• Proceedings of the Korean Magnestics Society Conference
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• 2002.12a
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• pp.132-133
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• 2002

자속밀도를 측정하기 위한 방법으로 Hall 효과; NMR, Fluxgate 등의 다양한 방법등을 사용하고 있다. 그러나 가장 많이 사용되는 방법이 Faraday 전자기 유도 법칙을 이용하여 자속밀도를 측정하는 방법이다. 이 경우 탐지코일에 유도되는 기전력이 자속의 시간 변화율에 비례하기 때문에 자속을 측정하기 위해서는 탐지코일에 유도되는 기전력을 적분을 하여야 한다. (중략)

• 한국데이터정보과학회:학술대회논문집
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• 2001.10a
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• pp.34-41
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• 2001

본 논문에서는 비재생보증을 갖는 수리 가능한 시스템에 대한 베이즈 관점에서의 최적의 교체정책을 제안한다. 비재생무료보증(non-renewing free-replacement warranty : NFRW)과 비재생비례보증(non-renewing pro-rata warranty : NPRW)의 두 가지 경우에 대하여 각각 기스템의 고장시간이 와이블분포일 때 베이즈 관점에서의 단위시간당 기대비용을 최소화하는 최적의 교체정책과 순응적 교체정책에 대하여 설명한다.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10c
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• pp.358-360
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• 2002

기존의 정적 부하균등화 기법들은 동적 객체의 내재된 부하와 서버득의 다양한 상태 변화에 따른 능동적 부하분배가 불가능하다. 이를 위해 각 서버에서 프로세스가 자원을 전유하는 비율에 따라 해당 서버의 부하량을 판단하는 새로운 부하할당 기법을 제안하였다. 각 서버의 더미 프로세스는 자신이 프로세서를 점유하는 시점마다 해당 서버의 ID만을 전달함으로써 부하에 따른 차등하게 비동기된 서버보고를 수행한다. 이를 통해 라 서버는 자신의 부하량에 비례하여 부하균등화 참여율을 조정하여 성능저하를 최소화하고 부하량 판단 정보로 활용한다. 결국 제안기법은 웹 서비스의 부하의 성향에 무관하게 지능적인 부하할당을 가능케 한다.

• Journal of KIISE:Information Networking
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• v.28 no.4
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• pp.477-488
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• 2001

In wireless networking environments, supporting guaranteed quality of service to mobile hosts is difficult due to the facts that wireless networks have limited bandwidth and mobile hosts frequently move in and out of cells. In spite of the characteristics of wireless communications, the quality of some types of services, i.e., real-time services, must be guaranteed at a certain level. When a mobile host moves into another cell, service rates for mobile hosts in wireless networks may be adjusted since wireless networks have limited bandwidths. In this paper, we propose two resource allocation algorithms in wireless mobile networks, using quality of service (QoS) specifications. For efficient use of resources of wireless networks, the proposed algorithms dynamically allocate rates of flows in proportion to QoS with limited resources.

• Tribology and Lubricants
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• v.25 no.6
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• pp.404-408
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• 2009

In this paper, the relationship between the material removal rate and the interfacial mechanical properties at particle-surface contact situation, which can be seen in an abrasive machining process using micro/nano-sized particles, was discussed. Friction and stiffnesses were measured experimentally on an atomic force microscope (AFM) by using colloidal probes which have a silica colloid particle in place of tip to simulate a particle-flat surface contact in an abrasive machining process. From the experimental investigation and theoretical contact analysis, the interfacial contact properties such as lateral stiffness of contact, friction, the material removal rate were presented with respect to some of material surfaces and the relationship between the properties as well.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.7 no.4
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• pp.234-237
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• 1974

Electro-chemical aspects of stress corrosion on the mild steels when immersed in the $5\%\;H_2SO_4$ solution and charged with 100mV and 100mA were discussed. The main results of the experiment are follows; 1. The weight loss by corrosion was concerned with the applied stress. and the larger the applied stress, the greater the weight loss. 2. Reduction of corrosion stress was a factor of inverse proportion to the applied stress. 3. Corrosion began at first on the parts of impurities concentrated and the grain boundaries, and gradually developed and spreaded out. 4. The materials of unsteady structure deformed of space lattice by the high stress or work-hardening showed less reduction of corrosion stress.

• Journal of the Korea Institute of Building Construction
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• v.17 no.6
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• pp.507-515
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• 2017

This study is to develop a high quality lightweight foamed concrete that can be applied in the field using EXFG by cracking reducing agent combined with FGD and ALS. First, to increase the volume of foam, the flow and density of the mixture was increased and decreased, respectively. At this time, the effect of substitution ratio of EXFG on fluidity was negligible. The fraction of foam was the highest at EXFG 1%, and the settlement was found to be prevented by the expansion reaction at EXFG 1%. At this time, the ratio of foam was 65%. In the compressive strength, the strengths were similar or decreased when the substitution ratio of EXFG was more than 1%. The apparent density satisfied the KS 0.5 type at the bubble contents was 65%. In case of EXFG substitution, dry shrinkage was decreased by about 10%. As the substitution ratio of EXFG increased, the thermal conductivity increased proportionally.

