• 자원환경지질
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• 제32권3호
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• pp.307-315
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• 1999

Four organic polymers were mixed with mothmorillonite. Two cationic polymers a hi로 molecular weight polyacrylamide (494C) and a low molecular weight polymer (587C).Two anionic polymers include a high molecular weight polymer (aerotil). Each clay supension series were allowed to stand for 24 hours and were centrifuged, and the clay plugs were washed and dried. The dried samples investigated by XRD, IR and CEC measurement. The suspended clay containing anionic polymers was not flocculated at any concentratuons of polymer. But the suspendions containing two cationic polymers were rapidly flocculated at almost all concentrations. the d(001) spacings of Na-montmorillonite after being with cationic polymer 587C show about 15$\AA$ suggesting the polymers may have entered the interlayer spaces. The polymer 494C-treated sample produced double peaks of about 12 and 15$\AA$ in XRD. It indicates that the high molecular weight polymer. And cationic polymer 494C may be adsorbed mainy on the outside surface of clay, and some polymers may peretrate into olny interlayers in the margin of montmorillonite particles because of its high molecular weught. CEC of polumer 587-treated sample was reduecd mmarkedly suggesting polymer blocks CEC sites. The d(001) spacings of Ca-montmorillonite after being treated with cationic polymers show about 15$\AA$ suggesting that the interlayer spaces have not been expanded. In the experiment using a dilute Ca-bearing solution, the suspended caly containinf anionic polymers was flocculated. The results indicate that the flocculation behavior of montmorillonite-polymer supension depends on not only polymer properties such as concentration, electric charge and molecular weight but also compositions of solvent.

• 한국군사과학기술학회지
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• 제2권2호
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• pp.52-60
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• 1999

By implementing the Systems Engineering process for the aircraft preliminary design, functional analysis study is performed, hence Functional Interface Data Flow(FIDF) and Functional Flow Block Diagram(FFBD) are generated. Based on FIDF and FFBD, allocable and non-allocable design/performance/RM＆S requirements are allocated to the appropriate levels. Weight and cost tracking and design margin management methodologies are studied and implemented for the balanced aircraft design.

• 한국해양공학회지
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• 제33권6호
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• pp.495-503
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• 2019

Approximately 90,000 ships are registered in South Korea, and about 80,000 of these ships are used in domestic shipping. Among these, 84% are small ships, such as a fishing vessels that weigh less than 20 tons and are made mostly of an FRP (Fiber Reinforced Plastics). When this fact is taken into account, the greenhouse gas emissions that are released per ton of a composite vessel are sizeable. In this study, the laminated structures of an FRP fishing vessel, many of which currently are being built in Korea, were analyzed by ISO (International Organization for Standardization) and international design rules, and the structures of the hulls are lightweight with optimum glass fiber mass content as determined by the laminate weight minimization algorithm. As a result, it was confirmed that the laminations of the vessels in accordance with the Korean rule could have 6.4% to approximately 11% more design margin compared to the requirements of ISO and other international rules. And the case study of the application of the laminate weight minimization algorithm showed the possibility of reducing the weight of the hull bottom plating by as much as about 19.32% and by as much as about 18.06% in the overall structure.

• Smart Structures and Systems
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• 제25권6호
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• pp.719-732
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• 2020

Real-time hybrid simulation (RTHS) which combines physical experiment with numerical simulation is an advanced method to investigate dynamic responses of structures subjected to earthquake excitation. The desired displacement computed from the numerical substructure is applied to the experimental substructure by a servo-hydraulic actuator in real time. However, the magnitude decay and phase delay resulted from the dynamics of the servo-hydraulic system affect the accuracy and stability of a RTHS. In this study, a robust stability analysis procedure for a general single-degree-of-freedom structure is proposed which considers the uncertainty of servo-hydraulic system dynamics. For discussion purposes, the experimental substructure is a portion of the entire structure in terms of a ratio of stiffness, mass, and damping, respectively. The dynamics of the servo-hydraulic system is represented by a multiplicative uncertainty model which is based on a nominal system and a weight function. The nominal system can be obtained by conducting system identification prior to the RTHS. A first-order weight function formulation is proposed which needs to cover the worst possible uncertainty envelope over the frequency range of interest. Then, the Nyquist plot of the perturbed system is adopted to determine the robust stability margin of the RTHS. In addition, three common delay compensation methods are applied to the RTHS loop to investigate the effect of delay compensation on the robust stability. Numerical simulation and experimental validation results indicate that the proposed procedure is able to obtain a robust stability margin in terms of mass, damping, and stiffness ratio which provides a simple and conservative approach to assess the stability of a RTHS before it is conducted.

