본 연구에서는 관전압과 관전류량이 디지털 방사선영상에서 적용되고 있는 노출 지수에 미치는 영향을 알아보고자 하였다. 방사선발생장치는 인버터방식의 디지털 X선 발생장치를 사용했으며 영상검출체는 포터블 형태의 무선 디텍터를 그리드 없이 사용하였다. 방사선영상은 3D 프린터를 이용하여 제작한 원뿔형 피라미드 팬텀을 이용하여 획득하였다. X선의 관전압 조사조건은 40 kVp부터 120 kVp까지 10 kVp 씩 증가시켰고 각 관전압에서 관전류량은 1 mAs에서부터 128 mAs까지 배수적으로 증가시켰다. 그 결과 관전압이 EI와 높은 R2값으로 로그 함수적 관계가 있었으며 관전류량이 매우 높은 선형적인 관계가 있었다. 또한 영상 검출체의 면적선량과 EI도 R2값이 0.76 이상으로 높은 상관관계가 있었다. 결론적으로 관전류량이 EI에 선형적으로 영향을 주었으며, 적절한 영상품질 유지를 위해서는 예측이 용이한 관전류량을 주로 조절하 는 것이 유리하다고 판단된다.

The pathological condition of excessive melanogenesis causing freckles, melasma, senile lentigo, pigmented acne scars, and cancer has a critical impact on the wellness of individuals. The mechanism of melanogenesis is related to the expression of melanogenic enzymes. Here, we evaluated the inhibitory effect of pine cone (Pinus densiflora) extracts on melanogenesis. P. densiflora, the Korean Red Pine, is the predominant tree species in the cool, temperate forests of northeast Asia, occurring in pure stands across Korea, Japan, and parts of northern China and Russia. P. densiflora leaves, pollen, and bark have been widely used for traditional medicine, or edible purposes. However, pine cones are rarely used as natural raw materials, although they contain many bioactive phytochemicals. The pine cone ethyl acetate fraction (PEF) showed no toxicity to B16F10 cells at a concentration of less than 100 ㎍/mL. PEF inhibited the expression of microphthalmiaassociated transcription factor (MITF), tyrosinase and tyrosinase-related factors in B16F10 cells treated with 3-Isobutyl- 1-methylxanthine (IBMX). These results suggest that pine cones can be used as an effective natural melanogenesis inhibitory agent.

치과 콘빔 전산화단층 검사 시 갑상선 부위의 방사선 피폭선량을 최소화하기 위하여 보루스 (Bolus)를 이용한 차폐체를 제작하고, 방사선 차폐 효과와 영상의 적정성을 평가하였다. 치과용 콘빔 전산화단층검사 장비를 사용하여 치과방사선 두부 팬텀을 대상으로 갑상선의 좌, 우측 부위에 유리선량계를 부착시켜 방사선량을 측정하였다. 차폐체의 두께를 각각 10 mm, 20 mm, 30 mm로 다르게 하여 각 차폐체별로 흡수선량을 측정하여 차폐체를 사용하지 않았을 경우와 비교하였다. 8명의 평가자가 진료영상의 적정성을 여부를 평가하였다. 왼쪽 갑상선 부위에 30 mm Bolus 차폐체를 사용한 경우에는 결과값이 평균 342.67 μ㏉로 Bolu s 차폐체를 사용하지 않고 측정한 결과값의 평균 431.22 μ㏉보다 20.7% 감소하였고, 오른쪽 갑상선 부위에 30 mm Bolus 차폐체를 사용한 경우에는 평균 424.56 μ㏉로 21.9%의 선량감소효과를 보였다. 진료 영상의 적정성은 평가자 모두 사용 가능하다 판단하였다. 결론적으로, 치과 콘빔 전산화단층검사 시 갑상선 부위의 방사선 피폭선량을 최소화하기 위해 제작된 Bolus 차폐체는 장해음영 없이 적정한 진단 영상 처리가 가능하고, 방사선차폐 효과가 있어 유용한 차폐체로 적용 가능할 것으로 사료된다.

The cone beam computed tomography(CBCT) which can acquire 3-dimensions images is widely used for confirmation of patient position before radiation therapy. In this study, through the simulation using the Monte Carlo technique, we will analyze the exposure dose by cone beam computed tomography and present the standardized data. For the experiment, MCNPX(ver. 2.5.0) was used and the photon beam spectrum was analyzed after Cone beam was simulated. As a result of analyzing the photon beam spectrum, the average energy ranged from 25.7 to 37.6 keV at the tube voltage of 80 ∼ 120 kVp and the characteristic X-ray energy was 9, 60, 68 and 70 keV. As a result of using the water phantom, the percentage depth dose was measured, and the maximum dose appeared on the surface and decreased with depth. The absorbed dose also decreased as the depth increased. The absorbed dose of the whole phantom was 9.7 ~ 18.7 mGy. This is a dose which accounts for 0.2% of about 10 Gy, which is generally used for radiation therapy per week, which is not expected to have a significant effect on the treatment effect. However, it should not be overlooked even if it is small compared with prescription dose

This study was conducted to estimate the removal efficiency of algae by a mechanical Screw Brush Cone Filter in a lake. The device used a stainless steel cone-shaped filter with a screw brush. The ability of the developed device to remove algae larger than 20μm in Lake ChaSa, Gwangyang city was tested from August to September 2014. The results show that the removal rates for chlorophyll-a, suspended solids and volatile suspended solids were 44-87%(mean 61%), 35-54%(mean 40%), and 37-46%(mean 43%), respectively. This study also discusses equipment and device operation costs and device application problems, and suggests in situ. solutions to these problems.

