• Structural Engineering and Mechanics
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• 제19권2호
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• pp.217-230
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• 2005

A steel silo traditionally consists of a cylindrical and a conical shell. In order to facilitate emptying operations, the cylinder is placed on local supports. This may lead to dangerous stress concentrations and eventually to local instability of the cylindrical wall. In this contribution, the locally supported cylinder is strengthened by means of ring stiffeners and longitudinal stiffeners and the effect of their dimensions on the buckling stress is investigated. This study leads to a number of diagrams, each of them representing the effect of one of the dimensions on the buckling stress. In each diagram, the failure pattern corresponding to the buckling stress is indicated.

• Archives of Pharmacal Research
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• 제25권4호
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• pp.453-456
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• 2002

Tonin(Persicae Semen) is the herb medicine that contains amygdalin as a major ingredient. Amygdalin in water is decomposed into benzaldehyde, HCN, and glucose by emulsin, a hydrolysis enzyme in tonin. A useful and practical method for the optimum extraction condition of amygdalin without enzymatic hydrolysis is required. The extraction yield of amygdalin of natural formula to nin was 0.1 % from crude powders, 1.4% from small pieces, 3.5% from half pieces and 2.4% from whole pieces. The extraction yield of amygdalin of outer shell-eliminated to nin was 0.3% from crude powders, 1.4% from small pieces, and 3.5% from half pieces and whole pieces respectively. The extraction yield of amygdalin was most high when using the size larger than half.

• Applied Microscopy
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• 제52권
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• pp.12.1-12.8
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• 2022

The microstructure of diatom frustules found in mud sediments along the coast of Boryeong- city, South Korea, was observed using a scanning electron microscopy (SEM), and the constituent elements of diatoms were analyzed using energy-dispersive X-ray spectroscopy (EDS). Diatom frustules and clay minerals were present in the SEM images of the mud powder. High-magnification SEM images revealed that the surface of the frustules contained identically shaped circular pores, measuring 1 ㎛ in diameter, arranged at regular intervals. This study revealed that the diatom shell fragments in the mud powder ranged in size from 3 to 30 ㎛, with an average thickness of approximately 2.5 ㎛. The elements Si, Al, Fe, K, Na, Mg, and Ti were detected while analyzing the frustule constituents, with Si being the primary component with the highest content.

• 폴리머
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• 제39권1호
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• pp.78-87
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• 2015

$30-50{\mu}m$의 입도를 갖는 마이크로캡슐을 목표로 poly(acrylonitrile-co-methyl methacrylate)를 쉘로, n-octane을 코어로 하는 코어-쉘 구조의 열팽창 마이크로캡슐을 합성하였다. SPG 멤브레인 유화 후 현탁 중합하여 기존의 현탁 중합대비 균일한 입자를 합성하였다. 또한 네 가지 안정제 및 다섯 가지 가교제의 종류와 함량에 따른 캡슐의 합성을 진행하였다. Poly(vinyl alcohol)을 안정제로 하여 합성한 캡슐의 표면이 매끈하면서도 균일한 형태를 보였으며, 액체 탄화수소가 코어에 캡슐화된 양 또한 우수하였다. 또한 가교제로 1,4-butnaediol methacrylate (BDDMA)를 첨가했을 때 평균입경 $36.8{\mu}m$의 입자가 균일하게 합성되었다. 또한 BDDMA를 0.05 mol% 함량으로 합성한 입자의 캡슐화 정도가 가장 우수하였다.

• 한국건축시공학회지
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• 제15권6호
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• pp.579-587
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• 2015

자기치유성능을 가지고 있는 자기치유제를 함유하고 있는 마이크로 캡슐을 콘크리트 표면의 고분자 매트릭스층에 적용하였다. 메타크릴레이트를 코어물질로 하고 폴리 우레아포름알데히드를 캡슐막 구성물질로 하는 미세캡슐을 고분자 매트릭스 안에 첨가하여 콘크리트 표면에 코팅하였다. 콘크리트 표면에 미세균열이 형성되고 전파될 때, 균열이 전파되는 위치에 있는 캡슐이 파괴되어 치유체가 균열면 사이로 흘러나오게 되고, 균열에 스며든 단량체가 햇빛에 의해 중합반응을 일으켜 균열이 자기치유 되는 현상을 고찰한다. 자기치유성능평가는 흡수성, 투수성 실험 및 광학현미경을 통한 관찰로 확인하였다. 결과적으로 제시된 자기치유시스템은 콘크리트 균열부의 부분적인 복원을 위해 사용할 수 있음을 확인하였다.

• 공업화학
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• 제27권4호
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• pp.449-454
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• 2016

본 연구에서는 구형의 폴리스티렌 구슬을 틀로 사용하여, 크기분포가 좁으면서 속은 비어있고 벽이 다공성인 구조의 탄소 마이크로 캡슐을 합성하였다. 폴리스티렌의 표면은 무기물인 실리카졸이 쉽게 입혀질 수 있도록 폴리비닐피롤리돈(PVP)을 코팅하여 변조하였다. PVP가 코팅된 PS 마이크로 입자표면에 SBA-16 졸을 부착시킨 다음, 실리카층에 존재하는 중간 크기의 세공 내에 탄소원을 채워 넣는 음각식 형뜨기법을 적용함으로써 속이 빈 구조의 탄소 마이크로캡슐을 제조하였다. 탄화과정을 거치고 틀로 사용한 다공성 실리카입자를 HF로 용해하면, 좁은 입자크기분포를 갖는 중간세공이 함유된 계란껍질형의 탄소입자를 얻을 수 있었다. 계란껍질형 탄소 마이크로캡슐 입자의 다공성과 전기화학적 특성은 XRD, SEM, TEM, 질소분자 흡/탈착분석법 및 cyclic voltammetry법으로 평가하였다. 이들 탄소입자는 슈퍼캐패시터와 같은 전자재료로서 유효하게 사용될 만한 높은 전기전도도와 용량을 나타내었다.

