• Journal of KIISE:Information Networking
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• v.34 no.3
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• pp.226-238
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• 2007

In this paper, we present a novel fully distributed topology control protocol that can construct the multiple-ring topology of Minimal Connected Dominating Set (MCDS) as the transport backbone for mobile ad hoc networks. It makes a topology from the minimal nodes that are chosen from all the nodes, and the constructed topology is comprised of the minimal physical links while preserving connectivity. This topology reduces the interference. The all nodes work as the nodes of the distributed parallel Boltzmann machine, of which the objective function is consisted of two Boltzmann factors: the link degree and the connection domination degree. To define these Boltzmann factors, we extend the Connected Dominating Set into a fuzzy set, and also define the fuzzy set of nodes by which the multiple-ring topology can be constructed. To construct the transport backbone of the mobile ad hoc network, the proposed protocol chooses the nodes that are the strong members of these two fuzzy sets as the clusterheads. We also ran simulations to provide the quantitative comparison against the related works in terms of the packet loss rate and the energy consumption rate. As a result, we show that the network that is constructed by the proposed protocol has far better than the other ones with respect to the packet loss rate and the energy consumption rate.

• Progress in Medical Physics
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• v.19 no.1
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• pp.35-41
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• 2008

The main benefit of proton therapy over photon beam radiotherapy is the absence of exit dose, which offers the opportunity for highly conformal dose distributions to target volume while simultaneously irradiating less normal tissue. For proton beam therapy two patient specific beam modifying devices are used. The aperture is used to shape the transverse extension of the proton beam to the shape of the tumor target and a patient-specific compensator attached to the block aperture when required and used to modify the beam range as required by the treatment plan for the patient. A block of range shifting material, shaped on one face in such a way that the distal end of the proton field in the patient takes the shape of the distal end of the target volume. The mechanical quality assurance of range compensator is an essential procedure to confirm the 3 dimensional patient-specific dose distributions. We proposed a new quality assurance method for range compensator based on image processing using X-ray tube of proton therapy treatment room. The depth information, boundaries of each depth of plan compensatorfile and x-ray image of compensator were analyzed and presented over 80% matching results with proposed QA program.

• Journal of the Korean Society of Radiology
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• v.8 no.7
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• pp.455-459
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• 2014

We grew the $Li_6Gd(BO_3)_3:Ce^{3+}$ scintillator and determined the scintillation and thermoluminescence properties for X-rays. The emission spectrum of $Li_6Gd(BO_3)_3:Ce^{3+}$ is located in the range of 370~500 nm, peaking at 423 nm an 455 nm, due to the $4f{\rightarrow}5d$ transition of $Ce^{3+}$ ions. The fluorescence decay time of the crystal is composed three components. The fast component is 60 ns (25%), the intermediate component is 787 ns (29%) and the slow component is $5.9{\mu}s$ (46%) of the crystal. The after-glow is caused by the electron and hole traps in the crystal lattice. We determined physical parameters of the traps in the crystal. The thermoluminescence trap are composed two traps. The determined activation energy (E), kinetic order (m) and frequency factor (s) of the first trap are 0.65 eV, 1.01 and $6.9{\times}10^8s^{-1}$. And, the determined activation energy, kinetic order and frequency factor of the second trap are 0.96 eV, 1.79 and $3.1{\times}10^{12 }s^{-1}$, respectively.

• Journal of Animal Environmental Science
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• v.9 no.2
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• pp.69-78
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• 2003

In this study, the energy conversion equipment from the radiation energy to mechanical energy by using n­pentane as the operating fluid was constructed and the performance to pump the water was tested for the utilization of solar powered water pump. The equipment was designed optimally, after the theoretical analyses of the water pumping head and water quantity per cycle were done. The pentane vapour temperature in the condenser and the temperature of the outlet water from the condenser became lowered and the heat transfer rate became higher with decreasing the water inlet level to the condenser. The temperature difference between the condenser and the water tank was significant. Therefore, the distance between the water tank and condenser was recommended to be shorten and the diameter of their connecting pipe was recommended to be narrow in order to reduce the resistance of the fluid passage and improve the heat transfer rate. The amount of water pumped was 1.6­2.4 liters. Mass flow rate of the cooling water became lowered when the cooling water pipe was prolonged from the condenser to improve the heat transfer rate.

