• Product Safety
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• s.24
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• pp.29-34
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• 1994

UL(Underwriters Laboratories Inc)은 미국의 대표적인 비영리 민간 안전시험기관이다. UL마크는 세계적으로 권위가 있다. 특히 미국내에서 소비자인지도 및 주정부의 강제적용에 힘입어 UL인증없이는 시장 유통이 어려운 실정이다. 공산품에 대한 단체 임의 인증 마크로서 전기, 전자제품, 건축재료, 해양장비(선박)등을 대상으로 화재, 폭발관련 안전성 시험에 합격하고 공장심사 및 사후관리 협정을 맺은후 마크가 부여 된다.

• Composites Research
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• v.29 no.6
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• pp.321-327
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• 2016

In this study, tests and finite element analyses were performed regarding compression after impact strength for laminated composite structures of unidirectional carbon fiber reinforced plastic widely used in structural materials. Two lay-up sequences of composite laminates were selected as test specimens and four impact energy conditions were applied respectively. Impact and compressive strength tests were conducted in accordance with ASTM standards. Impact damages in test specimens were analyzed by using non-destructive inspection method of C-Scan, and compression after impact strengths were calculated with compressive test results. Progressive failure analysis method that can progressively simulate damages and fractures of fiber/matrix/lamina/laminate level was used for impact and compressive strength analyses. All analysis results including contact force, deflection, impact damages, compressive strengths, etc. were compared to test results, and the validity of analysis method was verified.

• Journal of Aerospace System Engineering
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• v.18 no.2
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• pp.64-70
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• 2024

The demand for safety certification of Light Unmanned Aerial Vehicles (LUAVs), weighing between 25kg and 150kg, is rapidly increasing in Korea. Unfortunately, the number of LUAV safety certification failures is also on the rise, with manufacturing quality issues being identified as the main culprit. However, there is a lack of quality system standards for manufacturers within the LUAV safety certification system. As a result, this paper aims to analyze the domestic safety certification system and the quality standards set by the American Society for Testing and Materials (ASTM) for small Unmanned Aerial Systems (sUAS). The goal is to establish quality system inspection standards specifically tailored for LUAV manufacturers. To achieve this, we propose additional inspection items that reflect the characteristics of the manufacturing quality system. These items will be identified through on-site inspections of LUAV manufacturers, ensuring that the resulting quality system standard aligns with the actual situation of domestic manufacturers. In order to gauge the feasibility and effectiveness of the proposed quality system standard, we conducted a survey of seven domestic LUAV manufacturers.

• International Journal of Highway Engineering
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• v.13 no.2
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• pp.159-166
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• 2011

This research was performed to evaluate physical properties of polysulfide epoxy overlay material for bridge deck as part of a review for possibility of domestic application of polymer concrete for bridge deck pavement. In order to evaluate strength characteristics, compressive strength, flexural strength and bond strength were tested, and, for durability characteristics, chloride ion penetration resistance and freeze/thaw resistance were tested along with ultraviolet rays impact evaluation. The tests showed that the results met the criteria suggested by the American Concrete Institute in terms of compressive strength, flexural strength and bond strength. However, in terms of the strengths measured at various test temperatures, it was found that the epoxy material was highly dependent on temperature, and, therefore, this should be considered at the time of domestic application of the epoxy material later. Deflection characteristics was checked through flexural strength test and it was found that bridge deck pavement using the epoxy material was excellent compared to bridge deck pavement using asphalt. Furthermore, the results of chloride ion penetration resistance test and freeze/thaw resistance test were also excellent. In the evaluation of ultraviolet rays impact on epoxy slurry mixture, reduction of strain was noticed with increased strength, but the deflection characteristics after exposure to ultraviolet rays was better than the existing acryl polymer concrete. Therefore, it is concluded from the research that the polysulfide epoxy overlay material has the physical properties that are appropriate to pavement of bridge deck.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.2
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• pp.129-139
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• 2008

Marine ecotoxicological standard method was applicated using marine rotifer and benthic copepod as primary consumer of marine ecosystem. Marine rotifer, Brachionus plicatilis and benthic copepod, Tigriopus japonicus were designated as standard test species with the endpoints of 24hr neonate mortality (24hr $LC_{50}$) and 48hr population growth (48hr $EC_{50}$) for rotifer, and 48hr nauplius mortality (48hr $LC_{50}$) for benthic copepod. Tests method was referred to those of ASTM (American Society for Testing and Materials) with the replacement of test species which are widely distributed in Korean waters. The two species showed a wide tolerance on salinity ($5{\sim}35\;psu$) and can be easily cultured in small space even they were not as sensitive as in the mortality test using the nauplius of marine invertebrates. However, these species revealed the significant "concentrationresponse relationship" tested with ocean disposal wastes, and reproducibility using cadmium as standard reference material between laboratories. Accordingly, these two species have good potential as test species for marine ecotoxicological test species. Also, we strongly recommend that at least one of these species be included in the test species of "battery test" in marine bioassay.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.8
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• pp.5039-5044
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• 2015

In this study, we evaluated corrosion behavior of a common rolling stock axle material, RSA1, in seawater. 3-electrode electrochemical cell experiment was conducted using artificial sea water, fabricated according to ASTM-D1141 set by American Society for Testing and Materials, where the corrosion current density and corrosion rate were determined to be $18.3{\mu}A/cm2$ and 0.217 mm/yr, respectively, by employing potentiodynamic test method and impedance spectroscopy method. Considering the fact that life time of railway car is ~25 years, the expected corrosion layer depth is 5mm. Constant-current corrosion test was conducted to accelerate the corrosion process, to reach corrosion periods of 1,3 and 4 years based on Faraday's law, followed by tension tests where the reduced specimen gauge cross-section was re-measured for stress calculation. While no apparent corrosion-related changes in mechanical properties were observed in the elastic regime, the reduction in ductility of the material was found to be increased as the corrosion period increased. The results of this study are expected to be basic corrosion data for the design of rolling stock axles, which will be operated in the sea water environment.

