• 한국전기전자재료학회논문지
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• 제30권9호
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• pp.535-540
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• 2017

The changes in the electrical characteristics of CMOS ICs due to coupling with a narrow-band electromagnetic wave were analyzed in this study. A magnetron (3 kW, 2.45 GHz) was used as the narrow-band electromagnetic source. The DUT was a CMOS logic IC and the gate output was in the ON state. The malfunction of the ICs was confirmed by monitoring the variation of the gate output voltage. It was observed that malfunction (self-reset) and destruction of the ICs occurred as the electric field increased. To confirm the variation of electrical characteristics of the ICs due to the narrow-band electromagnetic wave, the pin-to-pin resistances (Vcc-GND, Vcc-Input1, Input1-GND) and input capacitance of the ICs were measured. The pin-to-pin resistances and input capacitance of the ICs before exposure to the narrow-band electromagnetic waves were $8.57M{\Omega}$ (Vcc-GND), $14.14M{\Omega}$ (Vcc-Input1), $18.24M{\Omega}$ (Input1-GND), and 5 pF (input capacitance). The ICs exposed to narrow-band electromagnetic waves showed mostly similar values, but some error values were observed, such as $2.5{\Omega}$, $50M{\Omega}$, or 71 pF. This is attributed to the breakdown of the pn junction when latch-up in CMOS occurred. In order to confirm surface damage of the ICs, the epoxy molding compound was removed and then studied with an optical microscope. In general, there was severe deterioration in the PCB trace. It is considered that the current density of the trace increased due to the electromagnetic wave, resulting in the deterioration of the trace. The results of this study can be applied as basic data for the analysis of the effect of narrow-band high-power electromagnetic waves on ICs.

• 분석과학
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• 제12권4호
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• pp.299-305
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• 1999

Electrolyte as cathode glow discharge(ELCAD)는 용액 중에 포함된 미량 중금속을 연속 자동 측정하기 위한 새로운 플라스마 source로서 주로 원자방출법에 의하여 원소들을 측정한다. 그러나 수은의 경우 원자 방출법보다는 원자 흡수법을 주로 적용한다. 본 연구에서는 기존의 원자흡수분광기의 원자화부분을 ELCAD cell로 대치하여 원자흡수법에 의하여 수은을 측정하였다. 일반적으로 원자방출법에 의하여 원소들의 방출선측정시 용액의 pH가 1.0에서 가장 안정한 플라스마와 가장 큰 방출세기를 나타내었으나 수은인 경우 pH 3.0에서 가장 흡광도가 높았다. 그러나 플라스마의 안정도는 pH가 1.0 일 때가 가장 좋은 관계로 흡광도의 % RSD 값은 pH 1.5 용액에서는 0.35% 이었으며 pH 3.0인 검액에서는 3.6%를 나타내었다. 두 검액에 대해 각각 검량곡선을 작성하였을 때 모두 양호한 직선성을 보였으며, 각각의 검출 한계를 구한 결과, pH 1.5 용액은 약 40 ppb, pH 3.0 용액은 10 ppb level 이었다.

• 한국산업보건학회지
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• 제4권2호
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• pp.157-167
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• 1994

