• 한국철도학회:학술대회논문집
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• 한국철도학회 1998년도 추계학술대회 논문집
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• pp.47-53
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• 1998

Many kinds of methods have been developed to carry out transverse analysis of prestressed concrete(PSC) box girder bridges. However, most bridge engineers only use the simple frame model to analyze PSC box girder in transverse direction because of its simplicity and easy usage. But, this frame model has many problems such that it can't consider warping, distortion and longitudinal load distribution. In this study, the results from simple frame model and 3-dimensional shell model with UIC load are compared to show its validity. The results from frame model are slightly larger than those of shell model in symmetric loading case. But, positive bending moment of top slab is larger in shell model than frame model in case subject to anti-symmetric loading. It shows that simple frame model can't always give conservative results, so a practical tool whose treatment is easy and whose product is reliable shall be developed as soon as possible.

• Restorative Dentistry and Endodontics
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• 제20권2호
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• pp.432-461
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• 1995

The basic principles in the design of Class II amalgam cavity preparations have been modified but not changed in essence over the last 90 years. The early essential principle was "extension for prevention". Most of the modifications have served to reduce the extent of preparation and, thus, increase the conservation of sound tooth structure. A more recent concept relating to conservative Class II cavity preparations involves elimination of occlusal preparation if no carious lesion exists in this area. To evaluate the ideal ClassII cavity preparation design, if carious lesion exists only in the interproximal area, three cavity design conditions were studied: Rodda's conventional cavity, simple proximal box cavity and proximal box cavity with retention grooves. In this study, MO amalgam cavity was prepared on maxillary first premolar. Three dimensional finite element models were made by serial photographic method. Linear, eight and six-nodal, isoparametric brick elements were used for the three dimensional finite element model. The periodontal ligament and alveolar bone surrounding the tooth were excluded in these models. Three types model(B option, Gap option and R option model) were developed. B option model was assumed perfect bonding between the restoration and cavty wall. Gap option model(Gap distance: $2{\mu}m$) was assumed the possibility of play at the interface simulated the lack of real bonding between the amalgam and cavity wall (enamel and dentin). R option model was assumed non-connection between the restoration and cavty wall. A load of 500N was applied vertically at the first node from the lingual slope of the buccal cusp tip. This study analysed the displacement, 1 and 2 direction normal stress and strain with FEM software ABAQUS Version 5.2 and hardware IRIS 4D/310 VGX Work-station. The results were as followed. 1. Rodda's cavity form model showed greater amount of displacement with other two models. 2. The stress and strain were increased on the distal marginal ridge and buccopulpal line angle in Rodda's cavity form model. 3. The stress and strain were increased on the central groove and a part of distal marginal ridge in simple proximal box model and proximal box model with retention grooves. 4. With Gap option, Rodda's cavity form model showed the greatest amount of the stress on distal marginal ridge followed by proximal box model with retention grooves and simple proximal box model in descending order. 5. With Gap option, simple proximal box model showed greater amount of stress on the central groove with proximal box model with retention grooves. 6. Retention grooves in the proximal box played the role of supporting the restorations opposing to loads.

• 한국대기환경학회지
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• 제21권3호
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• pp.377-397
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• 2005

A new box model is proposed to describe the dynamic trend of the spatially averaged concentrations of pollutants over a large urban area such as metropolitan Seoul. Being averaged temporally and spatially over a thresh-hold scales, the dynamics of the pollutant concentration becomes simple enough that the governing equation can be expressed in an explicit algebraic form as a function of several meteorological factors and the pollutant emission rate. The single most important meteorological factor is the wind speed dominating the daily variations of the pollutant concentrations. Given the meteorological data from the surface station in the metropolitan Seoul, the model concentration shows excellent agreement with observations from January 1, 1990 to December 31, 2000: the modeling uncertainty, for example, of $NO_2$ concentrations, defined as mean differences between the model concentrations and observations is $16\%$ of the model concentrations. Even for $PM_{10}$ of which secondary sources are considered to be very important and simple box model is irrelevant to, the model performance turns out good, modeling uncertainty being about $32\%$.

• 대한전자공학회논문지
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• 제26권12호
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• pp.2001-2009
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• 1989

This study suggests the use of fuzzy model in the semiconductor devices modeling as a black box approach. When membership functions of fuzzy sets used in a fuzzy model are simple piecewise-linear functions, the fuzzy model can be reresented in a simple equation. To show that the fuzzy model can be very realistic and simple when used in semiconductor devices modeling, we construct fuzzy models for bipolar transistor, MOSFET and GaAs FET, and compare those with canonical piecewise-linear models.

• 한국해양환경ㆍ에너지학회지
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• 제14권4호
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• pp.257-263
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• 2011

SBM을 이용하여 2006년 가막만의 담수, 염분, 영양염 등 물질 수지를 산정하였다. 담수유출량은 $-174.2{\sim}72.5{\times}10^3m^3/day$로 나타났으며 개방경계에서의 해수 교환에 의한 mixing volume은 $-2.4{\times}10^7\sim4.9{\times}10^7m^3/day$로 만 내외의 염분차이에 의해 크게 좌우 받았다. 육상기인 DIP와 DIN의 유입 flux의 범위는 397.0~1158 mole/day 및 1750~8328 mole/day의 범위로 다른 지역에 비해 낮았다. DIP의 소실 또는 생성은 물수지의 변동에 의해 크게 좌우 되는 특징을 보였으며, 또한, 물질체류시간에 의해 물질수지가 크게 좌우되어 NEM도 크게 달라지는 결과를 보였다.

