• Steel and Composite Structures
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• 제13권6호
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• pp.571-586
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• 2012

The paper addresses some key issues related to the design of composite slabs with cold-formed profiled steel sheets. An experimental programme is first presented, involving six composite slab specimens tested with a view to evaluating Eurocode 4 (EC4) provisions on testing of composite slabs. In four specimens, the EC4-prescribed 5000 load cycles were applied using different load ranges resulting from alternative interpretations of the reference load $W_t$. Although the rationale of the application of cyclic loading is to induce loss of chemical bond between the concrete plate and the steel sheet, no such loss was noted in the tests for either interpretation of the range of load cycles. Using the recorded response of the specimens the values of factors m and k (related to interface shear transfer in the composite slab) were determined for the specific steel sheet used in the tests, on the basis of three alternative interpretations of the related EC4 provisions. The test results confirmed the need for a more unambiguous description of the m-k test and its interpretation in a future edition of the Code, as well as for an increase in the load amplitude range to be used in the cyclic loading tests, to make sure that the intended loss of bond between the concrete slab and the steel sheet is actually reached. The study also included the development of a special-purpose software that facilitates design of composite slabs; a parametric investigation of the importance of m-k values in slab design is presented in the last part of the paper.

• Elastomers and Composites
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• 제52권4호
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• pp.249-256
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• 2017

The history of polyurethane is relatively shorter compared to that of the other polymers, though its importance has grown rapidly. Due to its unique properties, polyurethanes are widely applied in various fields. In particular, the automotive industry is one of the important application fields. To date, polyols and isocyanates used in the polyurethane industry are generally of petrochemical origin. Recently, owing to the oil crisis, legislation, and growing awareness towards environmental preservation, the demand for more sustainable and eco-friendly raw materials has increased. In this paper, the latest research and development trends in polyurethane applications were reviewed, with a focus on the automobile industry in areas such as seat comfort, noise reduction, light weight, biomass-based polyurethane, and recycling.

• 한국전자거래학회지
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• 제3권1호
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• pp.69-80
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• 1998

CALS has been a hot issue in the information-related industry in the world in order to achieve the competitive advantage of a firm or a nation. Nontheless, while there is an abundance of literature advocating the importance of introducing CALS, little attention has been given to the analysis of processes to be applied by CALS. This research conducts a case study on Firm H, investigating its processes for which CALS should be deployed and prioritizing these processes. Based on the analysis of the interviews with CALS experts who are familiar with the processes of Firm H, this paper concludes that CALS must be applied to the processes of the purchase/supply for Firm H, followed by such processes as the development of telephone exchangers, the operations management, and the service.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2005년도 춘계종합학술대회
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• pp.928-930
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• 2005

With an increasing importance of the information security issues, the efficienct calculation process in terms of finite field level is becoming more important in the Elliptic curve cryptosystems. Serial multiplication architectures are based on the Mastrovito's serial multiplier structure. In this paper, we manipulate the numerical expressions so that we could suggest a 3-times as fast as (3x) the Mastrovito's multiplier using the polynomial basis. The architecture was implemented with HDL, to be evaluated and verified with EDA tools. The implemented 3x GF (Galois Field) multiplier showed 3 times calculation speed as fast as the Mastrovito's, only with the additional partial-sum generation processing unit.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1994년도 FIFTH WESTERN PACIFIC REGIONAL ACOUSTICS CONFERENCE SEOUL KOREA
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• pp.836-841
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• 1994

This paper describes the global vibro-acoustic troubleshooting approach, used to identify and separate different sources of noise and vibrations on a boilerfeed pump testrig. The pump serves for rotor dynamic research of a EC-funded BRITE-Euram profect. This approach resulted in the identification of local structural flexibilities in the connections between the machinery and the base plate. The relative importance of the modes during normal operation is revealed by comparison with operational deformation shapes. The use of sound intensity mapping allowed to calculate the total sound power and to rank the equipment according to its sound power contribution. High acoustic levels were found and related to the fluid drive and to the piping system. Modification of the piping section resulted in a reduction of noise and vibration levels along the test loop and smooth operation in a wide suction pressure range.