• Korean Journal of Environment and Ecology
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• v.15 no.1
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• pp.57-68
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• 2001

해안지역의 녹화 및 조경용으로 유용한 내염성 식물자원임과 동시에 서식지가 급격히 감소하고 있는 순기비나무를 대상으로 하여 생장특성과 번식방법을 규명하기 위한 연구를 수행하였던 바, 그 결과를 요약하면 다음과 같다. 1. 줄기의 생장형태는 포복줄기와 직립줄기가동시에 생장하고, 5개 주요 군락지에 직립줄기의 길이는 평균 46.6cm 이고, 포복경의 초대 길이는 7.6cm에 달하였다. 2. 종작발아율은 황적색의 무처리 종자와 $GA_3$처리 종자에서 71.0~72.3%로 가장 높았으나, 두 처리군사이에는 발아율의 차이가 없었다. 종피현화를 목적으로 한 황산처리는 오히려 종자의 발아를 억제하였다. 3. 종피 색깔이 황적생인 종자는 흑갈색 종자에 비해 평균 21.1%(13~30%)발아율이 높았다. 실득모율은 30% 미만으로 아주 낮았으나 흑갈색 종자에 비해 황적색 종가자 약 2배 높았다. 또한 $LD_{50}$은 황적색 종자가 흑갈색 종자보다 10~20일 짧았다. 4. 종피 색깔과 화학처리가 같은 조건에서 기건저장한 종자와 노천매장한 종자사이에는 발아율, 식득묘율, $LD_{50}$등의 차이가 없었다. 5. 기건저장한 황적색 종자가 바다모래에서 30.3%의 발아율과 10.1%의 실득모율을 나타냈으나, 갯벌흙에서는 전혀 발아되지 않았다. 6. 삽목번식의 경우 추삽에서 발근육은 녹지삽이 가장 높았고, 다음이 반지숙삽, 숙지삽의 순이었다. 발근율이 가장 높은 것은 NAA 200ppm+sucrose 2%를 처리한 녹지로서 96.7%의 발근율을 나타내었다. 발근수는 전반적으로발근율에 비례하는 경향이었다. 7. 하삽에서 NAA 200ppm+sucrose 2%를 처리한 녹지, 반숙지, 숙지의 토양별 발근율은 vermiculite+ perlite(1:1)와 마사토에서는 81.1~87.8%로 높았고, 모래와 해상에서 48.9~77.8%로 낮았다.

• Composites Research
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• v.34 no.6
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• pp.387-393
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• 2021

This paper investigated the electrical properties of multiwall carbon nanotube reinforced polydimethylsiloxane (CNT-PDMS) strain sensors with copper electrodes on the wet-etched surface. MWCNT-PDMS strain sensors were fabricated according to the wt% of MWCNT. Surfaces on the electrode area were wet-etched with various etching duration and silver epoxy adhesives were spread on the wet-etched surface. Finally, we attached the copper electrodes to the MWCNT-PMDS strain sensors. We checked the electric conductivities by the two-probe method and sensing characteristics under the cyclic loading. We observed the electric conductivity of MWCNT-PDMS strain sensors increased sharply and the scattering of the measured data decreased when the surface of the electrode area was wet-etched. Initial resistances of MWCNT-PDMS strain sensors were inversely proportion to wt% of MWCNT and the etching duration. However, the resistance changing rates under 30% strain increased as wt% of MWCNT and the etching duration increased. Decreasing rate of the electric resistance change after 100 repetitions was smaller when wt% of MWCNT was larger and the etching duration was short. This was due to the low initial resistance of the MWCNT-PMDS strain sensors by the wet-etching.

• The Journal of Korean Academy of Prosthodontics
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• v.55 no.3
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• pp.272-278
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• 2017

Purpose: The aim of the present prospective clinical study was to assess the cumulative survival rate (CSR) of Neobiotech implants restored with fixed partial prosthesis in relation to its potential risk factors. Materials and methods: Thirty six partially edentulous patients received Neobiotech implants and implant supported fixed partial prosthesis at Korea University Guro Hospital Dental Center from November 2009 until November 2011. The observation period was set from the implant placement and the last clinical visit until December 2015. Implant survival rate was determined using the Kaplan-Meier method. The relationship between implant survival rate and the potential risk factors were analysed using the multi Cox proportional analysis (P<.05). Results: A total of 69 implants were placed in 36 patients after a mean observation period of 45.9 months. Two out of 69 implants failed before loading, yielding a 5-year cumulative survival rate of 97.1%. The maxillary implants have a lesser CSR than the mandibular implants based on log rank test analysis (maxilla=91.3%; mandible=100% P<.05). However, the multi Cox proportional analysis showed that implant location has no significant correlation with implant failure (P>.05). Conclusion: Neobiotech implants showed predictable results with a 5 year cumulative survival rate of 97.1%.