• 대한기계학회논문집
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• 제17권11호
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• pp.2704-2710
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• 1993

A simple and straightforward method is introduced for developing continuum beam-rod model of a box-beam typed aircraft wing with composite layered skin based on "energy equivalence." The equivalent continuum structral properties are obtained from the direct comparison of the reduced stiffness and mass matrices for box-beam typed wing with those for continuum beam-rod model. The stiffness and mass matrices are all represented in terms of the continuum degrees-of freedom defined in this paper. The finite-element method. The advantage of the present continuum method is to give every continuum structural properties including all possible coupling terms which represent the couplings between different deformations. To evaluate the continuum method developed in this paper, free vibration analyses for both continuum beam-rod and box-beam are conducted. Numerical tests show that the present continuum method gives very reliable structural and dynamic properties compared to the results by the conventional finite-element analysis. analysis.

• 한국정보기술학회 영문논문지
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• 제9권2호
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• pp.115-123
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• 2019

White-box cryptography is an implementation technique in order to protect secret keys of cryptographic algorithms in the white-box attack model, which is the setting that an adversary has full access to the implementation of the cryptographic algorithm and full control over their execution. This concept was introduced in 2002 by Chow et al., and since then, there have been many proposals for secure implementations. While there have been many approaches to construct a secure white-box implementation for the ciphers with SPN structures, there was no notable result about the white-box implementation for the block ciphers with Feistel structure after white-box DES implementation was broken. In this paper, we propose a secure white-box implementation for a block cipher SEED with Feistel structure, which can prevent the previous known attacks for white-box implementations. Our proposal is simple and practical: it is performed by only 3,376 table lookups during each execution and the total size of tables is 762.5 KB.

• International Journal of Naval Architecture and Ocean Engineering
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• 제9권6호
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• pp.705-719
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• 2017

Progressive Collapse Method (PCM) has been broadly applied to predict moment-carrying capacity of a hull girder, however accuracy of PCM has not been much studied. Accuracy of PCM is known to be dependent on how Load-Shortening and -Elongation (LSE) curve of a structural units are well predicted. This paper presents a new procedure to determine LSE datum based on box girder Finite Element Analyses (FEAs) instead of using finite element model of stiffened panels. To verify reliability of FEA results, the simple box girder collapse test results are compared with FEA results of same box girders. It reveals one frame-based box girder model is sufficiently accurate in terms of ultimate strengths of the box girders. After extracting LSE data from the box girders, PCM-based moment-carrying capacities are compared with those from FEAs of the box girders. PCM results are found to be equivalent to FEAs in terms of moment-carrying capacity if accurate LSE data are secured. The new procedure is applied to well-known 1/3 scaled frigate full section. Very excellent moment-carrying capacity of frigate hull section is obtained from PCM with LSE data from box girder FEAs.

• 정보보호학회논문지
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• 제32권5호
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• pp.817-826
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• 2022

AI 기술이 여러 분야에 성공적으로 도입되는 추세이며, 서비스로 환경에 배포된 모델들은 지적 재산권과 데이터를 보호하기 위해 모델의 정보를 노출시키지 않는 블랙 박스 상태로 배포된다. 블랙 박스 환경에서 공격자들은 모델 출력을 이용해 학습에 쓰인 데이터나 파라미터를 훔치려고 한다. 본 논문은 딥러닝 모델을 대상으로 모델 종류에 대한 정보를 추론하는 공격이 없다는 점에서 착안하여, 모델의 구성 레이어 정보를 직접 알아내기 위해 모델의 종류를 추론하는 공격 방법을 제안한다. MNIST 데이터셋으로 학습된 ResNet, VGGNet, AlexNet과 간단한 컨볼루션 신경망 모델까지 네 가지 모델의 그레이 박스 및 블랙 박스 환경에서의 출력값을 이용해 모델의 종류가 추론될 수 있다는 것을 보였다. 또한 본 논문이 제안하는 방식인 대소 관계 피쳐를 딥러닝 모델에 함께 학습시킨 경우 블랙 박스 환경에서 약 83%의 정확도로 모델의 종류를 추론했으며, 그 결과를 통해 공격자에게 확률 벡터가 아닌 제한된 정보만 제공되는 상황에서도 모델 종류가 추론될 수 있음을 보였다.

• 대한전자공학회논문지
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• 제21권4호
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• pp.58-64
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• 1984

이온주입형 E-IGFET에서 이온주입층내 불순물 profile을 임의의 형태로 가정하였으며, 가정한 불순물 profile을 이용하여 threshold 전압에 대한 간단한 model을 유도하였다. 유도한 model을 이용하여 Gaus-sian-profile일 때의 threshold 전압치를 구하였고, 실제의 측정 data와 비교하였을 때 일치함을 확인할 수 있었다. 더불어, box-profile일 때의 threshold 전압치의 오차를 계산해 보았다. 또한, substrate-bias에 의한 threshold 전압의 변화를 simulation하였으며. 계산과정에서 이온주입층의 깊이 D를 구하는 새로운 방법을 제시하였다.