• The Korean Journal of Physiology and Pharmacology
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• 제24권6호
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• pp.529-543
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• 2020

In contrast to ventricular myocytes, the structural and functional importance of atrial transverse tubules (T-tubules) is not fully understood. Therefore, we investigated the ultrastructure of T-tubules of living rat atrial myocytes in comparison with ventricular myocytes. Nanoscale cell surface imaging by scanning ion conductance microscopy (SICM) was accompanied by confocal imaging of intracellular T-tubule network, and the effect of removal of T-tubules on atrial excitation-contraction coupling (EC-coupling) was observed. By SICM imaging, we classified atrial cell surface into 4 subtypes. About 38% of atrial myocytes had smooth cell surface with no clear T-tubule openings and intracellular T-tubules (smooth-type). In 33% of cells, we found a novel membrane nanostructure running in the direction of cell length and named it 'longitudinal fissures' (LFs-type). Interestingly, T-tubule openings were often found inside the LFs. About 17% of atrial cells resembled ventricular myocytes, but they had smaller T-tubule openings and a lower Z-groove ratio than the ventricle (ventricular-type). The remaining 12% of cells showed a mixed structure of each subtype (mixed-type). The LFs-, ventricular-, and mixed-type had an appreciable amount of reticular form of intracellular T-tubules. Formamide-induced detubulation effectively removed atrial T-tubules, which was confirmed by both confocal images and decreased cell capacitance. However, the LFs remained intact after detubulation. Detubulation reduced action potential duration and L-type Ca²⁺ channel (LTCC) density, and prolonged relaxation time of the myocytes. Taken together, we observed heterogeneity of rat atrial T-tubules and membranous ultrastructure, and the alteration of atrial EC-coupling by disruption of T-tubules.

• 한국항행학회논문지
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• 제27권6호
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• pp.770-775
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• 2023

최근 디지털 데이터 양의 기하급수적 증가는 데이터 처리 시스템의 중요성을 부각시켰다. 이 연구는 클라우드 컴퓨팅 (CC; cloud computing), 엣지 컴퓨팅 (EC; edge computing), 그리고 UAV (unmanned aerial vehicle) 기반 지능형 에지 컴퓨팅 (UEC; unmanned aerial vehicle-based intelligent edge computing) 간의 성능을 비교하였으며, 특히 회랑감시와 같은 실시간 대용량 데이터 처리 상황에 초점을 맞추었습니다. UAV 기반 지능형 에지 컴퓨팅은 이동성과 특수 환경에서의 대규모 데이터 처리 및 분석에 높은 효과성을 보인다. 이러한 연구 결과를 바탕으로 각 상황에 맞게 최적화된 시스템 선택 방법론을 제안한다.

• 한국환경보건학회지
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• 제50권3호
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• pp.201-211
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• 2024

Background: Organic ultraviolet (UV) filters are widely used in sunscreen products and have been identified as an emerging contaminant. Organic UV filters co-exist with multiple components, but their mixture toxicity remains largely unknown. Objectives: We investigated the toxicity of single and binary mixtures of commonly used UV-filters using the human adrenocarcinoma (H295R) cell line. Methods: After exposure to non-cytotoxic concentrations of avobenzone (AVO), homosalate (HS), octisalate (OS), octinoxate (OMC), and octocrylene (OC), the levels of testosterone (T) and 17β-estradiol (E2) were measured. The median effective concentration (EC₅₀) values for the E2 of the individual substances were used to determine the mixture effect of four binary combinations: OMC+AVB, OMC+HS, OMC+OS, and OMC+OC. The synergistic, additive, and antagonistic effects of the mixture were determined by calculating toxic units (TU). To examine the mechanism of mixture toxicity, eight genes involved in steroidogenesis were analyzed using the real-time polymerase chain reaction. Results: The significant increase in E2 in H295R cells exposed to AVO, HS, OS, OMC, and OC suggest an estrogenic effect of the tested UV-filters. A significant decrease in T was observed in cells exposed to HS and OS. EC₅₀ values for E2 increase were 105 nM for AVO, 110 nM for HS, 120 nM for OS, 55 nM for OMC, and 80 nM for OC. Both binary mixtures consisting of OMC+HS and OMC+OS have synergistic effects. Conclusions: Our results showed that five types of UV-filter substances increase E2 in H295R cells. We examined the mixture toxicity in terms of increased estrogenicity and confirmed that E2 significantly increased when OMC was mixed with a salicylate-based UV-filters. These findings highlight the importance of determining the impact of UV filter mixtures.