This study was conducted to analyze the relationship between the types of fiber and its content and the levels of airborne fiber concentrations at eight parking lots where sprayed insulation material was found on the walls and ceilings. Also this study was designed to find the relationship between the levels of airborne fiber concentrations and such variables as air current, humidity, total exhaust volume, surface condition of insulation material and building age. The results obtained were as follows : 1. No significant correlation was found between the levels of airborne tiber concentration and the building age, air current, humidity, total exhaust volume, space and the number of traffics. 2. A significant correlation was found between the levels of airborne fiber concentration and the MMMF content of the insulation material(r=0.7594). However, no significant correlation was found between the levels of airborne fiber concentration and total fiber content of insulation material. 3. The differences of the airborne fiber concentrations among Cateogory 1, 2 and 3 classified by the degrees of surface insulation material maintenance were very significant. 4. Two bulk samples contained 30% crodicolite and 1% anthophylite. The MMMFs, in all parking lots, included mineral wool, cellulose fiber, trace cellulose fiber, trace tiber glass and vermiculite. 5. The mean value and the range of airborne fiber concentrations at 8 parking lots were $0.0239{\pm}0.0095f/cc$ and 0.0054-0.0447 f/cc, respectively. The fiber concentrations of 35 out of 38 samples(92%) were over 0.01 f/cc which is the Environment Administration's recommended asbestos level for the underground space. This study suggests that most of building insulation materials used in Korea, contain MMMF and sometimes asbestos. Currently, MMMF pollution levels may exceed the Environment Administration's recommended level for underground space. It has been found that airborne fiber concentrations increased significantly with MMMF content and with the maintenance condition of surface material. Therefore, it is recommended that a proper management technique should be developed and immediately implemented since the conditions of surface material will be gradually deteriorated due to building age and usage. Since health hazards of the MMMF, similar to those of asbestos, are being gradually acknowledged, a proper management technique which is applicable to control total airborne fiber concentrations, both asbestos and MMMF, be developed and an acceptable indoor air standard be promulgated as early as possible.

• 한국항해항만학회지
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• 제39권4호
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• pp.277-283
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• 2015

함정에 사용되는 선체재료로는 연강, 고장력강, 고강도강, 알루미늄 합금 및 복합재료 등이 있다. 그 중 함정의 선체는 수밀과 강도의 유지 및 탑재장비의 지지 등 기본적인 기능을 위하여 철강 재료를 주로 사용하고 있다. 함정의 주 임무는 해양에서 작전을 수행하는 것이므로 해수에 의한 선체 부식이 필연적으로 발생하게 된다. 선체의 부식을 방지하기 위하여 도장 방법, 희생양극법 및 강제 전류 방식이 사용되고 있다. 특히 Al 및 Zn을 활용한 희생양극법의 경우 부식특성 개선을 위하여 인듐(In), 카드뮴(Cd) 및 납(Pb) 등의 중금속이 첨가되어 있다. 하지만 이러한 중금속은 인체 및 환경에 매우 유해하므로 전 세계적으로 사용이 점차 규제되고 있다. 이에 본 논문에서는 인체 및 환경에 무해한 미세원소(Ma, Ca, Ce 및 Sn)를 첨가하여 Al 및 Zn 합금을 제조하였다. 제조된 함정용 Al 및 Zn 희생양극의 효율 특성 측정을 위하여 SEM, XRD, 동전위 분극실험 및 전류효율 평가를 실시하였으며, 실험결과 Al-3Zn-0.6Sn 및 Zn-3Sn 합금의 양극 성능이 다른 합금 보다 효율성이 우수하였다.

• 멤브레인
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• 제31권2호
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• pp.87-100
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• 2021

최근 오염물질 수위의 급격한 상승세와 더불어 가속화되는 자연환경 파괴로 인해 다양한 환경 속에 쌓이는 오염물질의 검출 및 모니터링은 현대 사회의 중요한 미션 중 하나로 자리 잡았다. 본 논문에는 멤브레인 기반의 광학 센서를 활용한 미량 오염물질 검출에 대한 최근 연구 동향이 요약되어 있다. 본 논문에 포함된 연구들은 섬유소로 이루어진 멤브레인을 검출을 위한 플랫폼으로 사용하였으며, 금속 나노 입자나 형광단을 색 변화 검출을 위해 이용하였다. 제조된 광학 센서들은 모두 적절하거나 특출한 수준의 감도를 보였고, 대부분의 센서에서 타겟 물질이 아닌 이온이나 물질에는 반응하지 않는 정확성 또한 확인되었다. 검출 플랫폼으로 이용된 섬유소 멤브레인의 물리적, 화학적 특성들은 멤브레인 합성 방법이나 색 변화를 위한 광학 물질 등을 바꾸는 방법을 통해 각 연구의 목적에 맞추어 최적화될 수 있었다. 또한, 멤브레인을 기반으로 하여 제조된 센서들은 운반이 편리하고 기계적 성질이 강해 현장에서 바로 오염물질을 검출할 수도 있다는 사실이 제시되었다. 이러한 장점 덕분에 멤브레인 기반 센서들은 식용수에서 검출된 중금속의 정량화와 자연 수질환경에서 발견되는 미량 중금속 및 유독성 항생제의 감지 등 다양한 목적을 위해 활용될 수 있었다. 몇몇의 연구에서 제조된 센서들은 항균성이나 재활용성 또한 나타내었다. 대부분의 센서들이 타겟 물질을 감지한 후 육안으로도 식별 가능한 색 변화를 보였으나, 본 논문에 포함된 많은 연구들은 형광 발산, UV-vis 분광학, RGB 색 강도 차이 등을 비교 분석한 더 상세한 검출 결과를 제시하였다.