• Journal of Radiation Protection and Research
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• v.36 no.2
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• pp.59-63
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• 2011

It is important to reduce indirect scattered neutron beside direct neutron of chosen energy for designing a neutron-reference-field laboratory with neutron produced from a nuclear reaction by a accelerator. Therefore MCNPX simulation was performed with various conditions for obtaining such condition. At first in the original laboratory condition we calculated the direct neutron flux which was inserted in chamber (virtual chamber composed of air) of 0 degree (proton moving direction) for neutron flux measurement and the scattered neutron flux which is inserted in the chamber after scattering wall or bottom. In the result, the scattered neutron which was inserted after scattering bottom is more than that which was inserted after scattering the others. Therefore MCNPX simulation was again performed with removing the concrete bottom and with removing the concrete bottom and digging 1 m in the ground. In the result of removing concrete bottom and digging 1 m in the ground, scattered neutron which was inserted after scattering bottom became less than that which was inserted after scattering the others.

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.6
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• pp.829-836
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• 1995

This study was performed to evaluate the relationship between dietary, blood and urinary levels of lead and blood pressure and serum lipids in 30 healthy adult living in rural area of Korea. Analysis for the nutritional status of subjects were performed by 3-day dietary intake record, duplicated diet collection, 24-hour urine collection, and venous blood sampling before anthropometry. The mean daily intakes of lead estimated for 3 days was $120.1{\pm}22.0\mu\textrm{g}$. The blood levels and 24-hour urinary excretion of lead were $10.8{\pm}3.6\mu\textrm{g}/dl\;and\;36.5{\pm}9.5\mu\textrm{g}$, respectively. The systolic and diastolic blood pressure were $113.0{\pm}16.9mmHg\;and\;76.7{\pm}12.1\;mmHg$. The serum levels of total cholesterol, triglyceride, HDL-cholesterol, LDL-cholesterol and ${\beta}-lipoprotein$ were $158.8{\pm}32.9mg/dl,\;104.6{\pm}48.8mg/dl,\;45.7{\pm}9.9mg/dl,\;92.2{\pm}28.5mg/dl\;and\;426.4{\pm}141.5mg/dl$, respectively. There was no significance in the relation between lead and blood pressure. In the relation between lead and serum lipids, it showed negative correlation with lead intake and HDL-choleterol at the level of significance of p<0.01. But there was no significance in the relation between lead and serum levels of otehr lipids.

• 한국해양학회지
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• v.22 no.3
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• pp.207-215
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• 1987

The Keum River Estuary was investigated two times in April and July, 1986, to study process controlling chlorophyll distribution in estuarine waters. During the surveys, distribution patterns were studied for chlorophyll-a, nutrients, ph, SPM (Suspended Particulate Matter), DO (Dissolved Oxygen), temperature, salinity, etc. During April survey(low-discharge period), sea water penetrated to Kangkyung, about 35km upstream from the constructing weir, while in July (high-discharge period) only to 3 km upstream from the weir,In April SPM showed very high concentrations (500mg/l)on the average. But very low concentrations(about10mg/l)were observed in July due to high discharge of fresh water.Chlorophyll-a concentrations showed large variations both in time and space :much higher concentraations in July than in April and sharp decrease in concentrations at the fresh water-sea water interface (April:$6.5\mu\textrm{g}/{\ell}$ for fresh waters and 41.4\mu\textrm{g}/{\ell}$ forestuarine waters). Differebce ub chlorophyll-a concentrations for these two surveys appear to be caused mainly by the difference in effectiveness of penetrating lights controlled by SPM in the waters. Sharp decrease in chlorophll-a at the fresh water-sea water interface is believed to be resulted from mass mortality of fresh water phytoplankton caused by changes in osmotic pressure in the region. Observations in the same regions such as increase in AOU(Apparent Oxygen Utilization)and ammonia, decrease in PH,probably resulted through decomposition processes of dead planktons,furtuer support the idea.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.161-162
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• 2011

