• 한국염색가공학회지
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• 제30권2호
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• pp.107-116
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• 2018

Simplification of the manufacturing process in shoe making is essential to improve productivity and reduce production costs. To improve the adhesion of EVA foam used as a midsole, EVA/itaconated EPDM(EPDM-g-IA)(80/20wt%) blend was prepared using Torque Rheometer-Plasti-Corder, and 1,6-hexamethylenediamine/crosslinking agent/foaming agent/additive were mixed, followed by amidation reaction and foaming to prepare EVA/EPDM-g-IA foam for shoe midsole. In this study, we investigate the effect of the content of 1,6-hexamethylenediamine(0, 0.5, 1.0, 2.0, 3.0) on the mechanical properties, water-contact angle and adhesion of EVA/itaconated EPDM foam. As the content of 1,6-hexamethylenediamine increased, mechanical properties such as tensile strength, tear strength, tensile elastic modulus, hardness, and water-contact angle were lowered, but elongation at break and compression set(%) were increased. Both normal type and non-UV type adhesive strength increased with increasing diamine content. In particular, it was found that the adhesion strength of the non-UV type adhesion increased sharply with increasing diamine content. As a result, an adherend rupture occurs in a foam sample having a content of 1,6-hexamethylenediamine of 3phr. From this, it can be seen that the EVA/itaconated EPDM foam for shoe midsoles, which can be used for non-UV adhesion without primer and UV treatments, have been developed.

• 한국분말재료학회지
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• 제24권3호
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• pp.202-209
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• 2017

A cold-work tool steel powder is used to fabricate 3-dimensional objects by selective laser melting using a high-pressure gas atomization process. The spherical powder particles form continuous carbide networks among the austenite matrix and its decomposition products. The carbides comprise Nb-rich MC and Mo-rich $M_2C$. In the SLM process, the process parameters such as the laser power (90 W), layer thickness ($25{\mu}m$), and hatch spacing ($80{\mu}m$) are kept fixed, while the scan speed is changed from 50 mm/s to 4000 mm/s. At a low scan speed of 50 mm/s, spherical cavities develop due to over melting, while they are substantially reduced on increasing the speed to 2000 mm/s. The carbide network spacing decreases with increasing speed. At an excessively high speed of 4000 mm/s, long and irregularly shaped cavities are developed due to incomplete melting. The influence of the scan pattern is examined, for which $1{\times}1 mm^2$ blocks constituting a processing layer are irradiated in a random sequence. This island-type pattern exhibits the same effect as that of a low scan speed. Post processing of an object using hot isostatic pressing leads to a great reduction in the porosity but causes coarsening of the microstructure.

• 한국분말재료학회지
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• 제27권2호
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• pp.103-110
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• 2020

Aluminum (Al) - based powders have attracted attention as key materials for 3D printing because of their excellent specific mechanical strength, formability, and durability. Although many studies on the fabrication of 3D-printed Al-based alloys have been reported, the influence of the size of raw powder materials on the bulk samples processed by selective laser melting (SLM) has not been fully investigated. In this study, AlSi10Mg powders of 65 ㎛ in average particle size, prepared by a gas atomizing process, are additively manufactured by using an SLM process. AlSi10Mg powders of 45 ㎛ average size are also fabricated into bulk samples in order to compare their properties. The processing parameters of laser power and scan speed are optimized to achieve densified AlSi10Mg alloys. The Vickers hardness value of the bulk sample prepared from 45 ㎛-sized powders is somewhat higher than that of the 65 ㎛m-sized powder. Such differences in hardness are analyzed because the reduction in melt pool size stems from the rapid melting and solidification of small powders, compared to those of coarse powders, during the SLM process. These results show that the size of the powder should be considered in order to achieve optimization of the SLM process.

• 임산에너지
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• 제25권2호
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• pp.28-33
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• 2006

본 연구에서는 대기오염에 대한 저항성과 내충성, 항균성 등이 강하여 가로수로 많이 심어진 은행나무에 있어서, 그 잎의 파티클보드 제조 원료로서의 가능성을 모색하고자 하였다. 이를 위해 은행나무 잎을 분쇄한 다음 목재 파티클에 소량 혼합하여 파티클보드를 제조하였다. 은행나무 잎을 혼합하여 제조한 파티클보드의 물리, 기계적 성질을 조사하고 포름알데히드 방출량의 저감효과에 대해 검토하였다. 목재 파티클에 대하여 은행나무 잎을 $1{\sim}5%$ 첨가하여 제조한 파티클보드는 은행나무 잎을 첨가하지 않은 대조구에 비해 밀도, 함수율, 흡수두께팽창률 등 물리적 성질과 휨강도, 박리강도와 같은 기계적 성질은 크게 감소하지 않았으며 모두 KS 파티클보드의 기준을 만족하였다. 은행나무 잎의 혼합량에 따라 포름알데히드 방출량은 점차 감소하였으며, 특히 은행나무 잎이 3% 첨가된 파티클보드의 포름알데히드 방출량은 $2.81mg/{\ell}$에서 $1.66mg/{\ell}$로 대조구에 비해 약 40% 감소하였다. 은행나무 잎이 지닌 고유한 항균성에 덧붙여 본 연구로부터 얻어진 결과는 낙엽으로 폐기되는 은행나무 잎을 원료로 포름알데히드 방출량이 낮은 기능성 파티클보드를 제조할 수 있다는 새로운 사실을 보여주고 있다.

