• Progress in Medical Physics
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• v.7 no.1
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• pp.79-89
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• 1996

The purpose of this study was to examine the dead time effects and derive the correction factor. Using the thyroid probe and lucite cylindrical phantom, $^{99m}Tc$ 10.50mCi and $^{123}I$ 2.08mCi were counted with medical spectrometer at intervals of 2 hours for 43hrs and 79 hours. respectively. $^{123}I$ 2.06mCi was counted at intervals of 6 hours for 910 hours. To measure the starting point of dead time effect, the radioactivity was measured with dose calibrator in each time. The dead time effects started at about 0.80mCi at all distances for $^{99m}Tc$, and about 1.00mCi for $^{123}I$. The radioactivity corresponding to 20％ counts loss is 1.29(center), 1.28(2cm), 1.31(4cm), 1.13(6cm)mCi for $^{99m}Tc$ and 1.39mCi for $^{123}I$. The correction factors for 2mCi of radioactivity as an example were 1.52(center), 1.52(2cm), 1.50(4cm), 1.58(6cm) for $^{99m}Tc$ and 1.58 for $^{123}I$.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.978-978
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• 2012

최근 들어, 지구온난화에 따른 기후변화로 인해 홍수와 가뭄 등과 같은 자연재해가 과거에 비해 빈번히 발생되고 있으며 그로인한 수많은 인명 및 재산피해가 나타나고 있다. 특히, 가뭄의 경우 홍수 등 여타의 수문학적 재해에 비해 서서히 장기간에 걸쳐 피해를 유발하고 있는데 미국해양기상청(NOAA)에서 선정한 20세기 최대의 자연재해 중 상위 5위안에 4개의 가뭄이 기록될 정도로 그 피해가 심각한 것으로 나타나고 있다. 우리나라 역시 5년에 한번 꼴로 심한가뭄이 발생하는 등 가뭄의 발생주기가 점차 짧아지고 있어 이에 대한 대비가 필요한 실정이다. 따라서, 본 연구에서는 가뭄지수를 이용한 통계학적 분석을 통해 과거가뭄사상을 정량적으로 평가하고자 한다. 본 연구에서는 관측자료의 신뢰성이 확보되어 있는 기상청 산하 59개 기상관측소를 대상으로 하였으며 1976~2010년(35년)의 자료를 이용하여 SPI(6)를 산정하였다. 분석방법으로는 한반도 가뭄의 발생빈도를 추정하기 위하여 Drought Spell 분석을 실시하였으며 한반도를 대상으로 극심한 가뭄에 대한 가뭄우심지역을 평가하기 위하여 지속기간별 가뭄빈도해석을 통해 SDF 곡선을 작성하고 이를 이용하여 가뭄우심도(Drought Potential Hazard Map)를 작성하였다. 가뭄단계별 발생빈도를 분석한 결과, 금강, 낙동강, 섬진강유역에서 심한가뭄과 극한가뭄단계의 발생빈도가 높게 나타났으며 가뭄빈도해석을 통해 작성된 SDF 곡선에서도 한강유역에 위치한 서울관측소에 비해 금강, 낙동강, 섬진강 유역에 위치한 대전, 대구, 광주 관측소의 재현기간별 가뭄심도가 낮게 나타났다. 가뭄빈도해석을 통해 작성된 가뭄우심도에서는 한강 유역과 낙동강 유역의 상류에 비해 금강, 섬진강, 영산강 유역이 가뭄에 취약한 지역으로 분석되어 가뭄단계별 발생빈도와 유사한 결과를 나타내었다. 또한, 동일한 재현기간에서 지속기간이 길어질수록 가뭄의 심도가 감소하는 것으로 분석되었다. 유역별 가뭄심도를 비교한 결과에서는 재현기간 200년 빈도, 지속기간 3개월의 가뭄심도의 경우, 섬진강 유역(-2.89)에서 한강(-2.13), 낙동강(-2.72), 금강(-2.45), 영산강(-2.73)유역에 더욱 극심한 가뭄을 나타내고 있었으며 지속기간 6개월의 가뭄심도에서도 동일한 결과를 나타내었다.