• 정보보호학회논문지
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• 제32권6호
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• pp.1045-1057
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• 2022

최근 양자 내성 암호 표준화 사업을 진행 중인 미국의 국립표준기술연구소는 표준화가 확정된 4개의 알고리즘을 발표하였다. 본 논문에서는 PKE/KEM 분야에서 표준화가 확정된 CRYSTALS-KYBER 알고리즘의 복호화 과정 중 비프로파일링 기반 전력 분석 공격인 CPA(Correlation Power Analysis)와 DDLA(Differential Deep Learning Analysis)에 의해 개인 키가 노출될 수 있음을 보이고자 한다. 실험 결과 개인 키의 일차 다항식 계수복구에 성공하였으며, 특히 DDLA에서는 중간 값의 해밍 웨이트(Hamming Weight)를 라벨로 사용하는 모델에서 평가 기법인 NMM(Normalized Maximum Margin)의 값이 13.0으로 가장 높은 값을 가져 개인 키를 복구할 수 있는 것을 확인하였다. 또한, 복호화 과정 중 암호문을 랜덤하게 분할하고 계수별 곱셈 연산의 시작 지점을 랜덤화하는 방어 기법을 적용하면 상기한 공격을 방어하는 것을 확인하였다.

• Composites Research
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• 제26권1호
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• pp.29-35
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• 2013

복합재료 샌드위치 구조는 굽힘 강성을 향상시키고 복합재 적층판에 비해 30% 이상의 무게를 절감할 수 있다. 그러나 일반 금속에 비해 제작과정에서 발생되는 재료물성의 불확실성이 많이 내재되어 있으므로 신뢰성 기반 확률론적 설계방법이 요구된다. 본 논문에서는 안전계수를 이용한 고전적인 설계 방법이 구조물의 안전을 보장하지 않는다는 확률론적 증거를 제시하기 위하여 단순화된 복합재 샌드위치 동체에 대해 PMS(Probabilistic Margin of Safety)를 계산하였다. 이 과정에서 CMCS(Crude Monte-Carlo Simulation)에 의해 계산된 확률밀도함수를 이용하였다. 더 나아가 신뢰성 기반 최적설계를 수행하고 효율적인 계산을 위해 RBDO-MPDF(RBDO by Moving PDF) 방법을 제시하였다. 본 논문의 결과는 구조물의 신뢰성을 보장하기 위한 개선된 설계 방법과 효율적인 신뢰성 기반 최적설계 방법 연구에 유용할 것이다.

• 한국지형학회지
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• 제15권2호
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• pp.25-35
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• 2008

2006년 7월의 태풍 에위니아와 빌리스에 의한 집중호우로 인해 급경사의 사면이 많고 기복이 큰 강원도 지역에서 토사재해가 크게 발생하였다. 특히 한계령을 관통하는 국도 44호선 도로는 단층선곡을 따라 건설되어 토사재해의 가능성이 가장 높은 편에 속하는 지역이다. 오색천 주변에서 발생한 토석류는 호우에 의해 공극수압이 상승하고 사면부의 무게가 증가하면서 발생한 능선부와 산정부의 산사태에 의해 촉발되었다. 또한 기존의 붕적물 또는 계안퇴적물에 가해진 하천의 압력에 의해서도 특히 공격사면 쪽에서 많은 토석류가 발생하였다. 하천의 상류부에서는 도로주변의 급경사의 절개지와 사면부의 얇은 풍화층에서 산사태가 발생한 반면, 중류부에서는 계류부의 토석류가 도로변의 배수구조물 용량을 초과하여 월류가 발생하여 도로와 교량이 파괴되었고, 하류부에서는 하천범람에 의한 계류부 양안의 침식과 토석류에 의한 피해가 가장 크게 나타났다. 하류부 퇴적층의 경우 토석류가 일회성이 아니라 과거 수차례 더 발생했었다는 사실을 보여주고 있다. 따라서 기후변화와 관련하여 호우의 빈도와 강도가 높아질 것으로 예측되는 만큼 추후 토사재해와 관련된 정보시스템의 구축과 관리시스템에 대한 연구가 절실히 요구된다.