• 한국전자통신학회논문지
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• 제9권12호
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• pp.1415-1420
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• 2014

3D 프린터는 3D도면을 입력받아 적층가공 방식으로 재료를 쌓아 원하는 제품을 제작하는 프린터이다. 3D 프린터는 다양한 입체 제품을 출력할 수 있고, 짧은 시간 내에 제품 출력이 가능하여 다양한 분야에서 사용되고 있다. 이러한 3D 프린터는 다양한 종류의 출력방식과 재료가 있는데 본 논문에서는 이중 ABS(Acrylonitrile Butadiene Styrene)수지를 녹여 쌓는 FDM(Fused Deposition Modeling)방식을 고려한다. 이 방식을 사용한 3D 프린터는 고온에서 제품을 출력하여 짧은 시간 내에 냉각이 진행되는데, 이 과정에서 출력물의 크기나 주변 환경의 상태에 따라서 휘어짐 현상이 발생한다. 이러한 휘어짐 현상을 최소화하기 위해 현재 사용되고 있는 방법은 온도를 적정선으로 유지해주는 방식이다. 이 방식은 온도 유지를 위한 추가적인 장비가 필요하여 본 논문에서는 휘어짐 현상을 최소화하기 위한 3D 프린팅 기법을 제안한다. 제안된 방식은 제품의 최초설계 시 휘어짐 위치를 고려하여 적당한 구멍(홈)을 생성시켜 출력하는 방법을 기반으로 한다. 제안된 방법에 대한 수학적 모델을 제시하고, 성능평가를 위해 일반적인 방식을 사용한 출력물과 제안된 방법으로 설계한 출력물을 측정하고 분석한다.

• KSBB Journal
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• 제30권2호
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• pp.63-68
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• 2015

This study aimed to develop and optimize a demucilaging process of Opuntia ficus-indica var. saboten (OFI) fruit to increase its usability as functional food ingredient and food additive. Viscozyme and Novozym 33095 as multienzyme complex having a broad spectrum of carbohydrases and pectolytic enzymes, respectively, were used in enzymatic dissolution along with high hydrostatic pressure liquefaction. To optimize the liquefaction process using high hydrostatic pressure liquefying extractor, response surface methodology with 3-factor central composite design was employed with reaction factors such as temperatures (25, 32, 40, 48, and $55^{\circ}C$), pressures (20, 40, 60, 80, and 100 MPa), and times (15, 30, 45, 60, and 75 min). At optimum conditions ($25^{\circ}C$, 100 MPa, and 58.275 min) for high hydrostatic pressure liquefaction process, the processed OFI fruit juice was predicted to have viscosity at 2.917 poise, partly due to the release of free sugars such as fructose and glucose detected using HPLC-ELSA system. The results above suggests that the OFI fruit juice with decreased viscosity may be used for various manufacturing processes of food, beverage, ice cream, and cosmetics.

• 한국기록관리학회지
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• 제1권1호
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• pp.177-200
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• 2001

종이의 열화 원인은 종이의 구조, 제조공정의 내적인 요인과 온도, 습도, 빛 미생물 등에 의한 환경적 용인으로 종이는 열화를 받게 된다. 식물체를 주성분으로 제조된 종이는 제조공정에 도입된 산성 물질에 의해 쉽게 가수분해 되어 셀룰로오스를 저분자량으로 변화 시킴으로 강도 저하, 황변화를 인해 내구성이 약해져 훼손되므로 자료의 가치를 상실하게 된다. 본 연구는 도서의 산성화를 예방하고 보존수명을 연장하기 위한 탈산 처리제, 탈산 처리 장비의 국내개발을 통하여 그동안 산성화 된 도서의 훼손을 근본적으로 해결 가능하게 되었다. 본 장비의 약품의 특성은 현재 시급한 보존처리 대상물의 기록물의 주기적인 탈산처리를 실시하므로 산성화 예방 및 열화된 도서의 보존이 가능하다. 실험 결과 1회 탈산처리시 pH4.5(산성)에서 pH8.5(약알카리성)로 중화되므로 보존수명이 2-3배 연장 가능하였고 외국산 장비의 국산화로 처리 비용을 크게 줄일 수 있다.

