• Journal of Educational Research in Mathematics
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• v.26 no.2
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• pp.247-267
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• 2016

It has been pointed out that the mathematics textbooks according to 2009 revised national curriculum cause difficulty not by mathematical knowledge but concomitantly by words and sentences for the first graders who just started learning Korean alphabets. This study focused on the suitability of words and sentences in mathematics textbooks for elementary first grade. We analyzed the degree of difficulty and familiarity in terms of words and the structure, length, and expression in terms of sentences. The results show some causes that lead the first graders to the difficulty. In more detail, we found 108 difficult words and 6 unfamiliar words for the first graders. And it is noticed that the textbooks contain 37 compound sentences, 727 complex sentences, and 38 compound-complex sentences. They also contain 237 long sentences that are composed of 9 words or more, 168 sentences that assign two activities or more, and 52 sentences that contain three nouns or adjectives or more successively. Based on these results and discussions, we suggested several implications for writing mathematics textbooks for the lower grades in elementary school.

• Korean Journal of Microbiology
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• v.51 no.3
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• pp.280-287
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• 2015

Probiotics are microbial food supplements or components of bacteria which have traditionally been added to dairy foods for extra health boost. Our aim was to evaluate the hepatoprotective effect of Bifidobacterium adolescentis SPM0212 as probiotics, which we previously found has potential anti-hepatitis B virus activity. The study was conducted using Wistar albino rats and probiotics were treated orally for 9 days consecutively and acute liver injury was induced by administration of carbon tetrachloride ($CCl_4$) on the 7th and 8th days. Liver damage was assessed by quantifying serum activities of glutamate oxaloacetate transaminase (SGOT) and glutamate pyruvate transaminase (SGPT), as well as by histopathological examination. B. adolescentis SPM0212 significantly prevented the elevation of SGOT and SGPT levels, and reduced the negative effect of $CCl_4$ on body and organ weights. Histopathological study revealed the livers of the carbon tetrachloride treated rats showed almost complete loss of normal hepatocyte architecture, but that rats treated with B. adolescentis SPM0212 showed minimal damage and normal hepatocyte architecture. Our results suggest that B. adolescentis SPM0212 be considered useful probiotics for protecting the liver from xenobiotics and hepatitis B virus, and as well as useful as a functional food for maintaining human health.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.5
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• pp.155-164
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• 2015

This paper describes a design and implementation of CABAC decoder, which would handle HEVC syntax elements in adaptively pipelined-parallel computation manner. Even though CABAC offers the high compression rate, it is limited in decoding performance due to context-based sequential computation, and strong data dependency between context models, as well as decoding procedure bin by bin. In order to enhance the decoding computation of HEVC CABAC, the flag-type syntax elements are adaptively pipelined by precomputing consecutive flag-type ones; and multi-bin syntax elements are decoded by processing bins in parallel up to three. Further, in order to accelerate Binary Arithmetic Decoder by reducing the critical path delay, the update and renormalization of context modeling are precomputed parallel for the cases of LPS as well as MPS, and then the context modeling renewal is selected by the precedent decoding result. It is simulated that the new HEVC CABAC architecture could achieve the max. performance of 1.01 bins/cycle, which is two times faster with respect to the conventional approach. In ASIC design with 65nm library, the CABAC architecture would handle 224 Mbins/sec, which could decode QFHD HEVC video data in real time.

• Journal of the Korean Society for Railway
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• v.20 no.1
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• pp.85-98
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• 2017

In general, under the repetitive dynamic load generated by rail cars running on the track, subgrade soil experiences changes of stress conditions such as deviatoric stress (${\sigma}_d$) and bulk stress (${\theta}$). Due to the repetitive change of deviatoric stress (${\sigma}_d$) with number of loadings, the resilient modulus ($M_R$) can be obtained by using the measured resilient strain (${\varepsilon}_r$) after a sufficient number of loadings. At present, no plausible and unified test method has been proposed to obtain the resilient modulus of railway track subgrade soil. In this study, a possible test method for obtaining the resilient modulus ($M_R$) of railway track subgrade soil is proposed; this test, by utilizing repetitive triaxial compression testing, can consider all the important parameters, such as the confining stress, deviatoric stress, and number of loadings. By adapting and using the proposed test method to obtain $M_R$, $M_R$ values for compacted track subgrade soil can be successfully determined using soil obtained in three field sites of railway track construction with changing water content range from OMC. In addition, shear modulus (G) ~ shear strain (${\gamma}$) relation data were also obtained using a mid-size RC test. A correlation analysis was performed using the obtained G and $M_R$ values while considering the strain levels and modes of strain direction.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.5
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• pp.117-124
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• 2017

