• Title/Summary/Keyword: Full scale model test

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Experimental investigation of dynamic trim control devices in fast speed vessel (고속선의 트림제어 장치가 항주 자세 및 저항 성능에 미치는 영향)

  • Seo, Kwang-Cheol;Gopakumar, Nithin;Atlar, Mehmet
    • Journal of Navigation and Port Research
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    • v.37 no.2
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    • pp.137-142
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    • 2013
  • The displacement Deep-V catamaran concept was developed in Newcastle University(UNEW) through development of the systematic Deep-V catamaran series. One of the most important Deep-V catamaran launched to date is Newcastle University's own multi-purpose research vessel, The Princess Royal. The vessel was launched in 2011 and enhanced the Deep-V catamaran concept further with the successful adoption of a novel anti-slamming bulbous bow and tunnel stern for improved efficiency. It was however identified that the vessel has substantial amount of dynamic trim that limited the visibility of the captain. The dynamic trim also increased the wave-making resistance thereby preventing the vessel from attaining its maximum speed in certain sea states. This paper therefore presents the application of devices such as Trim Tabs, Interceptors, Transom Wedges and Integrated Transom Wedges-Tabs to control the dynamic trim and improvement of fuel efficiency of the vessel. All of these energy saving devices were fitted into a model for tests in Newcastle University's Towing Tank. Model test verification confirmed that the optimum appendage was the interceptors, they produced a 5% power saving and 1.2 degree trim reduction at 15 knots, and investigations of full scale trials will be scheduled with and without application of device to compare the improvement of performance.

A Study on Calculation of Local Ice Pressures for ARAON Based on Data Measured at Arctic Sea (북극해 계측자료에 기초한 아라온호의 국부 빙압력 계산 연구)

  • Lee, Tak-Kee;Kim, Tae-Wook;Rim, Chae Whan;Kim, Sungchan
    • Journal of Ocean Engineering and Technology
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    • v.27 no.5
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    • pp.88-92
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    • 2013
  • The icebreaking research vessel (IBRV) ARAON had her second ice trial in the Arctic Ocean in the summer season of 2010. During the voyage, the local ice loads acting on the bow of the port side were measured using 14 strain gauges. These measurements were carried out in three icebreaking performance tests. To convert the measured strains into the local ice pressures, a finite element model of the instrumented area was developed. The influence coefficient method (ICM), which uses the influence coefficient from the finite element model, and the direct method, which uses the measured strain, were selected as the conversion methods. As a result, the maximum measured pressure was 1.236MPa, and the average difference between ICM and the direct method was about 5% for an area of $0.2m^2$. The pressure-area relationship of the measurement falls below the range of the existing pressure-area curve, which is due to the low ice strength of melted ice in the summer.

A Study on the Hull Form Design and Ice Resistance & Propulsion Performance of a Platform Support Vessel (PSV) Operated in the Arctic Ocean (극지해역 운용 해양작업지원선(PSV)의 선형설계와 빙 저항추진 성능 연구)

  • Yum, Jong-Gil;Kang, Kuk-Jin;Jang, Jin-ho;Jeong, Seong-Yeob
    • Journal of the Society of Naval Architects of Korea
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    • v.55 no.6
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    • pp.497-504
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    • 2018
  • Platform Support Vessels operated in the Arctic Ocean support diverse operations of offshore plant in the sea, and the PSV is also needed to support works to exploit the oil and gas in the Arctic Ocean. Both of the ice breaking and the open sea performance have been considered together to secure the enhanced operational performance at the harsh environment in the Arctic Ocean and the open sea as well. In this study, One of the design requirements of a PSV is to guarantee continuous icebreaking performance with 3 knots at 1 m thickness of level ice, where the design draft is 7.5m and the engine power is 13 MW. Three hull forms were designed, and the ice resistance based on empirical formulas was estimated to select the initial hull form having an outstanding performance. The full scale performance of the designed hull forms was predicted by the ice model test conducted in the ice model basin of Korea Research Institute of Ships & Ocean Engineering(KRISO). The analysed results show that the selected hull form satisfies the above design requirement.