• Journal of Conservation Science
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• v.16 s.16
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• pp.27-38
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• 2004

This study was performed to characterize historical paper artefacts from 16th to 19th century from Chungbuk National University Museum (CNUM) in Korea. In order to know the fiber composition, surface features and fiber orientation in historic paper artefacts, LM, SEM and EDX analysis observations were applied. Based on tested results, it was concluded that Korean historic papers from 16 to 19th century were made of paper mulberry fibers called dak, which had 2.79-16.03 m of fiber lengthes and $4.5-26{\mu}m$ of lumen widthes, and they were relatively well preserved. According to EDX analysis, the examined papers differed to the contents of inorganics. High contents of S, Si, Ca, P and Al refer to use fillers, such as gypsum, clay and talc, for paper artifacts. In particular, half of samples contained some amounts of S, Cl and Fe. Since those inorganics might be potentially harmful for the paper permanency, therefore it should be considered special restoration measures from the preservation point of view.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.21 no.1
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• pp.28-34
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• 1985

This paper describes that the characteristic of movement and the performance of the directional system of the liquid magnetic compass analyze and investigate in the kinds of compass and the coefficient of viscosity of the liquid of compass, which the horizontal magnetic field of the geo-magnetic is varied from the equator to the polar region (0.39 gauss-0.03 gauss) by use of apparatus generating artificial magnetic fields. The results are as follows; 1. It is confirmed that the measured values and the calculated values on the characteristic of damping curve by the type of compass and coefficient of viscosity has almost agree with one another. 2. As the horizontal magnetic force geo-magnetic field approaches around the equator (0.39 gauss), the horizontal magnetic field get near the polar region (0.03 gauss), its period is to be longer and the compass card prove not to be more stabilized. 3. The coefficient of viscosity of the liquid in the A, B, C, D and E compasses used in the experiment is estimated 0.03 poises, 0.02 poises, 0.02 poises, 0.015 poises and 0.048 poises respectively by computer simulation.

• Communications of Mathematical Education
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• v.13 no.1
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• pp.73-96
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• 2002

수학적인 사고력과 창의력이 강조되고 있는 요즈음 수학교육에서는, 이산수학적인 영역이 담당해야 할부분이 더욱 많아진 것으로 생각된다. 이에 발맞춰, 최근에 이산수학에 관한 연구가 활발해지고 있다. 그러나, 아직 초등학교에서 적절히 사용할 수 있는 별도의 이산수학 관련 서적이나 연구 문헌이 없어 아동들의 이산수학에 대한 관심과, 수학 성적과 이산수학의 문제 해결력과의 관계에 대하여 조사해 보았다. 이산수학의 문제들을 구성하여 아동들에게 예고 없이 평가하고 문제에 대한 수학적인 태도를 질문을 통하여 알아보고, 수학 실력이 우수한 학생과 그렇지 못한 학생들과의 이산수학 문제 해결력의 관계를 알아보고자 다음과 같은 연구 내용을 설정하였다. 이를 살펴보면 첫째, 초등 수학교육에서 이산수학에 대한 학생들의 반응에 대하여 생각해 본다. 둘째, 수학 성적과 이산수학 문제 해결과의 관계를 생각해 본다. 이상의 연구 문제를 해결하기 위해, 문헌 연구를 통하여 이산수학에 관련된 초등학교 내용을 소개하고, 문항을 구성하였다. 소개된 주제 중에서 4개의 주제(수 세기, 한 붓 그리기, 지도 색칠하기, 최소 거리 ${\cdot}$ 비용 수형도)를 선정하여 10개의 문항을 작성하였다. 조사 연구를 위한 대상은 서운 시내 2개 초등학교 5, 6학년 2개 반을 선정하였다. 각 문항의 정답율은 백분율(%)에 의하여 분석하였는데 그 결과를 살펴보면, 첫째, 수 세기의 정답율은 첫 번째 문항의 정답율이 낮았을 뿐, 다른 문항들의 정답율은 비교적 좋게 나타난 것으로 보아 문제를 이해하기 쉽게 구성하는 것이 중요하다는 것을 알게 되었다. 둘째, 한 붓 그리기와 지도 색칠하기의 문제들의 정답율은 상당히 높게 나타났는데, 그러한 것은 아동들이 직접 다양한 방법으로 시도해 봄으로써 문제를 해결할 수 있었기 때문인 것 같다. 또한 이러한 유형의 문제들은 아래 학년에도 투입해 볼 수 있을 것 같다. 셋째, 최소거리 ${\cdot}$ 비용 수형도의 문제에서는 난이도가 높은 이유도 있지만 문제 이해를 완전히 하지 못해 정답율이 무척 낮게 나온 것으로 생각된다. 넷째, 수학 성적이 높은 학생들이 대체적으로 문제 해결력이 높았던 것으로 나타났으나, 몇몇 학생들은 정반대의 결과가 나와 특이한 시사점을 제공했다. 그러한 이유로는 정형화된 문제들을 선호하고 쉽게 해결하는 아동들과, 그렇지 않은 아동들 사이의 문제 접근 방법의 차이라고 생각된다. 본 연구를 통하여 다음과 같은 제언을 하고자 한다. 첫째, 이산수학에 관련된 많은 문항을 개발하여 아동들에게 확대 투입함으로써 수학 수업의 효과와 문제 해결력을 높일 수 있을 것이라 생각된다. 둘째, 수학 실력이 떨어지는 아동들에게 보다 흥미있는 이산수학적 문제들을 제시함으로써 수학에 대한 자신감과 흥미를 높일 수 있을 것이라 생각된다. 셋째, 초등학교 과정에 알맞은 이산수학의 다른 주제도 학습 지도안과 그와 관련된 문제들을 개발하는 연구가 진행되어야 하겠다.