• 한국유기농업학회지
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• 제23권4호
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• pp.659-682
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• 2015

This study was conducted to suggest ideal management system for organic materials. As the performing method of the study, surveyed results on understanding of related persons (organic farmer 846, organic materials manufacture 70 and Organic materials Auditors 7) with eco-friendly farming were used. And the opinion on unintentional pollution source contained in organic materials was surveyed additionally. The issues pointed out by organic farmers on product of organic materials were high price (60% to total), poor efficacy (16%), disorder on distribution system (13%) and containing chemicals as a pesticide (10%). And notification system for organic materials was accepted in general (positive and so so 76%) while most interviewees preferred (89%) unification of certification system dominantly. As unintentional contamination source, pollution on imported row material was indicated as major reason, and other causes were confirmed as insertion during manufacturing process, agricultural by-products using as product additive et al. Based on these surveyed results, authors suggest bellows as considerable methods for effective improvement of management system on organic material. First, establish new integrated certification system which contains standard of quality certification and notification system on organic material. Second, for evaluation of efficacy, apply relative evaluation system of significance such as Duncan's multiple test instead of existing absolute evaluation system. Third, constitute and operate selection of standard comparison subcommittee in organic Agro-materials committee in RDA.

• Toxicological Research
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• 제18권4호
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• pp.331-339
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• 2002

Phenoxy compounds, 2,4-Dichlorophenol acetoxy acid (2,4-D) and 2,4-dichlorophenol (DCP), are widely used as a hormonal herbicide and intermediate for pesticide manufacturing, respectively. In order to assess the potential of these compounds as endocrine disruptors, we studied the androgenicity of them wing in vivo and in vitro androgenicity assay system. Administration of 2,4-D (50 mg/kg/day, p.o.) or DCP (100 mg/kg/day, p.o.) to rats caused an increase in the tissue weight of ventral prostate, Cowpers gland and glands penis. These increase of androgen-dependent tissues were additively potentiated when rats were simultaneously treated with low dose of testosterone (1 g/kg, s.c.). 2,4-D increased about 350% of the luciferase activity in the PC cells transiently cotransfected phAR and pMMTV-Luc at concentration of $10^{-9}$ M. In 2,4-D or DCP-treated castrated rats, testosterone 6$\beta$-hydroxylase activity was not significantly modulated even when rats were co-treated with testosterone. In vitro incubation of 2,4-D and DCP with microsomes at 50 $\mu$M inhibited testosterone 6$\beta$-hydroxylase activity about 27% and 66% in rat liver microsomes, about 44% and 54% in human liver microsomes and about 50% and 45% in recombinant CYP3A4 system, respectively. The amounts of total testosterone metabolites were reduced about 33% and 75% in rat liver microsomes, 69% and 73% in human liver microsomes and 54% and 64% in recombinant CYP3A4 by 2,4-D or DCP, respectively. Therefore, the additive androgenic effect of 2,4-D or DCP by the co-administration of the low dose of testosterone may be due to the increased plasma level of testosterone by inhibiting the cytochrome P450-mediated metabolism of testosterone. These results collectively suggested that 2,4-D and DCP may act as androgenic endocrine disrupter by binding to the androgen receptor as well as by inhibiting the metabolism of testosterone.

• 대한토목학회논문집
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• 제31권5C호
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• pp.171-185
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• 2011

레디믹스트(Ready-mixed) 숏크리트는 전문공장에서 원재료를 건조배합 형태로 생산하여 시공현장으로 운반 및 타설되는 재료로서, 확실한 골재 품질관리가 가능하며 규격화된 재료 사용으로 시공 품질 개선이 가능하다. 특히, 현장 배치플랜트의 축소 혹은 생략이 가능하기 때문에, 설치비용 절감 및 부지확보로 인한 민원과 환경문제를 해결할 수 있는 추가적인 장점이 있다. 본 연구에서는 숏크리트 성능 향상을 위한 방법으로 혼화재 및 급결제에만 국한되어 있던 기존 연구방향을 벗어나, 골재 자체의 품질 개선을 통해 숏크리트 성능을 향상시키고자 하였다. 기초 연구에서는 국내 숏크리트 시공실태 및 공급골재의 품질파악을 실시하였고, 현장실험을 통해 레디믹스트 숏크리트의 굵은 골재 최대치수를 8mm로 결정하였다. 또한, Pilot Plant Test를 실시하여 공장생산 공정의 재료분리 현상을 최소화 하고자 하였고, 현장실험을 통해 강섬유와 동일 수준의 휨인성을 발휘할 수 있는 합성섬유의 최적 혼입량과 고로슬래그 미분말의 최적 치환율을 도출하였다.