Prediction Model for Specific Cutting Energy of Pick Cutters Based on Gene Expression Programming and Particle Swarm Optimization (유전자 프로그래밍과 개체군집최적화를 이용한 픽 커터의 절삭비에너지 예측모델)

  • Hojjati, Shahabedin;Jeong, Hoyoung;Jeon, Seokwon
    • Tunnel and Underground Space
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    • v.28 no.6
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    • pp.651-669
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    • 2018
  • This study suggests the prediction model to estimate the specific energy of a pick cutter using a gene expression programming (GEP) and particle swarm optimization (PSO). Estimating the performance of mechanical excavators is of crucial importance in early design stage of tunnelling projects, and the specific energy (SE) based approach serves as a standard performance prediction procedure that is applicable to all excavation machines. The purpose of this research, is to investigate the relationship between UCS and BTS, penetration depth, cut spacing, and SE. A total of 46 full-scale linear cutting test results using pick cutters and different values of depth of cut and cut spacing on various rock types was collected from the previous study for the analysis. The Mean Squared Error (MSE) associated with the conventional Multiple Linear Regression (MLR) method is more than two times larger than the MSE generated by GEP-PSO algorithm. The $R^2$ value associated with the GEP-PSO algorithm, is about 0.13 higher than the $R^2$ associated with MLR.

A Study on the Precedents Changing Related to International Jurisdiction in Electronic Commerce-Focused on U.S. Cases- (전자상거래의 국제재판관할 관련 판례변화에 관한 연구)

  • Woo, Kwang-Myung
    • International Commerce and Information Review
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    • v.13 no.3
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    • pp.3-29
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    • 2011
  • The Internet has become a medium through which people engage in increasingly sophisticated transactions. Businesses and consumers now use the Internet to communicate and engage in commercial transactions creating a virtual worldwide marketplace. They fear that the determination of Internet jurisdiction could be uncertain because electronic commerce is not executed in one particular place. Until now, there are no specific rules in the model laws and conventions dealing with international jurisdiction in electronic commerce. Due to the fact that U.S. companies are at the forefront of Internet technology, litigation regarding electronic commerce in the U.S. is more advanced than anywhere else in the world This paper analysis the basic framework for personal jurisdiction and approach for determining international jurisdiction in electronic commerce cases and explain the differences of several approaches involving interactions over the Internet. According to jurisdiction approach test, the U.S. employs sliding scale, effects and targeting test in electronic commerce. In recent many research views the targeting test as a global standard for determining international electronic commerce jurisdiction. However, there is still no clear indication of conclusive test of jurisdiction determination for electronic commerce. Therefore, it is a changing and process of jurisdiction test in the U.S. cases. In Korea, there is jurisdiction related clause in Private International Law, but it may be asked whether applicable in electronic commerce. Accordingly, analysis of the precedents changing related to electronic commerce jurisdiction of U.s. is full of suggestions in Korean companies, consumers and helps an enactment of code of civil procedure that containing many group's demands.

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A Study on the Behaviour of Fish Schools in the Process of Catch of the Purse Seine Fishing Method (선망어법의 어획과정에 있어서 어군행동에 관한 연구)

  • Park, Jeong-Sik;Kim, Seok-Jong;Kim, Sam-Gon
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.33 no.3
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    • pp.173-182
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    • 1997
  • This study is a basic research in purse seine fishery : on the behaviour of fish schools of tilapia Tilapia mossambica in the process of catch of the purse seine fishing method. The experiment was carried out for the mackerel purse seine which using of power block by fishing fleet system in the near sea of Cheju Island and as a forecast in the near future on the purse seine fishing, using of triplex net winch by one boat system in the near sea of Norway. These model purse seines were made of the scale of 1/180 of its full scale. The model purse seine test on the escaping behaviour of fish school by gap, area reducing of gap and tension of purse line was carried out in the stagnant water of experimental water tank. Designing and testing for the model purse seines were based on the Tauti's law. The results obtained were as follows : 1. When the time for the completing of pursing was 20 minutes, average swimming speed of fish school through a gap was 9.71cm/sec for powerblock seine and 9.97cm/sec for triplex seine. 2. In the case of pursing time in actual value was 20minutes, at 50 percent of the pursing, swimming behaviour of fish school in purse seine was 10% to I section, 80% to II section, 10% to III sectional direction for powerblock seine and a similar tendency for triplex seine. 3. In the case of pursing time in actual value was 20 minutes, at the time of 10 minutes have proceeded since then, area reducing rate of gap of the seine in projected front view was 63.5% for powerblock seine and 67.5% for triplex seine. 4. In the case of pursing time in actual value was 20 minutes, escaping rate of fish school by gap in projected front view was 70% for powerblock seine and 30% for triplex seine. Maximum tension of purse line was about 8.1 tons for powerblock seine and about 8.3 tons for triplex seine.