In this study, to evaluate the setting time, compressive strength and drying shrinkage of ordinary Portland cement and Portland blast-furnace slag cement mortar with 0, 10, 20, 30 wt.% alpha-calcium sulfate hemihydrate. As a results, as the replacement ratio of alpha-calcium sulfate hemihydrate increased, the initial setting time of ordinary Portland cement and Portland blast-furnace slag cement mortar was faster. In addition, the compressive strength decreased with increasing replacement ratio of alpha-calcium sulfate hemihydrate in both ordinary Portland cement mortar and Portland blast-furnace slag cement mortar. The strength development of Portland blast-furnace slag cement mortar with alpha-calcium sulfate hemihydrate was effective than that of ordinary Portland cement mortar. On the other hand, in the case of the mortar with alpha-calcium sulfate hemihydrate, it was confirmed that shrinkage deformation was reduced at the early age by growth pressure of needle-shaped ettringite crystals produced by incorporation of alpha-calcium sulfate hemihydrate. However, the effect of inhibiting shrinkage deformation of mortar with alpha-calcium sulfate hemihydrate was not significant as the age passed. Therefore, it is considered that the alpha-calcium sulfate hemihydrate is useful as a construction material.

• Fire Science and Engineering
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• v.31 no.3
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• pp.79-87
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• 2017

Sandwich panels which are having the both sides are bonded with a heat insulating material with an iron plate are used as factories, warehouse structures as advantages of convenience in construction at economic efficiency of material cost. However, in a panel structure constructed by continuous joining of sandwich panels, a joint portion where a panel and a panel are connected is generated. The joint part is a part which is easily vulnerable to fire because flames easily flow into the melting and deformation of the iron plate during fire. The flames flowing into the panel induce diffusion of fire by rapid burning, causing damage of human life and property. In this research, we developed a flame spread prevention plate to prevent spreading of sandwich panel. This is an improvement of the workability by the anti-spreading construction method of the existing previous research, it can be applied independently to the connecting part where the panel and the panel are coupled, designed to prevent inflow and spreading of flame did. The actual fire test of the test method of KS F ISO 13784-1 of the sandwich panel specimen was conducted and the burning behavior corresponding to the presence or absence of application of the flame spread prevention plate was grasped at the panel connection part and its effect was measured. Inserting a fire spreading plate into the test result panel connecting part is measured by delaying the flashover, prevention of collapse of the specimen, and temperature rise of the opening, effectively improving the fire safety of the panel structure It was confirmed as a method that can be secured. It is judged that panel structure will contribute to ensuring fire safety by applying the fire spread prevention construction method of various methods ensuring the workability and economy of panel connection vulnerable to fire.

• Applied Chemistry for Engineering
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• v.4 no.4
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• pp.721-730
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• 1993

Various catalysts of $Cu_xH_3-{_{2x}}PMo_{12}O_{40}{\cdot}_nH_2O$ with different x-values have been prepared and characterized by thermal analysis, X-ray powder diffraction, infrared spectroscopy, BET surface-area measurement, electron microscopy, and temperature programmed desorption of ammonia. The properties of these catalysts in acrolein oxidation have been investigated in a continuous-flow fixed-bed reactor. The catalysts lost their water of crystallization at about $200^{\circ}C$ and their constitutional water between 300 and $400^{\circ}C$. The Keggin structure of the catalysts was identified by infrared spectroscopy. The decomposition of Keggin anion, $(PMo_{12}O_{40})^{3-}$, was increased with the increase of substituted copper content and identifiable $MoO_3$ and $P_2O_5$ as decomposition products were observed. The conversion of acrolein decreased with the increase of x probably due to the decrease of specific surface area and of total amount of acid sites. But specific reaction rate and selectivity to acrylic acid were maximized at x=1.0, and it showed specific acid site distributions.

• The Journal of Engineering Geology
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• v.13 no.1
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• pp.107-127
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• 2003

After detailed geological mapping, structural and fracture-density data were collected and analyzed in the vicinity of Cheonseong and Jeongjok Mts., Gyeongsangnam-do. A extensive dextral strike-slip fault (Beopgi Fault) Parallel to Yangsan and Dongrae Faults, a dextral-transtensional-NW fault, and a few intermittent faults have been found in the study area. Based on strike and frequency, fracture system has been divided into three sets such as NNE-trending J1 ($NS-40^{\circ}E$), WNW-trending J2 ($N50^{\circ}-80^{\circ}W$), and ENE-trending J3 ($N60^{\circ}-90^{\circ}E$). According to analysis of fracture density, it is revealed as follows: (a) Jl is the combination of Y-, P-, and R-shear fractures due to the dextral strike-slip of the Beopgi Fault. (b) J2 is the preexisted fracture zone conducting the intrusion of granite. Two tensional fractures dipping to NNE and SSW respectively have been induced by intrusion of granite and followed crustal uplift. (c) J3 is the tensional fracture developed between Yangsan and Dongrae Faults having NNE trend and dextral strike-slip sense. This study aims to reduce environmental impact and insure stability of underground facilities and tunnels.

