• Journal of The Korean Association For Science Education
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• v.30 no.7
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• pp.901-907
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• 2010

The purpose of this study is to analyze methods for measuring the size of the Earth, put forth in 6 different Korean 8th grade science textbooks. The research questions are as follows: 1) Do they adequately map out the experiments for measuring the size of the earth by using the concept of the sun's altitude? 2) Do they reduce the size of the sun like as the Earth is similarly downsized to the globe? 3) Do they suggest the precise experimental conditions for selecting two equal longitudinal spots for measuring the size of the earth? 4) Do they design adequate experiments for exact measurement? 5) Do they offer a proportional expression for seeking the size of globe which is easily understood by students? 6) Do they develop experiments to measure actual size of the earth? Four graduate students and one researcher took part in this study. All conditions were unanimously agreed upon by the participants. The results are as follows. First, one publishing company must include the concept of the sun's altitude to accurately measure the size of the Earth. However, some textbooks fail to mention this. As such, the concept of the sun's altitude must be introduced to accurately measure the size of the Earth. Second, a reduced size globe is used as the actual earth so; the sun should be factored in with a reduced light value. Third, you have to lay a stress on two points at the same longitude. In other words, a shadow located at the same longitude from two randomly selected points. Most textbooks mention two points at the same longitude but two of them design the experiment with a shadow at the same longitude. Fourth, we need a method to precisely measure the angle between a stick and its shadow. The angle between the stick and the tip of its shadow is the sun's altitude difference. Fifth, we need to present more specific proportional expressions for calculating the size of the globe. Only 3 out of the 6 texts employed a proportional expression. Sixth, we need to calculate the size of the earth by accurately presenting the scale of the globe to attain the goal of the experiment. Two of the texts analyzed, designed the experiment for the purpose of calculating the size of the globe. Three of the texts designed their experiments to calculate the radius of globe which is not even relevant to the purpose of experiment.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.1
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• pp.107-111
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• 2009

In this paper, the power added efficiency(PAE) of a Doherty amplifier has been improved by applying Photonic Bandgap(PBG) characteristics on the output of amplifier. As a result of the high order harmonics termination, excellent improvement in PAE, maximum output power as well as linearity is obtained. The PAE is improved as much as relatively 35% compared with a conventional Doherty amplifier. Moreover, size of LPF is reduced by PBG characteristics. Therefore the whole amplifier circuit size is considerably reduced by diminishing in size of the LPF as compared with a Doherty amplifier using conventional LPFs.

• Journal of Magnetics
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• v.7 no.3
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• pp.106-114
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• 2002

To reduce the grain size and the media noise in a typical CrMo/CoCrPtB longitudinal media, a sputtering process which includes the exposure of oxygen onto the surface of CrW$_x$ (x=0, 25, 50, 75, 100 at.%) and CrTi$_{15}$ seedlayers with the thickness of 0.5 nm have been utilized. The main results are: (1) the media grain size and the media noise are reduced when using CrW$_x$ (x=0, 25, 50 at.%) seedlayers, and not reduced when using CrTils or CrW$_x$ (x=75, 100 at.%) seedlayers, (2) AES and RHEED results suggest that W seedlayer, which has the highest melting point, forms layer-like film with very small and dense island grain, due to its high free surface energy and low mobility. On the other hand, CrW$_{50}$ and Cr seedlayers, which have lower melting point than W seedlayer, form island film, (3) to effectively reduce the media grain size and improve the media signal to noise ratio, it is essential to utilize a very thin Cr-based seedlayer with high affinity for oxygen and which forms island-like structure, such as CrW$_{50}$ seedlayer.

• Journal of Advanced Navigation Technology
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• v.15 no.5
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• pp.774-780
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• 2011

This paper presents a Bagley polygon and Gysel divider using open-stub loaded transmission line. The structure of slow-wave characteristic consists of small transmission line and shunt capacitive open stub that have reduced characteristic impedance and phase velocity, so we can implement the small circuit size. To validate the slow-wave characteristics, we are implemented the slow-wave characteristic of Bagley polygon and Gysel divider at center frequency 2.1 GHz. Its characteristics are same, but the circuit size is reduced above 15 % respectively.

• Journal of the Korean Operations Research and Management Science Society
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• v.21 no.3
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• pp.215-225
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• 1996

For an undirected stochastic network G, the 2-terminal reliability of G, R(G) is the probability that the specific two nodes (called as terminal nodes) are connected in G. A. typical network reliability problem is to compute R(G). It has been shown that the computation problem of R(G) is NP-hard. So, any algorithm to compute R(G) has a runngin time which is exponential in the size of G. If by some means, the problem size, G is reduced, it can result in immense savings. The means to reduce the size of the problem are the reliability preserving reductions and graph decompositions. We introduce a net set of reliability preserving reductions : the $K^{4}$ (complete graph of 4-nodes)-chain reductions. The total number of the different $K^{4}$ types in R(G), is 6. We present the reduction formula for each $K^{4}$ type. But in computing R(G), it is possible that homeomorphic graphs from $K^{4}$ occur. We devide the homemorphic graphs from $K^{4}$ into 3 types. We develop the reliability preserving reductions for s types, and show that the remaining one is divided into two subgraphs which can be reduced by $K^{4}$-chain reductions 7 polygon-to-chain reductions.