• Journal of the Korean Institute of Gas
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• v.26 no.1
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• pp.27-33
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• 2022

As the scale of explosions diversifies along with the expansion of gas handling and storage facilities, studies on explosion-proof facilities in preparation for accidents is being actively conducted. The gastight door blocks the expansion pressure caused by blast waves or internal fires, and at the same time protects the personnel and equipment inside. For gastight doors, the regulations related to explosion-proof design are not clearly presented, and studies on the explosion pressure resistance performance evaluation of the facility are insufficient. In this study, the gastight door was modeled in a 3D shape with reference to the regulation ASTM regarding the gastight door standard. Afterwards, evaluation for blast-resistant performance of gastight door using Numerical simulation was evaluated by using ANSYS Explicit Dynamics to compare the deformation.

• Journal of the Korean Magnetics Society
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• v.8 no.6
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• pp.341-345
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• 1998

Magnetic shielding effect of cylinderical ahields made of commericial amorphous ribbons has been studied. The shell-arrangement-order of double shell shield has been found to show a striking differencein shielding factor. In low applied field region, a 2605CO-2705M-shield (outer shell: 2605CO, inner shell: 2705M) yields two times higher shielding factor than a 2705M-2605CO-shield (outer shell: 2705M, inner shell: 2605CO). The reasons are as follows: In case of 2605CO-2705M-shield, the outer shell is not easily saturated and effectively shields the applied field. In addition, the inner shell shows high shielding factor in the field shielded by the outer shell. In case of 2705M-2605CO-shield, the outer shell is saturated at very low-field as well as the inner shell shows low shielding factor in the field shielded by the outer shell.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.196-196
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• 2016

치과나 기공소로부터 높은 원가로 인한 재료선택에 어려움을 겪고 있어 귀금속 금합금의 물성을 가질 수 있도록 하면서 가격급등으로 인한 문제 해결하기 위한 비귀금속 합금으로 대체가 필요하기에 이에 따른 연구가 이루어져 국산 제품의 상품화를 위해 파라듐을 이용하여 적합한 새로운 합금을 개발하는 것이 필요하다. 치과용 골드합금은 미국치과의사 협회의 구정에 의하면 1형부터 4형까지 분류하고 있으며 3형에 해당하는 강도와 기계적인 특성을 갖도록 파라듐으로 대체하는 연구가 진행중이거나 시판되고 있다. 따라서 본 연구에서는 2형, 3형 및 4형을 대체가능하도록 팔라듐을 기반으로 한 새로운 합금을 설계하고 합금의 성분원 소인 Au(1~5), Pd(20~25), Ag(70~75), In(1.5) 및 Zn(2)등으로 조성을 변화시켜 측량 후 합금을 제조하기 위하여 아르곤 분위기하의 진공아크용해로를 이용하여 용해하였다. 정량된 금속을 진공아크 용해로에 장입하고 용해는 균질한 합금이 되도록 최소한 6회 이상 용융을 실시하며 합금성분의 손실이 발행하지 않도록 보정을 하였다. 합금의 미세조직 관찰을 위하여 샘플을 고속 다이아몬드 정밀 절단기(Acculom-5, STRUERS, Denmark)를 이용하여 절단한 후 2000 grit의 Sic 연마지에서 단계적으로 $0.3{\mu}m$ 알루미나 분말까지 연마한 후 초음파 세척을 하였다. 준비한 시편은 KCN과 $(NH_4)_2S_2O_8$을 1:1로 혼합한 부식액으로 에칭한 후 OM과 SEM을 이용하여 조직을 관찰하였으며 각 샘플의 성분변화는 EDS 분석을 통해 확인하고 결정구조는 XRD를 사용하여 분석하였다. 경도시험은 비커스경도시험기를 이용하여 5kg의 하중을 30초간 작동시켜 압흔을 연결된 micron으로 평균값을 측정하였다. 각 시편의 부식거동은 POTENTIOSTAT(Model PARSTAT 2273, EG&G, USA)을 이용하여 구강 내환경화 유사한 $36.5{\pm}1^{\circ}C$의 0.9% NaCl에서 실시하였다. 인가전위는 -1500mV에서 1000mV까지 1.67 mV/min의 주사속도로 인가하여 시험을 수행하였으며 분극곡선으로부터 부식전위와 부식전류밀도 및 부동태영역의 전류밀도로 금속의 용출거동을 조사하였으며 부식이 끝난 시편은 FE-SEM과 EDS를 사용하여 조사하였다. 기계적인 특성은 Pd-Ag에 3wt%의 Au를 첨가한 합금이 Pd-Ag에 1.5wt%합금을 첨가한 경우에 비하여 기계적인 특성이 증가하고 내식성이 크게 증가하였다. 이들 합금에 Cu를 11wt%를 첨가한 경우는 비커스경도가 200이상으로 높게 나타났지만 내식성이 크게 감소하였다.