• 공학교육연구
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• 제12권1호
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• pp.31-41
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• 2009

과학기술의 발전이 가속화되고 사회에 미치는 파급력이 커짐에 따라 과학기술자의 사회적 책임 향상과 전문직 윤리에 대한 관심이 높아지고 있다. 공학분야에서는 특히, EC2000의 도입과 공학교육인증기준이 체계화와 더불어 공학윤리교육의 중요성이 강조되고 있다. 하지만 공학과 윤리의 결합은 단순히 원칙적 선언에 의해 확보될 수 없으며 교육 시스템안에서 어떻게 제도화될 수 있고 실행 가능한 지에 대한 체계적 접근이 필요하다. 이 연구는 공학윤리 교육 제도화의 전제 조건이 되는 인식의 전환과 공학의 일상적 경험에 근거한 윤리 교육이 필수적임을 주장하고 있다. 1980년대까지 확립된 공학윤리교육의 의의와 한계를 밝히면서 최근 발전하고 있는 공학윤리교육의 특성과 지향점을 살펴본다. 또한 현재 이루어지고 있는 공학윤리교육의 유형을 분석하여 각 유형별 쟁점과 특성을 분석한다. 이제 막 발전하기 시작한 우리나라의 공학윤리교육은 각 대학의 주어진 여건과 상황을 고려하여 독립형 혹은 전공결합형 공학윤리 교육을 적절히 조합하여 추진하는 것이 바람직하다. 무엇보다 공학과 공학 이외 분야의 해당 전문가들 사이의 협력 연구와 교육이 선행되어야 할 것이다.

• 생물환경조절학회지
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• 제31권4호
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• pp.444-451
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• 2022

최근 토마토 수경재배가 증가하며 장기 재배가 일반화 되고 있다. 수경재배에서는 작물의 양분과 수분 요구도를 고려하여 적정 양액을 공급하는 것이 생산성, 자원의 이용, 환경보전 측면에서도 매우 중요한데 장기재배에서는 계절적인 환경변화가 심하므로 이것을 고려한 급액 관리가 매우 중요하다. 따라서 코이어 배지를 이용한 토마토 장기재배에서 급액량이 생육과 수량에 미치는 영향을 구명하고자 하였다. 온실 외부에 설치된 일사 센서로 적산일사를 기준으로 급액 횟수를 조절하였으며, 생육시기별로 급액 기준을 변경하며 4수준(High, Medium high, Meidum low, Low)으로 급액량을 달리 처리하였다. 급액량이 많을수록 배액률이 높았으며 배액의 EC가 지나치게 높아지는 것을 방지 할 수 있었다. 재배기간이 경과하면서 배액 EC가 높아졌는데 급액량이 적은 처리일수록 상승 폭이 컸다. 초장은 급액량이 가장 적은 처리구가 다른 처리구에 비하여 작았고 마디수와 화방의 발생 수는 급액량에 영향을 받지 않았다. 착과수는 전체적으로는 급액량의 영향을 크게 받지 않았으나 저온기에 발생한, 12-15화방에서는 급액량이 가장 많았던 처리구가 착과수가 적었다. 배꼽썩음과는 급액량이 가장 적은 처리구가 많았고 발생 시기도 빨랐다. 과실의 크기는 High 처리구가 컸으나 전체 수량은 Medium high 처리가 가장 많았다. 시험의 결과로 코이어를 이용한 토마토 수경재배에서 급액량이 근권의 양·수분 안정화와 생산성에 미치는 영향과 적정한 급액 관리의 중요성을 확인할 수 있었다. 따라서 최근에 보급되고 있는 복합환경제어시스템에 근권의 정보를 기준으로 정밀급액제어 알고리즘을 적용한다면 수경재배 제어기술 발전과 더불어 작물의 생산성 향상에도 기여할 수 있을 것으로 판단되므로 이에 대한 지속적인 연구가 필요할 것이다.