• 해양정책연구
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• 제33권2호
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• pp.183-204
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• 2018

국제포경위원회의 상업포경금지 조치에 따라 1986년부터 대한민국에서 포경이 금지되었다. 혼획으로 사망하는 고래의 유통은 계속 이루어져 국제기구 등에서 불법포획 의혹을 제기하기도 했다. 이에 고래 유통 질서를 확립하기 위해 2011년 "고래자원의 보존과 관리에 관한 고시"가 공포되었다. 이후 정부는 고시의 내용을 수 차례 개정하며 유통 질서를 바로 잡고자 했으나, 불법포획 고래의 유통을 막기에는 여전히 부족한 부분이 있다. 본 연구에서는 이력추적 시스템 구축을 통한 고래 유통 질서 확립을 위해 위 고시의 개정을 포함한 관련 제도 개선 사항 등에 대해 연구하였다. 먼저, 불법포획 고래의 시장 진입을 제도적으로 차단하고, 혼획으로 사망한 고래만 유통이 되도록 제도의 개정이 이루어져야 한다. 그리고 불법 유통에 대한 강력한 증거 자료로 사용되는 DNA 데이터베이스를 완벽하게 구성하기 위해 시료 채집 방법과 수사용 시료의 분석 절차 등에 대한 개선이 필요하다. 끝으로 효과적인 유통 이력추적 시스템을 확립해야 한다. 기존의 시스템을 활용하기에는 법률 적용, 시민단체 반대 등 현실적인 어려움이 많기 때문에 블록체인 기술을 활용한 새로운 시스템을 개발하는 것이 보다 타당한 방법으로 여겨진다.

• Journal of Computing Science and Engineering
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• 제1권1호
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• pp.1-30
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• 2007

In this paper we have provided an extensive survey of the databases and other resources related to the current research in bioinformatics and the issues that confront the database researcher in helping the biologists. Initially we give an overview of the concepts and principles that are fundamental in understanding the basis of the data that has been captured in these databases. We briefly trace the evolution of biological advances and point out the importance of capturing data about genes, the fundamental building blocks that encode the characteristics of life and proteins that are the essential ingredients for sustaining life. The study of genes and proteins is becoming extremely important and is being known as genomics and proteomics, respectively. Whereas there are numerous databases related to various subfields of biology, we have maintained a focus on genomic and proteomic databases which are the crucial stepping stones for other fields and are expected to play an important role in the future applications of biology and medicine. A detailed listing of these databases with information about their sizes, formats and current status is presented. Related databases like molecular pathways and interconnection network databases are mentioned, but their full coverage would be beyond the scope of a single paper. We comment on the peculiar nature of the data in biology that presents special problems in organizing and accessing these databases. We also discuss the capabilities needed for database development and information management in the bioinformatics arena with particular attention to ontology development. Two research case studies based on our own research are summarized dealing with the development of a new genome database called Mitomap and the creation of a framework for discovery of relationships among genes from the biomedical literature. The paper concludes with an overview of the applications that will be driven from these databases in medicine and healthcare. A glossary of important terms is provided at the end of the paper.

