• Bulletin of the Society of Naval Architects of Korea
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• v.42 no.1 s.143
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• pp.47-50
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• 2005

최근 Containership의 대형화가 진행됨에 따라 선수부의 선형 변화에 따른 선체의 구조부재 배치에 상당한 변화가 필요하게 되었다. 선수구조는 선형 변화 특히, Bow Flare Angle의 작은 변화에도 Bow Impact Pressure가 상당히 민감하게 반응함으로 외력에 의한 구조 배치 변경 및 추가적인 구조보강에 대한 여유를 갖고 설계를 진행할 필요성이 요구된다. 따라서, 본 논문에서는 선수부의 선형 및 구조 배치 변화에 따른 강도 평가를 구조해석을 통하여 구조 안정성을 검증하였으며, 구조 안정성 평가 절차 및 구조 해석 결과에 따른 구조 최적 배치 및 구조개선 사항을 간략히 정리하였다.

• Bulletin of the Society of Naval Architects of Korea
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• v.19 no.4
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• pp.1-10
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• 1982

An experimental investigation on the energy absorption of two staged combined structures is presented, which deals with the plastic collapse test as a series of research on soft bow structure involved in a ship collision. The principle of arithmetic superposition of energy absorption is derived upon experimental analysis and based upon the characteristics of the energy absorptions of component structures. This relationship is related to the further approach toward the design of soft bow.

• Journal of Korean Ophthalmic Optics Society
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• v.11 no.3
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• pp.241-247
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• 2006

Purpose : To define the distribution of normal corneal topographic patterns of Korean college students and compare them with previously published western data, Bogan et al's study. Methods : Computerized corneal topography was performed 220eyes normal subjects using CTK-922(Topography, swiss made). Mean age of the subjects was 23.2 yr.(range 19 to 57 yr.). The color-coded videokeratographs were classified by a masked observer according to the Bogan et al's classification such as round, oval, symmetric bow tie, asymmetric bow tie, and irregular. Results: The results revealed 57 eyes(25.9%) had round, 14 (6.4%) oval , 41(18.6%)symmetric bow tie, 78(35.5%) asymmetric bow tie, and 30(13.6%) irregular pattern. Conclusions : Our results of topographic patterns show the tendency of more irregular and less round topographic pattern in Korean college students, as compared to that of western adults.

• Journal of Digital Contents Society
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• v.14 no.4
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• pp.581-587
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• 2013

In this paper, we propose a method of sentiment classification which uses Levenshtein distance. We generate BOW(Bag-Of-Word) applying Levenshtein daistance in sentiment features and used it as the training set. Then the machine learning algorithms we used were SVMs(Support Vector Machines) and NB(Naive Bayes). As the data set, we gather 2,385 reviews of movies from an online movie community (Daum movie service). From the collected reviews, we pick sentiment words up manually and sorted 778 words. In the experiment, we perform the machine learning using previously generated BOW which was applied Levenshtein distance in sentiment words and then we evaluate the performance of classifier by a method, 10-fold-cross validation. As the result of evaluation, we got 85.46% using Multinomial Naive Bayes as the accuracy when the Levenshtein distance was 3. According to the result of the experiment, we proved that it is less affected to performance of the classification in spelling errors in documents.

• Journal of the Society of Naval Architects of Korea
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• v.51 no.6
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• pp.459-479
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• 2014

This paper considers experimental and numerical studies on added resistance in waves. As the numerical methods, three different methods, strip method, Rankine panel method and Cartesian-grid method, are applied. The computational results of vertical motion response and added resistance are compared with the experimental data of Series 60($C_B=0.8$) hull, S175 containership and KVLCC2 hull. To investigate the influence of above-still water hull form, a Rankine panel method is extended to two nonlinear methods: weakly-nonlinear and weak-scatterer approaches. As nonlinear computational models, three ships are considered: original KVLCC2 hull, 'Ax-bow' and 'Leadge-bow' hulls. Two of the three models are modified hull forms of original KVLCC2 hull, aiming the reduction of added resistance. The nonlinear computational results are compared with linear results, and the improvement of computational result is discussed. As experimental approach, a series of towing-tank experiment for ship motions and added resistance on the three models (original KVLCC2 hull, 'Ax-bow' and 'Leadge-bow') are carried out. For the original KVLCC2 hull, uncertainty analysis in the measurement of vertical motion response and added resistance is performed in three waves conditions: ${\lambda}/L=0.5$, 1.1, 2.0. From the experimental results, the effects of hull form on added resistance are discussed.

