• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2001.12a
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• pp.121-124
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• 2001

충돌회피 시스템은 선박의 안전 항해에 중요한 역할을 한다. 충돌회피 시스템은 선박이 장애물을 만났을 때 영역전문가인 항해사를 대신하여 피항 행위를 하도륵 지시하는 시스템으로 자선에서 이루어지는 해상 장애물들에 대한 피항 시 그 판단 기준을 각 장애물에 대한 충돌위험도에 둔다. 따라서 본 연구에서는 선박의 충돌회피 시스템의 보다 안전한 충돌회피를 도모하기 위해 충돌회피를 위한 충돌위험도 결정 시스템을 제안한다. 충돌위험도 결정 시스템은 장애물 모델링과 장애물의 충돌위험도 결정의 두 부분으로 구성된다. 장애물 모델링은 선박의 센서에서 나오는 저수준의 자료를 지능형 선박의 타 시스템에서 이용하기 쉽도록 구하는 과정이다. 충돌위험도 결정 시스템의 출력으로 산출되는 충돌위험도는 충돌회피 시스템의 피항 행위 결정에 정보로 사용된다. 본 연구에서는 DCPA와 TCPA를 이용한 기존의 기법에 VCD의 개념을 추가한 새로운 충돌위험도 결정 기법을 제안한다. 입력변수가 되는 DCPA, TCPA, VCD의 퍼지 소속함수를 산출하고 이를 기반으로 퍼지 추론을 이용하여 세부적인 충돌위험도를 결정한다. 본 연구에서 제안하는 기법은 기존의 DCPA와 TCPA만으로 충돌위험도를 결정한 경우보다 상세한 충돌위험도 결정이 가능하다는 장점과 국제해상충돌예방규칙의 내용이 적용되었다는 장점을 지닌다. 제안된 기법은 DCPA와 TCPA 만으로 충돌위험도를 결정한 기법과 비교.평가하여 성능을 검증한다.

• Journal of Korea Ship Safrty Technology Authority
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• s.35
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• pp.41-51
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• 2013

선박 고속화와 해양레저선박에 대한 관심 증대로 쌍동형 선체건조가 증가하고 있으며 일반적으로 쌍동형 선체는 복원성, 내항성능 및 저항추진 등에서 단동형 선체보다 고속선형 및 갑판활용에 적합하다고 알려져 있다. 하지만, 쌍동형 선체는 갑판 상에서 두 개의 선체를 동체로 결합시킨 선체로서 운동 시 부체 간 공진현상이 수반된 자유표면 거동과 유체력이 발생할 수가 있다. 따라서, 이 논문에서는 이런 공진현상을 감쇠시킬 수 있는 방안을 모색하여 합리적인 쌍동형 선체의 운동응답특성과 동유체력을 산출하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.2
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• pp.417-426
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• 2015

The representative design elements of the road geometric structure are longitudinal slope, horizontal curve radius, super elevation, and transition curve. According to the function of a road, the design standards of these elements is applied by diverse combinations of them. This study divided expressway into homogeneous segments based on longitudinal slope and horizontal curve radius. And then, data required for analysis were matched to each segment, and the safety performance function was built by using the established data. crash modification factors which can explain traffic accident exposure rate were calculated. When the threshold value of horizontal curve radius R=1,000 m was set to 1.0, the crash modification factors at R=300 m was calculated as 1.33, which means that the accident exposure rate is increased by 33%. When the threshold value of the longitudinal slope 0% was set to 1.0, the crash modification factors demonstrated that the accident exposure rate decreases on the upward slope and the accident exposure rate increases on the downward slope. The results of this study can be used as basic information in the design of expressway geometries during the improvement or the construction of expressways.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.6
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• pp.746-751
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• 2014

In this paper, ship performance prediction solver was developed using open source computational fluid dynamics (CFD) libraries. The mass- and momentum-conservation equations and turbulent model with a wall function for the turbulent closer were considered. The volume fraction transport equation with a high-resolution interface capturing scheme were selected for free-surface simulation. The predicted wave pattern around KRISO container ship (KCS) using developed program showed good agreement against existing experimental data. For the revolution of a propeller in the propulsive test, general grid interface (GGI) library was used. The predicted propulsive performance showed 7 % difference against experimental data. Two-phase mixture model was developed to simulate a cavitation and applied to a propeller. The sheet cavitation on the propeller was predicted well. From results, the potential of the numerical tank developed by open source libraries was verified by applying it to KCS.