• 대한상한금궤의학회지
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• v.7 no.1
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• pp.29-43
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• 2015

Objective : The purpose of this paper is to report the improvement of 3 patients with uterine fibroid treated by herb medication based on Shanghanlun disease pattern identification diagnostic system. Methods : According to 'Disease Pattern Identification Diagnostic System based on Shanghanlun Provisions', they were diagnosed with Taeyang-byung, Yangmyung-byung. They took different herb medications more than 8 weeks according to their diagnosis. The size of uterine fibroid was estimated by ultrasonography. Results : The size of uterine fibroid reduced from 3.94cm to 2.55cm on first patient, 5.20cm to 4.86cm on second patient, 12.63cm to 7.77cm on third patient. Conclusions : Herb medication not only reduced the size of uterine fibroid but also improved symptoms such as dysmenorrhea, vaginal bleeding, pelvic discomfort, fatigue. In addition, this is the first case report treating the uterine fibroid with herb medication of shanghanlun in Korea.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.3
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• pp.471-481
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• 1995

Measurement factors for the dielectric properties of low dielectric loss materials (tan${\dalta}{\le}10^{-4}$) were investigated using the dielectric rod resonator method. It was shown that the relative conductivity (${\sigma}_{r}$) should be controlled within a 5% to obtain the standard deviations of less than 0.07 for permittivity .epsilon.r and 0.06${\times}10^{-4}$ for tan.delta.respectively. Surface resistivity (R$_s$) could be reduced when the surface roughness of parallelled conducting plate was less than 0.07 .mu.m. Measurement error for the permittivity was $\pm$0.02% independent of probe loop size, whereas the error in Q value was reduced with the decrease in probe loop size and also with the increase in the absolute values of Q. Reliable Q values were determined with the probe loop size of less than 4mm. The accurate for the distance between the measuring probe loop and the sample could be obtained when the insertion loss of resonant frequency ranged -15dB - -30dB.

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.5
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• pp.377-381
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• 2006

A study was carried out to determine a suitable light intensity and inoculum size for the growth of Rhodopseudomonas palustris strain B1. The pollution reduction of sago effluent using free and immobilised R. palustris cells was also evaluated. The growth rate in glutamatemalate medium was highest at 4 klux compared to 2.5 and 3 klux. The optimal inoculum size was 10% (v/v). Both the COD and BOD of the sago effluent were reduced by 67% after three days of treatment. The difference in biomass production or BOD and COD removal with higher inoculum sizes of 15 and 20% was minimal. This could be attributed to limited nutrient availability in the substrate. The use of immobilised cells of R. palustris reduced the pollution load 10% less compared to pollution reduction by free cells. Hence, there was no significant difference in using free or immobilised cells for the treatment of sago effluent.

• Journal of Welding and Joining
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• v.30 no.5
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• pp.34-39
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• 2012

This study was conducted to investigate the microstructure and mechanical properties of friction stir lap joints. Invar 42 and SS 400 were selected as the experimental materials, and friction stir welding was carried out at a tool rotation speed of 200 rpm and welding speed of 100 mm/min. The application of friction stir welding to Invar 42 effectively reduced the grain size in the stir zone; the average grain size of Invar 42 was reduced from $11.5{\mu}m$ in the base material to $6.4{\mu}m$ in the stir zone, which resulted in an improvement in the mechanical properties of the stir zone. The joint interface between Invar 42 and SS 400 showed a relatively sound weld without voids and cracks, and the intermetallic compounds with $L1_2$ type in lap jointed interface were partially formed with size of 100 nm. Moreover, the hook in the advancing side of Invar 42 was formed from SS 400, which contributed to maintenance of the tensile strength. The evolution of microstructures and mechanical properties of friction stir lap jointed Invar 42 and SS 400 are also discussed herein.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.7
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• pp.1427-1436
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• 1997

Turbo codes, decoded through an iterative decoding algorithm, habe recently been shown to yidel remarkable coding gains close to theoretical limits in the Gaussian channel environment. This thesis presents the performance of Turbo code through the computer simulation. The performance of modified Turbo code is compared to that of the conventional Turbo codes. The modified Turbo code reduces the time delay in decoding with minimal effect to the performance for voice transmission sytems. To achieve the same performance, random interleaver the size of which is no less than the square root of the original one should be used. Also, the modified Turbo code is applied to MC-CDMA system, and its performance is analyzed under the Rayleigh Fading channel environment. In Rayleigh fading channel environment, due to the amplitude distortion caused by fading, the interleaver of the size twice no less than that in the Gaussian channel enironment was required. In overall, the modified Turbo code maintained the performance of the conventional Turbo code while the time delay in transmission and decoding was reduced at the rate of multiples of two times the squared root of the interleaver size.