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Validity and Reliability Evaluation of Pregnancy Related Stress Scale (임부 스트레스 측정도구의 신뢰도 및 타당도 평가)

  • Lee, Hyejung;Seo, Minjeong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.6
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    • pp.503-512
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    • 2017
  • The perceived stress of pregnant women is a potential contributor to adverse birth outcomes. Although the importance of the psychosocial well-being of pregnant women has been emphasized, there are fewreliable and valid instruments to measure the stress level of pregnant women in Korea. This study evaluated the psychometric properties of Ahn's pregnancy related stress scale (PSS) that was originally developed in 1984. Two hundred pregnant women completed the survey questionnaire, which was comprised of the PSS, depression scale, and demographic information. Principal component analysis and confirmatory factor analysis was used to test the construct validity. The concurrent validity was evaluated using the correlation with depression scores. Based on exploratory factor analysis and a consideration of conceptual meaning, a five-factor structure was extracted, explaining 57.25% of the variance: physical discomfort, fetus, parenting, spouse relationship, and housework. The goodness-of-fit indices showed an acceptable fit overall with the full model and acceptable internal consistency (Cronbach's alpha =.89). The concurrent validity was confirmed by a comparing with the depression score (r=.48, p <.001). The shortened PSS, as a valid and reliable scale, is recommended to be used to assess pregnancy-related stress and to develop stress managing interventions for pregnant women in clinical settings.

Context Prediction Using Right and Wrong Patterns to Improve Sequential Matching Performance for More Accurate Dynamic Context-Aware Recommendation (보다 정확한 동적 상황인식 추천을 위해 정확 및 오류 패턴을 활용하여 순차적 매칭 성능이 개선된 상황 예측 방법)

  • Kwon, Oh-Byung
    • Asia pacific journal of information systems
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    • v.19 no.3
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    • pp.51-67
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    • 2009
  • Developing an agile recommender system for nomadic users has been regarded as a promising application in mobile and ubiquitous settings. To increase the quality of personalized recommendation in terms of accuracy and elapsed time, estimating future context of the user in a correct way is highly crucial. Traditionally, time series analysis and Makovian process have been adopted for such forecasting. However, these methods are not adequate in predicting context data, only because most of context data are represented as nominal scale. To resolve these limitations, the alignment-prediction algorithm has been suggested for context prediction, especially for future context from the low-level context. Recently, an ontological approach has been proposed for guided context prediction without context history. However, due to variety of context information, acquiring sufficient context prediction knowledge a priori is not easy in most of service domains. Hence, the purpose of this paper is to propose a novel context prediction methodology, which does not require a priori knowledge, and to increase accuracy and decrease elapsed time for service response. To do so, we have newly developed pattern-based context prediction approach. First of ail, a set of individual rules is derived from each context attribute using context history. Then a pattern consisted of results from reasoning individual rules, is developed for pattern learning. If at least one context property matches, say R, then regard the pattern as right. If the pattern is new, add right pattern, set the value of mismatched properties = 0, freq = 1 and w(R, 1). Otherwise, increase the frequency of the matched right pattern by 1 and then set w(R,freq). After finishing training, if the frequency is greater than a threshold value, then save the right pattern in knowledge base. On the other hand, if at least one context property matches, say W, then regard the pattern as wrong. If the pattern is new, modify the result into wrong answer, add right pattern, and set frequency to 1 and w(W, 1). Or, increase the matched wrong pattern's frequency by 1 and then set w(W, freq). After finishing training, if the frequency value is greater than a threshold level, then save the wrong pattern on the knowledge basis. Then, context prediction is performed with combinatorial rules as follows: first, identify current context. Second, find matched patterns from right patterns. If there is no pattern matched, then find a matching pattern from wrong patterns. If a matching pattern is not found, then choose one context property whose predictability is higher than that of any other properties. To show the feasibility of the methodology proposed in this paper, we collected actual context history from the travelers who had visited the largest amusement park in Korea. As a result, 400 context records were collected in 2009. Then we randomly selected 70% of the records as training data. The rest were selected as testing data. To examine the performance of the methodology, prediction accuracy and elapsed time were chosen as measures. We compared the performance with case-based reasoning and voting methods. Through a simulation test, we conclude that our methodology is clearly better than CBR and voting methods in terms of accuracy and elapsed time. This shows that the methodology is relatively valid and scalable. As a second round of the experiment, we compared a full model to a partial model. A full model indicates that right and wrong patterns are used for reasoning the future context. On the other hand, a partial model means that the reasoning is performed only with right patterns, which is generally adopted in the legacy alignment-prediction method. It turned out that a full model is better than a partial model in terms of the accuracy while partial model is better when considering elapsed time. As a last experiment, we took into our consideration potential privacy problems that might arise among the users. To mediate such concern, we excluded such context properties as date of tour and user profiles such as gender and age. The outcome shows that preserving privacy is endurable. Contributions of this paper are as follows: First, academically, we have improved sequential matching methods to predict accuracy and service time by considering individual rules of each context property and learning from wrong patterns. Second, the proposed method is found to be quite effective for privacy preserving applications, which are frequently required by B2C context-aware services; the privacy preserving system applying the proposed method successfully can also decrease elapsed time. Hence, the method is very practical in establishing privacy preserving context-aware services. Our future research issues taking into account some limitations in this paper can be summarized as follows. First, user acceptance or usability will be tested with actual users in order to prove the value of the prototype system. Second, we will apply the proposed method to more general application domains as this paper focused on tourism in amusement park.