• 대한본초학회지
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• 제25권3호
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• pp.43-51
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• 2010

Objectives : We investigated the repeated-dose toxicity of Wenpitang-Hab-Wulingsan(WHW), a Korean traditional medicine prescribed with twelve herbs, which has been used for the treatment of renal disease. Methods : WHW extract prepared by GLP company. WHW was supplemented by gavage at 0, 100, 500 and 1000 mg/kg/day for 13-week consecutive days. We recorded the clinical signs of toxicity, body weight, organ weights, hematology, gross and histological changes in target organs rats and clinical chemistry analysis for all rats. Results : WHW extract at all doses was shown no mortality or abnormal clinical signs in rats during at the observation period. Furthermore, there was no difference in body weight and food-take consumption, organ weight, gross pathological findings, and urine analysis among the groups of rats treated with different doses of WHW extract. The hematological analysis and clinical blood chemistry data were revealed no toxic effects from WHW-treated rats. Conclusions : The results suggest that WHW extract in rats is a wide margin of safety on a acute toxicity.

• Archives of Plastic Surgery
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• 제45권3호
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• pp.222-228
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• 2018

Background The most common surgical treatment for paralytic lagophthalmos is the placement of a weight implant in the upper eyelid; however, this technique confers the risks of implant visibility, implant extrusion, and entropion. In this study, we present a new technique of placing platinum weight implants between the levator aponeurosis and inner septum to decrease such complications. Methods A total of 37 patients with paralytic lagophthalmos were treated between March 2014 and January 2017 with platinum weight placement (mean follow-up, 520.1 days). After dissecting through the orbicularis oculi muscle, the tarsal plate and levator aponeurosis were exposed. The platinum weights (1.0-1.4 g) were fixed to the upper margin of the tarsal plate and placed underneath the orbital septum. Results Five patients could partially close their eye after surgery. The average distance between the upper eyelid and the lower eyelid when the eyes were closed was 1.12 mm. The rest of the patients were able to close their eye completely. Three patients patient developed allergic conjunctivitis after platinum weight insertion, which was managed with medication. None of the patients complained of discomfort in the upper eyelid after surgery. Visibility or extrusion of the implant were observed in three patients. Conclusions Postseptal weight placement is a safe and reproducible method in both primary and secondary upper eyelid surgery for patients with paralytic lagophthalmos. It is a feasible method for preventing implant visibility, implant exposure, and entropion. Moreover, platinum is a better implant material than gold because of its smaller size and greater thinness.

• 분석과학
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• 제9권1호
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• pp.1-12
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• 1996

열에 불안정하면서 -OH기를 함유하는 미지의 화합물은 LC/TSP/MS에서 [${MNH_4}^+$] 이온, [$MH^+$] 이온, 그리고 [$MH^+-OH$] 이온의 생성이 가능하며, 이들 이온의 m/z값의 차이가 17로서 같기 때문에 이들의 생성 정도에 따라 분자량 추정에 혼란이 일어날 수가 있었다. 따라서 다른 보완 가능한 실험결과가 요구되며 $CF_3COOD+NH_4OH$ 이온화 용액을 사용하여 그 유용성을 검토하였다. 또한 LC/TSP/MS에서 생성되는 토막이온들이 필라멘트의 전자살에 의해 생성되는 것인지 아니면 다른 어떤 생성기전이 존재하는지를 검토하였다.