• Journal of the Korea Society of Computer and Information
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• v.17 no.1
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• pp.53-60
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• 2012

In this paper, we propose a framework which supports the simple development cycle based on Distributed System using IPO(Input-Process-Output) model. In our proposed framework, once a single class with Input, Process and Output functions is developed, it can be executed like a single application in both presentation layer and middle layer of a distributed system. Our proposed Framework removes dependency on distributed system and makes development cycle decreased from Develop-Build-Deploy-Test cycle to Develop-Test cycle when application programs is developed. The verification of productivity and performance is performed by comparing our Framework with distributed system or lightweight Framework. The results show high productivity due to the considerable amount of reduction in lines of source code and reduction in dependency on distributed system, and show stabler performance than lightweight framework.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.4
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• pp.14-25
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• 2018

In recent years, it has become technically easier to explain factors related with traffic accidents in the Big Data era. Therefore, it is necessary to apply the latest analysis techniques to analyze the traffic accident data and to seek for new findings. The purpose of this study is to compare the predictive performance of the negative binomial regression model and the deep learning method developed in this study to predict the frequency of traffic accidents in expressways. As a result, the MOEs of the deep learning model are somewhat superior to those of the negative binomial regression model in terms of prediction performance. However, using a deep learning model could increase the predictive reliability. However, it is easy to add other independent variables when using deep learning, and it can be expected to increase the predictive reliability even if the model structure is changed.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.7
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• pp.958-963
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• 2023

Lately, there has been increasing research on the prediction of motion performance using artificial intelligence for the safe design and operation of ships. However, compared to conventional ships, research on small fishing boats is insufficient. In this paper, we propose a model that estimates the motion response essential for calculating the motion performance of small fishing boats using a deep neural network. Hydrodynamic analysis was conducted on 15 small fishing boats, and a database was established. Environmental conditions and main particulars were applied as input data, and the response amplitude operators were utilized as the output data. The motion response predicted by the trained deep neural network model showed similar trends to the hydrodynamic analysis results. The results showed that the high-frequency motion responses were predicted well with a low error. Based on this study, we plan to extend existing research by incorporating the hull shape characteristics of fishing boats into a deep neural network model.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.4
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• pp.467-474
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• 2018

The purpose of this study is related to automatic hull-form design for ships operating at two speeds. Research was conducted using a series 60 ($C_B=0.6$) ship as a target, which has the most basic ship hull-form. Hull-form development was pursued from the viewpoint of improving resistance performance. In particular, automatic hull-form design for a ship was performed to improve wave resistance, which is closely related to hull-forms. For this purpose, we developed automatic hull-form design software for ships by combining an optimization technique, resistance prediction technique and hull-form modification technique, appling the software developed to a target ship. A sequential quadratic programming method was used for optimization, and a potential-based panel method was used to predict resistance performance. A Gaussian-type modification function was developed and applied to change the ship hull-form. The software developed was used to design a target ship operating at two different speeds, and the performance of the resulting optimized hull was compared with the results of the original hull. In order to verify the validity of the program developed, experimental results obtained in model tests were compared with calculated values by numerical analysis.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.6
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• pp.1295-1305
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• 2017

There is SEED cryptosystem in domestic block cipher standard. This code was drafted by the Korea Information Security Agency (KISA) in October 1998 and underwent a public verification process in December of the same year, which resulted in the final amendment to improve safety and performance. Unlike DES, it is a 128-bit block cipher that has been passed through various processes and established in 2005 as an international standard. It is a block cipher with a pastel structure like DES, but the input bit block has been increased to 128 bits, double DES. In this paper, first, we introduce the general algorithm of SEED cryptosystem and analyzed mathematically generating principle of key-value which is used in F-function. Secondly, we developed a table that calculates the exponent of the primitive element ${\alpha}$ corresponding to the 8-bit input value of the S-function and finally analyzed calculating principle of S-function designed in G-function through the new theorem and example. Through this course, we hope that it is to be suggest the ideas and background theory needed in developing new cryptosystem to cover the weakness of SEED cryptosystem.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.6
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• pp.57-68
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• 2009

Recently, damage scale of human-induced disaster is sharply increased but its occurrences and damages are so uncertain that it is hard to construct a resonable response & mitigation plan for infrastructures. Therefore, the needs for a advanced risk management technique based on a probabilistic and stochastic risk evaluation theory is increased. In this study, these evaluation methods were investigated and a advanced disaster risk evaluation method, which is based on the probabilistic or stochastic risk assessment theory and also is a quantitative evaluation technique, was suggested. With this method, the safety changes as the result of fire damage management for recent 40 years was analyzed. And the result was compared with that of Japan. Through the consilience of the traditional risk assessment method and this method, a stochastical estimation technique for the uncertainty of future disaster's damage could support a cost-effective information for a resonable decision making on disaster mitigation.