• 한국세라믹학회지
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• 제50권6호
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• pp.378-383
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• 2013

Continuous fiber-reinforced ceramic matrix composites (CFCCs) have a complex distribution of porosity, consisting of interfiber micro pores and interbundle/interply macro pores. Owing to the complex geometry of the pores and fiber architecture, it is difficult to obtain representative microstructural features throughout the specimen volume with conventional, destructive ceramographic approaches. In this study, we introduce X-ray computed microtomography (X-ray ${\mu}CT$) to nondestructively analyze the microstructures of disk shaped and tubular $SiC_f$/SiC composites fabricated by the chemical vapor infiltration (CVI) method. The disk specimen made by stacking plain-woven SiC fabrics exhibited periodic, large fluctuation of porosity in the stacking direction but much less variation of porosity perpendicular to the fabric planes. The X-ray ${\mu}CT$ evaluation of the microstructure was also effectively utilized to improve the fabrication process of the triple-layered tubular SiC composite.

• KIEAE Journal
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• 제10권6호
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• pp.123-130
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• 2010

Indoor air quality has attracted great attention in recent years and thus the importance of managing finishing materials in terms of pollutant source control is being emphasized. Managing the finishing material at the design stage maximizes the efficiency of IAQ control at the following construction stage. However, there are insufficient investigations on the application of a specific finishing material management process, a database management system or a finishing material management process network. As a result, the main purposes of this study comprise comprehensive evaluation of IAQ performance from the selected finishing materials and auxiliary materials, application of the material management system basing on the types and characteristics of toxic substances generated from the indoor finishing materials, investigation of IAQ evaluation standard, and the overall IAQ evaluation method for the design parts. The result of this study will be the basic data to construct DBMS for management of finishing materials with respect to IAQ.

• 한국자동차공학회논문집
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• 제14권4호
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• pp.59-67
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• 2006

Recently, application of friction welded SUH35/SUH3 is increasing in the manufacturing process of automotive engine valves For securing its reliability and a reasonable strength evaluation method, it is necessary to assess stress singularity under the residual stress condition on the friction welded interface between dissimilar materials. In this paper, strength evaluation method of friction welded materials was investigated by boundary element method and static tensile testing. An advanced method of quantitative strength evaluation for SUH35/SUH3 friction welded material is to be suggested by establishing fracture criterion by using stress singularity factors.

• 열처리공학회지
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• 제12권4호
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• pp.294-302
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• 1999

Evaluation of Brinell standard hardness tester was carried out to secure its application as a national standard for Brinell hardness. Accuracies and reliabilities in load application, indenter diameter and indentation measurement were tested through evaluation of these components. The accuracies of load application for various loading conditions were within the limit of ISO and KS specifications. Errors in the indentation measurement due to the difference in personnel characters were successfully removed by utilising automatic indentation measurement system. In overall, the tester and the indentation measuring system were found to be eligible as a national standard of Brinell hardness.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집A
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• pp.280-285
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• 2000

It is very important to evaluate the surface or subsurface microstructure because of their influences on mechanical properties of materials. Surface SH-wave which is horizontally polarized shear wave traveling along near surface and subsurface layer is an attractive technique for material evaluation. The destructive method is widely used for the estimation of material degradation but it has a great difficulty in preparing specimens from in-service industrial facilities. In this study, nondestructive evaluation for degraded structural materials used at high temperature though surface SH-wave method is discussed. 2.25Cr-1Mo steel specimens which were prepared by the isothermal aging heat treatment at $650^{\circ}$ were evaluated though ultrasonic nondestructive evaluation techniques investigating the change of sound velocity, attenuation coefficient and amplitude spectra. In addition, it has verified experimentally the frequency-dependence of attenuation coefficient though wavelet analysis method.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 봄 학술논문 발표대회
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• pp.27-28
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• 2021

For Barrier-Free certification, the floor and ground surfaces must be finished with materials that are not slippery, flat, and have low-impact in fallis. However, the BF Certification Act does not provide specific methods to meet these regulations. In performance-based design, the responsibility of proving the performance rests with the building owner and architect, so quantitative evaluation indexes are needed to select suitable materials. Furthermore, changes in performance after completion should be checked periodically in 'As-Is' conditions. There are various methods for slips, trips and falls risk assessment, causing confusion for users. In this study, the results of previous studies on the evaluation methods of slips, trips and falls were considered closely, and each quantitative evaluation index that can be used in the new construction and maintenance phase was presented.

• 분석과학
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• 제18권6호
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• pp.552-558
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• 2005

환경 대기 중에 미량 농도로 존재하는 악취 물질의 측정을 위한 ppm 수준의 다이메틸설파이드($(CH_3)_2S$) 가스 인증표준물질(CRM)을 개발하였다. 이 표준가스는 $(CH_3)_2S$의 농도 수준이 10 umol/mol이고 질소압력이 1500 psi로서, 알루미늄 실린더에 제조되었고, 3년 동안에 0.2% 수준의 안정성을 보였다. 동시에 제조된 표준가스 실린더 4병의 $(CH_3)_2S$ 농도를 가스크로마토그래프-불꽃이온화검출기(GC-FID)로 비교하여 0.4% 수준의 제조 재현성과 0.25%의 중량 및 순도의 표준불확도를 확인하였다. 개발된 $(CH_3)_2S$표준가스의 인증값은 10 umol/mol 수준이었고, 순도, 혼합. 제조, 분석, 흡착성 및 안정성을 모두 고려하여 결정한 인증값의 상대 확장불확도는 1.1%(95%의 신뢰수준, k=2)이었다.

• 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.

• 한국의류산업학회지
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• 제19권3호
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• pp.302-311
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• 2017

The purpose of this study is to develop an aesthetic and functional bicycle wear for new senior women in their 50s and 60s. We developed bicycle wear that is friendly to bicycling posture and reflects the preference of new senior women. Both the expert group and the subject group evaluated the appearance, completeness of clothing and motion functionality. The results are as followed: First, in the evaluation result of the expert group regarding the appearance and completeness of clothing, high scores are given to design, materials, color scheme, the trends suitability as well as the appearance with regard to clothing fitness. Second, in the results of the evaluation of the appearance and movement functionality targeting the subject groups, movement functionality was rated higher than appearance. In the case of the appearance evaluation, adhesion of both jacket and pants was rated very highly, which is considered to come from the elasticity of the material. In the functionality evaluation, what were pointed out as inconvenient details in the prior studies were found to be all improved and the sleeves and armpit parts were rated highly. Therefore, the pattern design and the usage of the materials suggested in this study were found to be very suitable in the movement on the ride of bicycle.

• 열처리공학회지
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• 제15권3호
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• pp.127-135
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• 2002

Shore hardness test was developed in 1906 to overcome the limit of Brinell hardness test. However, the detailed requirements on the tester was not clearly specified except the scale, i.e., 100 HS for high carbon steel and 10 HS for soft brass. As a result, the shore hardness was used for quite long time without well established standards. For the establishment of hardness standards, standard tester, standard procedure, and standard hardness block must be provided. So far the standard of Shore hardness was maintained by correlating Shore hardness scale to Vickers hardness through converting equation. This is the so called converted Shore hardness and it is not the true Shore hardness standard strictly. In this paper, the possibility of establishing Shore hardness standard based on the Shore standard hardness tester is reported.