• KIEAE Journal
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• v.14 no.6
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• pp.99-104
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• 2014

Recently supply of low energy house is increasing which can enhance energy efficiency and indoor environment comfort. Low energy house have to secure air tightness as well as thermal performance so house become high airtightness and inevitably need heat recovery ventilator to enhance indoor air quality. However, most of current ventilation systems are one-click, controlling the entire space so it causes increasing of heating load and fan power which makes it hard to save energy. Thus, Individual Control system is required which can achieve both enhancing indoor air quality and decreasing heating load and electric fan power. Thereby, in this study, we analyzed the correlation between ventilation and fan power through mock-up experiment and measured ventilation load under individual control system. As a result, under the condition of $24^{\circ}C$ of indoor temperature for 6 month(November to April) in Daejeon, ventilation load by fan speed was $10.9{\sim}19.6kWh/m^2{\cdot}a$ when operated 24 hours and $7.6{\sim}13.7kWh/m^2{\cdot}a$ when operated 12 hours in night time. In addition, it is possible to reduce at most 60% of ventilation load under the individual control system; measured ventilation load was $7.4kWh/m^2{\cdot}a$ when operated 24 hours, and $5.5kWh/m^2{\cdot}$ when operated 12 hours in night time.

• Journal of the Korean Vacuum Society
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• v.22 no.2
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• pp.79-85
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• 2013

Rare earth ions, either $Eu^{3+}$ or $Dy^{3+}$-doped $CaMoO_4$ phosphors were synthesized by using the solid-state reaction method. The crystalline structure of all the phosphor powders, irrespective of the type and concentration of activator ions, was found to be a tetragonal system with the main diffraction peak at (112) plane. For $Eu^{3+}$-doped $CaMoO_4$ phosphors, the grain particles showed an increasing tendency and the pebble-like patterns with a very homogeneous size distribution in the range of 0.01~0.10 mol of $Eu^{3+}$ ions concentration, and the excitation spectra were composed of a broad band centered at 311 nm and weak multiline peaked in the range of 360~470 nm. The dominant emission spectrum was the strong red emission centered at 618 nm due to the $^5D_0{\rightarrow}^7F_2$ transition of $Eu^{3+}$ ions. For $Dy^{3+}$-doped $CaMoO_4$ powders, excitation spectra showed a charge transfer band centered at 303 nm and relatively weak bands resulting from the transitions of $Dy^{3+}$ ions and the main yellow emission spectrum was observed at 578 nm, which was assigned to the $^4F_{9/2}{\rightarrow}^7H_{13/2}$ transition of $Dy^{3+}$ ions.

• Journal of The Geomorphological Association of Korea
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• v.17 no.3
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• pp.59-75
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• 2010

In this study, location evaluation of the natural environment of ports in the Joseon Dynasty was carried out to investigate the outport of east coast for the conquest of Usanguk. As a result of study, there were 55 ports and naval stations in the Joseon Dynasty, including the Yeongokpo, Aninpo, Samcheokpo, Susanpo, and Wolsongpo. As a result of the restoration work in the sea level that was done in the sixth century, the sea level at that time was about 1m higher than that at present. In terms of the location type, three types were identified via natural-environment analysis. Location type I consists of a total of 21 ports suitable for defense due to the sand spit in all the sides and because it is located in the bay of small and medium rivers. Location type II is composed of 22 ports close to the open seas, and location type III consists of a total of 12 ports centering on the bay. A total of nine ports satisfied the location factor in the shortest distance analysis(targeting location type I), 15 ports in the slope analysis, 13 ports in the hinterland analysis, 13 ports in the visibility analysis, and 11 ports in the ocean current analysis. It was found in the final evaluation that the I level regions consist of two ports(Obunjin and Mangyangjin). Obunjin has a location characteristic that is advantageous for defense and that makes it suitable to serve as an anchorage harbor for a large-scale fleet as its water level is deep and as it has a wide embayment. In conclusion, Obunjin is considered the outport that has the highest possibility of serving as Isabu's departure port for the conquest of Usanguk.