• Journal of Communications and Networks
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• 제12권1호
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• pp.52-66
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• 2010

Since large objects consume substantial resources, web proxy caching incurs a fundamental trade-off between performance (i.e., hit-ratio and latency) and overhead (i.e., resource usage), in terms of caching and relaying large objects to users. This paper investigates how and to what extent the current dedicated-server based web proxy caching scheme is affected by large file transfers in a high bandwidth campus network environment. We use a series of trace-based performance analyses and profiling of various resource components in our experimental squid proxy cache server. Large file transfers often overwhelm our cache server. This causes a bottleneck in a web network, by saturating the network bandwidth of the cache server. Due to the requests for large objects, response times required for delivery of concurrently requested small objects increase, by a factor as high as a few million, in the worst cases. We argue that this cache bandwidth bottleneck problem is due to the fundamental limitations of the current centralized web proxy caching model that scales poorly when there are a limited amount of dedicated resources. This is a serious threat to the viability of the current web proxy caching model, particularly in a high bandwidth access network, since it leads to sporadic disconnections of the downstream access network from the global web network. We propose a peer-to-peer cooperative web caching scheme to address the cache bandwidth bottleneck problem. We show that it performs the task of caching and delivery of large objects in an efficient and cost-effective manner, without generating significant overheads for participating peers.

• Geomechanics and Engineering
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• 제31권5호
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• pp.439-452
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• 2022

A forecast of slope behavior during catastrophic events, such as earthquakes is crucial to recognize the risk of slope failure. This paper endeavors to eliminate the significant supposition of predefined slip surfaces in the slope stability analysis, which questions the relevance of simple conventional methods under seismic conditions. To overcome such limitations, a methodology dependent on the slip line hypothesis, which permits an automatic generation of slip surfaces, is embraced to trace the extreme slope face under static and seismic conditions. The effect of earthquakes is considered using the pseudo-static approach. The current outcomes developed from a parametric study endorse a non-linear slope surface as the extreme profile, which is in accordance with the geomorphological aspect of slopes. The proposed methodology is compared with the finite element limit analysis to ensure credibility. Through the design charts obtained from the current investigation, the stability of slopes can be assessed under seismic conditions. It can be observed that the extreme slope profile demands a flat configuration to endure the condition of the limiting equilibrium at a higher level of seismicity. However, a concurrent enhancement in the shear strength of the slope medium suppresses this tendency by offering greater resistance to the seismic inertial forces induced in the medium. Unlike the traditional linear slopes, the extreme slope profiles mostly exhibit a steeper layout over a significant part of the slope height, thus ensuring a more optimized solution to the slope stability problem. Further, the susceptibility of the Longnan slope failure in the Huining-Wudu seismic belt is predicted using the current plasticity approach, which is found to be in close agreement with a case study reported in the literature. Finally, the concept of equivalent single or multi-tiered planar slopes is explored through an example problem, which exhibits the appropriateness of the proposed non-linear slope geometry under actual field conditions.

• The Korean Journal of Physiology and Pharmacology
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• 제28권4호
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• pp.323-333
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• 2024

Polychlorinated biphenyls (PCBs) were once used throughout various industries; however, because of their persistence in the environment, exposure remains a global threat to the environment and human health. The Kv1.3 and Kv1.5 channels have been implicated in the immunotoxicity and cardiotoxicity of PCBs, respectively. We determined whether 3,3',4,4'-tetrachlorobiphenyl (PCB77), a dioxin-like PCB, alters human Kv1.3 and Kv1.5 currents using the Xenopus oocyte expression system. Exposure to 10 nM PCB77 for 15 min enhanced the Kv1.3 current by approximately 30.6%, whereas PCB77 did not affect the Kv1.5 current at concentrations up to 10 nM. This increase in the Kv1.3 current was associated with slower activation and inactivation kinetics as well as right-shifting of the steady-state activation curve. Pretreatment with PCB77 significantly suppressed tumor necrosis factor-α and interleukin-10 production in lipopolysaccharide-stimulated Raw264.7 macrophages. Overall, these data suggest that acute exposure to trace concentrations of PCB77 impairs immune function, possibly by enhancing Kv1.3 currents.