• Journal of Ocean Engineering and Technology
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• v.25 no.4
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• pp.18-22
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• 2011

The Ranking source panel method was used to predict the flow phenomenon of a ship with a goose-neck type bulbous bow penetrating the free surface. The non-linearity of the free surface boundary condition was fully satisfied using an iterative calculation method, and the raised panel method was adopted to obtain a more stable solution at each iteration step. The panel cutting method was applied to generate a hull calculation grid at each iteration step, including the first step. At that time, the nose of the goose-neck type bulbous bow was divided by the free surface and the free surface panel was modified at each iteration step using the variable free surface panel method. Numerical calculations were performed to investigate the validity and efficiency of the applied numerical algorithm using the 3600 TEU container carrier. The computed wave resistance coefficients were compared with the experimentally achieved residual resistance coefficients.

• International Journal of Aeronautical and Space Sciences
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• v.15 no.1
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• pp.54-62
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• 2014

The Air and Space Interoperability Council (ASIC) has adopted the European Defence Agency (EDA) process for inter-regulatory military airworthiness authority recognition. However, there are gaps in the application of this process to nations outside of the European Union. This paper proposes a model that can effectively map diverse technical airworthiness regulatory frameworks. This model, referred to as the Product-Behaviour-Process (PBP) Bow-Tie model, provides the systematic structure needed to represent and compare regulatory frameworks. The PBP Bow-Tie model identifies key points of difference that need to be addressed, during inter-agency recognition between the two regulatory authorities. With the intention to adopt global use of the EDA process, the proposed PBP Bow-Tie model can be used as a basis for the successful recognition of regulatory frameworks outside of the European Union. Iris plots produced from the implementation of this model are presented, and proposed as a suitable means of illustrating the outcome of an assessment, and of supporting the comparisons of results. A comparative analysis of the Australian Defence Force and New Zealand Defence Force airworthiness regulatory frameworks is used as a case study. The case study clearly illustrates the effectiveness of the model in discerning regulatory framework differences; moreover, it has offered an opportunity to explore the limitations of the Iris plot.

• Journal of the Society of Naval Architects of Korea
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• v.54 no.1
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• pp.34-42
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• 2017

In rough seas, green water shipped on board may impose quite large impact loads on the structures on deck and sometimes result in structure damages. One of the essential tasks of the naval fluid engineers is to provide the design impact loads which are needed for proper design of the structure strength against the green water impacts. Computation of the design impact load due to green water needs first a process to find the sea condition and the ship cruising condition which cause maximum green water impacts on structures as well as other succeeding processes to compute ship motion responses, green water flows and impact loads. Also, as a bold and practical process, it is needed that the irregular real seas are to be substituted by design regular waves which are equivalent in view points of green water impacts. In this paper, the whole processes to compute the design green water loads acting on bow structure are set up creatively. And the green water design impact loads acting on the box-type structure of a high-speed ship's bow are computed and discussed.

• International Journal of Naval Architecture and Ocean Engineering
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• v.9 no.6
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• pp.641-654
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• 2017

The KVLCC2 and its modified hull form were investigated in regular head waves using Unsteady Reynolds Averaged Navier-Stokes (URANS) methods. The modified KVLCC2 (named KWP-bow KVLCC2) is designed for reducing wave reflection from the bow. Firstly, the original KVLCC2 is studied for verification of the present code and methodology and the computed time history of total resistance and 2DOF motions (heave and pitch) for the selected two wave length conditions are directly compared with the results obtained from KRISO towing tank experiment under the identical condition. The predicted added resistance, heave and pitch motion RAOs show relatively good agreement with the experimental results. Secondly, the comparison of performance in waves between KVLCC2 and KWP-bow KVLCC2 is carried out. We confirmed that newly designed hull form shows better performances in all the range of wave length conditions through both the computation and the experiment. The present URANS method can capture the difference of performance in waves of the two hull forms without any special treatment for short wave length conditions. It can be identified that KWP-bow KVLCC2 gives about 8% of energy saving in sea state 5 condition.

• The Journal of the Acoustical Society of Korea
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• v.35 no.1
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• pp.42-48
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• 2016

Since a variety of sound occur in same place and similar sound occurs in other places, the performance of acoustic scene classification is not guaranteed in case of insufficient training data. A Bag of Words (BOW) based histogram feature is foreseen as a method to overcome the problem. However, since the histogram features is made by using a feature distribution, the ordering of sequence of features is ignored. A temporal information such as periodicity and stationarity are also important for acoustic scene classification. In this paper, temporal features about a periodicity and a stationarity are extracted by using a recurrent quantification analysis. In the experiment, performance of the proposed method is shown better than other baseline methods.