886 W/mK (Yeonki, BE-2), and 2.866 W/mK (Yeonki, BE-3), respectively. Heat extraction rates of a borehole heat exchanger strongly depend on TC values. Heat-extraction rates from re values are expected to be a little lower than 84 W/m in all sites. However, considering ground water flow, it is expected that actual heat extraction rate would be higher than the expected value.

• 대한수학회보
• /
• 제41권3호
• /
• pp.483-492
• /
• 2004

Let : [0, 1] $\times$ [0, $\infty$) $\longrightarrow$ [0, $\infty$) be continuous and a ${\in}$ C([0, 1], [0, $\infty$)),and let ${\xi}_{i}$ $\in$ (0, 1) with 0 < {\xi}$_1$ < ${\xi}_2$ < … < ${\xi}_{m-2}$ < 1, $a_{i}$, $b_{i}$ ${\in}$ [0, $\infty$) with 0 < $\Sigma_{i=1}$ /$^{m-2}$ $a_{i}$ < 1 and $\Sigma_{i=1}$$^{m-2}$ < l. This paper is concerned with the following m-point boundary value problem: $\chi$″(t)＋a(t) (t.$\chi$(t))＝0,t ${\in}$(0,1), $\chi$'(0)＝$\Sigma_{i=1}$ $^{m-2}$ /$b_{i}$$\chi$'(${\xi}_{i}$),$\chi$(1)＝$\Sigma_{i=1}$$^{m-2}$$a_{i}$$\chi$(${\xi}_{i}$). The existence, multiplicity and uniqueness of positive solutions of this problem are discussed with the help of two fixed point theorems in cones, respectively.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
• /
• pp.596-599
• /
• 2004

The purpose of this study is to investigate properties of porous concrete according to rheological properties of binder and compaction factor. The results of this study, the rheological property of binder is stabilized when a mixing time is over 240 seconds in case of target flow values are $175\%\;and\;200\%$. The void ratio of specimen has a very near value by target void ratio on the whole according as the rheological properties of binder and compaction energy are changed when target flow value is $200\%$, compaction energy is $75kN{\cdot}m/m^2$. The specimen has the excellent compressive strength when compaction energy and target flow value are $100kN{\cdot}m/m^2$ and $200\%$ respectively.

• Journal of applied mathematics & informatics
• /
• 제35권5_6호
• /
• pp.551-563
• /
• 2017

In this paper, by using fixed point theorems in cones, the existence of positive solutions is considered for nonlinear m-point boundary value problem for the following second-order dynamic equations on time scales $$u^{{\Delta}{\nabla}}(t)+a(t)f(t,u(t))=0,\;t{\in}(0,T),\;{\beta}u(0)-{\gamma}u^{\Delta}(0)=0,\;u(T)={\sum_{i=1}^{m-2}}\;a_iu({\xi}_i),\;m{\geq}3$$, where $a(t){\in}C_{ld}((0,T),\;[0,+{\infty}))$, $f{\in}C([0,T]{\times}[0,+{\infty}),\;(-{\infty},+{\infty}))$, the nonlinear term f is allowed to change sign. We obtain several existence theorems of positive solutions for the above boundary value problems. In particular, our criteria generalize and improve some known results [15] and the obtained conditions are different from related literature [14]. As an application, an example to demonstrate our results is given.

• 대한수학회지
• /
• 제43권6호
• /
• pp.1199-1217
• /
• 2006

The main purpose of this paper is using the properties of Gauss sums, primitive characters and the mean value theorems of Dirichlet L-functions to study the hybrid mean value of the T-th hyper-Kloosterman sums Kl(h, k+1, r;q) and the hyper Cochrane sums C(h, q; m, k), and give an interesting mean value formula.

• 자원환경지질
• /
• 제21권3호
• /
• pp.277-285
• /
• 1988

The ELF-MT survey has been conducted at 9 points along the national road between the Sindangri and Dojonri area to study on the boundary between the Okchon and Choson systems, and subsurface geological structure of these two systems. Natural electromagnetic fields of 7.8, 14, and 20 Hz in the Schumann resonant frequency band were used for ELF-MT measurement. Apparent resistivity values were calculated from the measured magnetic and electric fields at each frequency, and resistivity sections were obtained by means of a trial and error method for one-dimensional analysis and finite element method for two-dimensioal analysis. The results of this study show that the resistivities of the Okchon and Choson systems are 700-3500 ohm-m and 40-5000 ohm-m, respectively. The boundary between these two systems is a fault with the width of 1 km fault zone and resistivity value of 200 ohm-m, and is located around Koburangjae. Another fault is appeared in Sindangri, and its resistivity value is 130 ohm-m. Intrusion of biotite granite is distributed in Jungchijae, and its resistivity value is 750 ohm-m. The area between Susanri and Koburangjae shows the highest resistivity value of 3500 ohm-m because metabasite and amphibolite are distributed in that area. Extremely low resistivity value of 40 ohm-m around Yongamsan is due to the Yongam formation, which is composed of graphitic black slate and overlying Choson Great Limestone group.