• Composites Research
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• 제15권2호
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• pp.32-39
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• 2002

본 연구에서는 자가치료제를 저장할 수 있는 마이크로캡슐을 제조하기 위만 공정절차를 제시하고 자가치료제가 저장된 마이크로캡슐을 제조하였다. 이때 자가치료제는 DCPD(dicyclopentadiene), 마이크로캡슐은 요소-포름알데히드 수지로 구성되어 있으며 레이저 회절법을 이용한 입도분석기를 통해 마이크로캡슐의 크기와 입도분포를 측정하였다. 또만 DSC를 통해 자가치료제, 마이크로캡슐 박막을 형성하는 요소-포름알데히드의 수지, 자가치료제가 저장된 마이크로캡슐 등에 대한 열분석을 수행하였으며 자가치료제가 저장된 마이크로캡슐에 대해 TGA를 통해 연속적인 온도증가 및 일정한 온도 조건 하에서의 열안정성을 평가하였다. 연구결과에 따르면 자가치료제가 저장된 마이크로캡슐은 마이크로캡슐의 박막이 연소되기 전까지는 박막 자체가 자가치료제의 증발을 막아 주어 자가치료제를 안정적으로 저장할 수 있음을 알 수 있었다.

• International Journal of Industrial Entomology and Biomaterials
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• 제13권1호
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• pp.7-14
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• 2006

A breeding programme was initiated during 2001 to introduce sex-limited larval markings to a productive multivoltine breed - BL67 from an inbred sex-limited line, MY1 (SL) maintained at Central Sericultural Research and Training Institute, Mysore. Introgressive hybridization, recurrent backcrossing for six generations followed by sib-mating resulted in synthesis of a new multivoltine silkworm breed BL67 (SL) with sex-limited larval markings. The new breed was studied for combining ability by crossing with eight bivoltine breeds viz., $NB_4D_2,\;CSR_2,\;CSR_2 (SL),\;CSR_2,\;CSR_4,\;CSR_8,\;CSR_{18}\;and\;CSR_{19}$. General combining ability effects of the new breed showed its superiority over the popular Pure Mysore by expressing significant GCA effects for six out of twelve characters whereas the results are on par with the original multivoltine breed. The hybrid $BL67(SL){\times}CSR2(SL)$ excelled in several quantitative characters such as pupation rate (90.2%), cocoon weight (1.97 g), cocoon shell weight (40 cg), cocoon shell ratio (20.3%), filament length (918 m), denier (2.96), raw silk percentage (14.96%) and neatness (90 p). Studies on cocoon size variability revealed that the cocoons of $BL67(SL){\times}CSR2(SL)$ were found comparatively uniform showing less standard deviation of 6.55 and co-efficient of variation of 3.91 %. The suitability of newly developed breed for easy grain age operation and commercial exploitation with promising hybrid have been discussed.

• 한국물환경학회지
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• 제29권3호
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• pp.420-427
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• 2013

In this study, the ecological characteristics of Limnoperna fortunei were surveyed as a preceding research to solve the problem such as biofouling or biowaste caused by those organisms in the closed water pipeline. Limnoperna fortunei was collected not in the main reaches of Somjin River but inside and outside of the intake tower which is located in the lower part of Sueo Reservoir. The dense populations were found at the inlet mouth and near part of the pipeline. Their byssuses were formed as a thick and tightly interwind mat. The rusted parts of the pipeline hold relatively more shells than those of the normal parts. Average count of the numbers ranged $12.1{\sim}136.5ind./m^2$ through the sampling stations (A,B and C). The amount of attached shells at each station were A=386, B=258, and C=71, respectively. The relationships of shell height-length and shell length-width were proportional. The majority sizes in each station ranged A=20.01~22.00 mm (33.9%), B=10.01~14.00 mm (51.2%), and C=18.01~20.00 mm (22.5%), 24.01~26.00 mm (21.1%), respectively. Most of the bigger size of shells on C station was found dead. The ecological habitat seemed less suitable for Limnoperna fortunei when they located farther away from the intake tower of reservoir. From now on, it is necessary to consider the continuous monitoring of this organism.

• Structural Engineering and Mechanics
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• 제56권4호
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• pp.667-694
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• 2015

The suspended dome system is a new structural form that has become popular in the construction of long-span roof structures. Suspended dome is a kind of new pre-stressed space grid structure that has complex mechanical characteristics. In this paper, an optimum topology design algorithm is performed using the enhanced colliding bodies optimization (ECBO) method. The length of the strut, the cable initial strain, the cross-sectional area of the cables and the cross-sectional size of steel elements are adopted as design variables and the minimum volume of each dome is taken as the objective function. The topology optimization on lamella dome is performed by considering the type of the joint connections to determine the optimum number of rings, the optimum number of joints in each ring, the optimum height of crown and tubular sections of these domes. A simple procedure is provided to determine the configuration of the dome. This procedure includes calculating the joint coordinates and steel elements and cables constructions. The design constraints are implemented according to the provision of LRFD-AISC (Load and Resistance Factor Design-American Institute of Steel Constitution). This paper explores the efficiency of lamella dome with pin-joint and rigid-joint connections and compares them to investigate the performance of these domes under wind (according to the ASCE 7-05), dead and snow loading conditions. Then, a suspended dome with pin-joint single-layer reticulated shell and a suspended dome with rigid-joint single-layer reticulated shell are discussed. Optimization is performed via ECBO algorithm to demonstrate the effectiveness and robustness of the ECBO in creating optimal design for suspended domes.