• Journal of Life Science
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• v.18 no.7
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• pp.924-930
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• 2008

Community structure refers to the number of species in a community and the pattern of distribution of individuals among those species. The purpose of this paper was to describe a statistical analysis for detecting a ecological biodiversity which is valid even though the assumption at the different sampling points is not violated spatial randomness of species. Counts and cover were determined from 10 ($20\;m{\times}20\;m$) plots in five sites of the Oncheon River which is located in Busan, Korea. Total 95 taxa (85 species, 9 varieties, and one form) were identified and measured in edge sides of this river. These were a total of present in the five sites. Overall across the fragments, mean number of species per plot differed significantly among the five sites (F=7.75, p<0.01). Shannon-Wiener functions differed significantly among plots (F=4.12, p<0.05), with the St. 1 having significantly higher value (2.380) than the others (2.206 for St. 2, 2.116 for St. 3, 2.069 for St. 4, and 0.637 for St. 5). The richness indices, R1 decreased from the upper stream of the Oncheon River to the lower stream. We used a novel way of representing community structure to show that abundance within closely related pairs of co-occurring species in the Oncheon River. The differences between the distributions for of congeners and pairs of non-congeners showed at the largest difference of the cumulative fractions of the data sets (x=0.85).

• Development and Reproduction
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• v.1 no.2
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• pp.141-156
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• 1997

1992년 1월부터 12월까지 1년간에 걸쳐 전북 군산, 선연리 조하애에서 채집된 개량조개, Mactra chinensis Philippi를 대상으로 생식세포 발달과 생식소 발달양상을 조사하기 위해 토과형 전자현미경으로 미세구조 변활르 관찰하였고, 정확한 산란기를 규명하기 위해 조직학적으로 생식주기를 조사하였다. 개량조개는 장웅이체이다. 난황형성과정은 난모세포의 발달정도에 따라 다르게 나타나고 있다. 전난황형성기 난모세포질 내에서는 핵주변 구여게 골지장치와 수많은 공포들 및 미토콘드리아들이 출현하고 있는데 이들은 차후, 지방적 형성에 관여한다. 난황형성전기 난모세포에서는 지방적 및 지질과립들이 핵막 근처에서 출현하여 피질층쪽으로 분산되는 반면, 같은 발달단계의 난모세포질의 피질구역에서는 피질과립들 (단백질성 난황과립)이 처음으로 생성되어 난황막 근처의 피질층에서 핵주변 구역쪽으로 분산 분포된다. 난황형성후기 난모세포에서는 세포질 내의 골지장치, 공포, 미토콘드리아, 그리고 조면소포체들이 자율합성에 의해 난황과립 형성에 관영하고 있다. 반면, 외인성 물질들인 지질형태의 과립들, 단백질성 물질 및 다량의 글리코겐 입자들이 생식상피 낸에서 출현하고 있는데, 이들 물질이 생식상피에서 난황막 구조물인 미세융모를 통해 난황형성 후기 난모세포의 난질 내로 통과해 들어가는 현상이 관찰되었다. 이와 같은 현상은 난황성성이 일어날 때에 hterosynthesis가 일어나고 있음을 시사한다. 완숙난모세포의 난경은 약 50-60 \mu m이고, 완숙정자 두부의 길이는 대략 3 \mu m이며, 미부의 길이는 약 30 \mu m정도이다. 정자 미부편모의 axoneme은 중앙의 2개의 미세소관(microtubule)과 주변에 위치한 9개의 2중 미세소관 (microtubule)으로 구성되어 있다. 본 종의 산란기는 5월에서 9월 중순에 걸쳐 일어나는데, 주산란시기는 해수수온이 22 \circ C 이상으로 상승하는 6, 7월이다. 따라서 1년에 산란 (번식)시기가 한번 일어나고 있음을 알 수 있다. 생식 주기는 초기활성기 (1-2월), 후기활성기 (2-4월), 완숙기 (4-9월), 산란기 (5-9월) 그리고 퇴화 및 비솰성기 (6-12월)의 연속적인 5단계로 구분할 수 있었다. 재생산에 가담할 수 있는 암, 수개체들의 군성숙도(%)를 조직학적으로 조사한 결과, 각장 3.5-3.9cm 범위의 개체는 55.5%이었고, 5cm 이사인 개체들은 재생산에 100% 참여하였다. 본 종의 암, 수개체들은 만 1년부터 재생산에 가담하는 것으로 추정된다.