• The Journal of Korean Society for Radiation Therapy
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• v.31 no.1
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• pp.33-41
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• 2019

Purpose : To evaluate the effectiveness of Jaw-tracking(JT) technique in Intensity-modulated radiation therapy(IMRT) and Volumetric-modulated arc therapy(VMAT) for radiation therapy of esophageal cancer by analyzing volume dose of perimetrical normal organs along with the low-dose volume regions. Materials and Method: A total of 27 patients were selected who received radiation therapy for esophageal cancer with using $VitalBeam^{TM}$(Varian Medical System, U.S.A) in our hospital. Using Eclipse system(Ver. 13.6 Varian, U.S.A), radiation treatment planning was set up with Jaw-tracking technique(JT) and Non-Jaw-tracking technique(NJT), and was conducted for the patients with T-shaped Planning target volume(PTV), including Supraclavicular lymph nodes(SCL). PTV was classified into whether celiac area was included or not to identify the influence on the radiation field. To compare the treatment plans, Organ at risk(OAR) was defined to bilateral lung, heart, and spinal cord and evaluated for Conformity index(CI) and Homogeneity index(HI). Portal dosimetry was performed to verify a clinical application using Electronic portal imaging device(EPID) and Gamma analysis was performed with establishing thresholds of radiation field as a parameter, with various range of 0 %, 5 %, and 10 %. Results: All treatment plans were established on gamma pass rates of 95 % with 3 mm/3 % criteria. For a threshold of 10 %, both JT and NJT passed with rate of more than 95 % and both gamma passing rate decreased more than 1 % in IMRT as the low dose threshold decreased to 5 % and 0 %. For the case of JT in IMRT on PTV without celiac area, $V_5$ and $V_{10}$ of both lung showed a decrease by respectively 8.5 % and 5.3 % in average and up to 14.7 %. A $D_{mean}$ decreased by $72.3{\pm}51cGy$, while there was an increase in radiation dose reduction in PTV including celiac area. A $D_{mean}$ of heart decreased by $68.9{\pm}38.5cGy$ and that of spinal cord decreased by $39.7{\pm}30cGy$. For the case of JT in VMAT, $V_5$ decreased by 2.5 % in average in lungs, and also a little amount in heart and spinal cord. Radiation dose reduction of JT showed an increase when PTV includes celiac area in VMAT. Conclusion: In the radiation treatment planning for esophageal cancer, IMRT showed a significant decrease in $V_5$, and $V_{10}$ of both lungs when applying JT, and dose reduction was greater when the irradiated area in low-dose field is larger. Therefore, IMRT is more advantageous in applying JT than VMAT for radiation therapy of esophageal cancer and can protect the normal organs from MLC leakage and transmitted doses in low-dose field.

• Science of Emotion and Sensibility
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• v.21 no.4
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• pp.55-62
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• 2018

The two main requirements of wearable optical fiber fabrics are that they must presuppose a high degree of flexibility and they must maintain the luminance effect in both flat and bent conformations. Therefore, woven optical fiber fabrics that satisfy the above conditions were developed by both weaving and by using computer embroidery. First, we measured the brightness of the wearable optical fiber fabric in the flat state at a total of 10 measurement points at intervals of 1 cm. Second, the wearable optical fiber fabric was placed horizontally on the forearm, where three-dimensional bending occurs, and the luminance values were recorded at the same 10 measurement points. For the woven fabric in the flat state, the maximum, minimum, average, and standard deviation luminance values were $5.23cd/m^2$, $2.74cd/m^2$, $3.56cd/m^2$, and $1.11cd/m^2$, respectively. The corresponding luminance values from the bent forearm were $7.92cd/m^2$ (maximum), $2.37cd/m^2$ (minimum), $4.42cd/m^2$ (average), and $2.16cd/m^2$ (standard deviation). In the case of the computer-embroidered fabric, the maximum, minimum, average, and standard deviation luminance values in the flat state were $7.56cd/m^2$, $3.84cd/m^2$, $5.13cd/m^2$, and $1.04cd/m^2$, respectively, and in the bent forearm state were $9.6cd/m^2$, $3.63cd/m^2$, $6.13cd/m^2$, and $2.26cd/m^2$, respectively. Therefore, the computer-embroidered fabric exhibited a higher luminous effect than the woven fabric because the detailed structure reduced light-loss due to the backside fabric. In both types of wearable optical fiber fabric the luminance at the forearm was 124% and 119%, respectively, and the light emitting effect of the optical fiber fabric was maintained even when bent by the human body. This is consistent with the principle of Huygens, which defines the wave theory of light, and also the Huygens-Fresnel-Kirchhoff principle, which states that the intensity of light increases according to the magnitude of the angle of propagation of the light wavefront (${\theta}$).