최근 광전자 분야에서는 미래 에너지 자원에 대한 관심과 함께 GaN 기반 태양전지 연구가 활발히 진행되고 있다. GaN 물질은 높은 전자 이동도와 높은 포화 속도 등 광전자 소자에 유리한 광, 전기적 특성들을 가지고 있다. 또한, In의 함량을 변화시켜가며, 0.7eV에서 3.4eV까지 밴드갭을 조절함으로써, 자외선부터 적외선까지 태양빛 스펙트럼의 대부분을 흡수할 수 있는 장점이 있다. InGaN 태양전지의 효율을 높이기 위해서는 In의 함량을 늘려 밴드갭을 줄이는 것이 중요하다. 하지만 GaN 와 InN 간의 격자 부정합으로 인해 In 함량이 높은 단결정 InGaN 층을 두껍게 성장 하는 것이 어렵다. 때문에 GaN 기반 태양전지 관련 연구 그룹들이 태양전지의 효율 향상을 위해 활성층에 양자우물(MQWs) 구조, Supper Lattice (SLs) 구조와 같이 얇은 InGaN/GaN 층을 주기적으로 반복하여 적층함으로써 높은 조성의 In을 함유한 상질의 InGaN/GaN 층을 성장하는 연구들을 진행해 왔다. 본 연구에서는, p-i-n 구조와 MQW 구조를 갖는 InGaN 기반 태양전지를 제작하여, 각각의 특성을 분석해 봄으로써, In0.1Ga0.9N 태양전지 활성층의 구조에 따른 장/단점에 대해 논의하였다. 먼저 MOCVD를 이용하여 200 nm의 i-In0.1Ga0.9N 활성층을 갖는 p-i-n 구조와 In0.19Ga0.81N/GaN(3 nm/8 nm) MQWs (8 periods) 구조를 갖는 태양전지 에피를 각각 성장하였고, 그 후 공정을 통해 그림 1과 같이 InGaN 태양전지 소자를 제작하였다. 그 후, 각 태양전지의 전류/전압 곡선과 외부양자효율을 측정하여 그림 2와 같은 결과를 얻었다. p-i-n과 MQW 샘플의 외부양자효율은 각각 ~70%, ~25%로 측정 되었다. MQW 샘플의 외부 양자효율이 높지 않음에도 불구하고 p-i-n 구조에 비해 높은 In 함량을 가지고 있으므로, 더 넓은 파장의 빛을 흡수하여, 높은 단락전류(0.778 mA/cm2)를 보이고 있다. 또한 p-i-n 구조에 비해 높은 개방전압(2.3V)를 가지고 있으므로, MQW 샘플이 약 17% 정도 높은 변환효율(1.4%)를 보이고 있다. 이후 추가적으로 p-i-n 과 MQW 구조의 InGaN 태양전지에 나타나는 Voc와 Jsc의 차이를 Polarization 효과를 비롯한 다양한 측면에서 분석해 보고자 한다.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.41 no.5
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• pp.592-599
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• 1996

The variations of asparagine and aspartic acid contents among the soybean varieties and in the different parts of soybean sprout after the different durations of storage were investigated. Asparagine and aspartic acid are known to have the detoxifying effects on acetaldehyde, which is highly toxic metabolites in the process of alcohol metabolism in the human body. The contents of asparagine and aspartic acid of beansprout showed continuosuly increasing trends along with the days to cultivation with a great varietal difference, especially in the roots. The duration of seed storage did not affect contents of asparagine content; the longer storage decreased aspartic acid content remarkably.

• Journal of Sensor Science and Technology
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• v.7 no.2
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• pp.131-139
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• 1998

$CdS_{0.67}Se_{0.33}$ single crystal was grown by vertical sublimation method of closed tube physical vapour deposition. The (0001) growth plane of oriented single crystals was confirmed from the back-ref1ection Laue patterns. From the Hall effects by van der Pauw method, the as-grown $CdS_{0.67}Se_{0.33}$ single crystals were found to be n-type semiconductors. The mobility appeared to be decreased by lattice scattering at temperature range from 150K to 293K and by impurity scattering at temperatures ranging from 30K to 150K In order to explore its applicability in photoconductive cells, we measured the ratio of photo-current to dark-current (pc/dc), maximum allowable power dissipation (MAPD), spectral response and response time respectively. The results indicated that for the samples annealed in Cu vapour the photoconductive characteristics are best. We obtained sensitivity of 0.99, the value of pc/de of $1.84{\times}10^{7}$, the MAPD of 323mW and the rise and decay time of 9.3 ms and 9.7 ms, respectively.