Antioxidant activity and inhibitory effect on oxidative DNA damage of ethyl acetate fractions extracted from Cone of Red Pine (Pinus densiflora) were investigated to find utilization of Cone, by-product of Red Pine, thrown out after berry shatter, as a new natural plant resource. Cone from P. densiflora was extracted with methanol (MeOH) and separated to petroleum ether, ethyl acetate and water fraction. Among them, ethyl acetate fraction was used. The antioxidant activity was conducted by the 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical, 2, 2'-Azino-bis (3-ethylbenzothiazoline-6 sulfonic acid) diammonium salt (ABTS) radical scavenging assay, Fe 2+ chelating assay and reducing power assay. The inhibitory effect on oxidative DNA damage was determined by DNA cleavage assay using φX-174 RF I plasmid. The results of DPPH and ABTS radical scavenging activity at 200 ㎍/㎖ of extracts were 86.50% and 95.80% respectively, which were similar figures compared with L-ascorbic acid as control. Fe 2+ chelating activity was 77.96% and reducing power was 0.77 at 200 ㎍/㎖. Total phenolic component was 27.29±0.3 ㎎/g and Vitamin C content was 1.84±0.1 ㎎/g. Also ethyl acetate fraction from Cone has inhibitory effect, using φX-174 RF I plasmid on DNA cleavage assay. In conclusion, Cone, by-product of P. densiflora, showed high antioxidant activity and inhibitory effect on oxidative DNA damage. Therefore this study suggests Cone, useless by-product, can be developed as a new natural plant resource with lots of utilization such as an effective antioxidant, natural medicine, food, cosmetics and so on.

원위치에서 공학적 정수의 산정을 위하여 지반특성에 따라 표준관입실험(SPT), 동적 콘관입실험(DCPT), 정적 콘관입실험(SCPT) 등 다양한 실험방법들이 적용되어 왔다. SPT 및 DCPT의 경우 실험방법이 간단한 반면 결과의 신뢰도는 낮으며, SCPT의 경우 실험결과의 신뢰성은 높으나, 대상현장에 따라 관입장비의 적용에 한계가 있어 왔다. 본 연구에서는 계장화된 동적 콘관입기(Instrumented Dynamic Cone Penetrometer, 이하 IDCP)를 개발하여 CPT의 적용이 어려운 현장의 지반특성을 파악하고자 하였다. IDCP는 원추형 선단부와 연결롯드, 그리고 두부로 구성되어 있으며, 선단부 및 두부에는 변형률계와 가속도계를 설치함으로써, 각 부분에서의 힘, 속도, 변위, 그리고 전달된 에너지를 측정할 수 있도록 하였다. IDCP의 관입을 위한 해머 및 관입장비는 대상현장에 따라 SPT 및 DCPT와 동일한 방식으로 적용되었다. IDCP를 이용한 실내 및 현장적용 실험결과, 동적관입에 따라 측정된 선단의 저항력은 두부로부터 선단으로 전달된 에너지의 손실에 대한 영향없이 대상지반의 강도분포를 우수하게 나타내고 있음을 보여주었다. 본 논문에서 개발된 IDCP는 기존 실험법의 한계점을 보완함으로써, 현장적용성이 우수하고, 정량적인 강도분포의 도출이 가능한 지반조사장비로 활용될 수 있을 것으로 예상된다.

This study developed an indirect measurement method for viscosity and yield-stress using an reduced v-funnel and mini-slump cone and proposed the correlation graph between v-funnel flow time and viscosity, mini-slump flow and yield stress.

This study characterized PM and VOC emissions from cow dung combustion in a controlled experiment. Dung from grass-fed cows was dried and combusted using a dual cone calorimeter. Heat fluxes of 10, 25, and 50 kW/m² were applied. The concentrations of PM and VOCs were determined using a dust spectrometer and gas chromatography/mass spectrometry, respectively. PM and VOC emission factors were much higher for the lower heat flux, implying a fire ignition stage. When the heat flux was 50 kW/m², the CO₂ emission factor was highest and the PM and VOC emission factors were lowest. Particle concentrations were highest in the 0.23-0.3-μm size range at heat fluxes of 25 kW/m² and 50 kW/m². Various toxic VOCs including acetone, methyl ethyl ketone, benzene, and toluene were detected at high concentrations. Although PM and VOC emission factors at 50 kW/m² were lower, they were high enough to cause extremely high indoor air pollution. The characteristics of PM and VOC emissions from cow dung combustion indicated potential health effects of indoor air pollution in developing countries.

A method to measure rheological properties of cementitious materials through mini slump test has been previously suggested. In this study, experiments were performed to verify that method. As the mini slump test proceeds, the spreading diameter of the material were measured by using a digital image processing technique. From the measured spreading diameter versus time curve, the rheological properties were estimated and compared to the properties measured from the viscometer.