Experimental Evaluation of the Punching Shear Strength with Lightweight Aggregate Concrete Slabs (경량골재 콘크리트 바닥판의 펀칭전단강도의 실험적 평가)

  • Kim, Jung-Joong;Moon, Ji-Ho;Youm, Kwang-Soo
    • Journal of the Korea Concrete Institute
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    • v.26 no.3
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    • pp.361-367
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    • 2014
  • This paper investigates the punching shear strength of lightweight aggregate concrete (LWAC) slabs through a series of experimental study. Five full scale slabs were constructed using normal concrete and four different types of LWAC. Each lightweight aggregate (LWA) used in this study had different sources (clay, shale, or slate) and shapes (crushed or spherical shape). Based on the test results, the effect of the lightweight aggregates (LWA) on the punching shear behavior was investigated. From the test results, it was found that the punching shear failure surface of LWAC slab with spherical shape coarse aggregate was less inclined than that with crushed shape coarse aggregate, which resulted in an increase of the area of the shear failure surface. As a result, it leads to the increased punching shear strength of the slab. On the other hand, the failure surfaces of LWAC slab with crushed shape coarse aggregate and normal coarse aggregate were inclined similarly. Finally, the test results of this study were compared with the punching shear strength obtained from current design models, such as ACI and CEB-FIP, to examine the validation of current design model to predict the punching shear strength of the LWAC slab.

The Effects of Fear of Failure Factors Affecting Entrepreneurial Intentions of Startup Business Candidate (예비창업자의 실패에 대한 두려움이 창업의도에 미치는 영향)

  • Kim, Soojin;Han, Jungwha;Lee, Sangmyung
    • Asia-Pacific Journal of Business Venturing and Entrepreneurship
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    • v.11 no.3
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    • pp.49-61
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    • 2016
  • This study investigates the relationship between fear of failure of potential entrepreneur's psychological characteristics and entrepreneurial intentions using the mediation variables of planned behavior model. There are many existing prior research related to the entrepreneurial intentions, but they were mostly focused only entrepreneurial success factors. So in this study we focused on fear of failure of potential entrepreneur. To know the influence of the fear of failure related to entrepreneurial intention, we using the scale of PFAI (Performances Failure Appraisal Inventory). The purpose of this study is to examine an impact of fear of failure on entrepreneurial intention and add to mediating factors - attitude toward the acts, subjective norm, perceived behavior control - on the relationship between fear of failure and entrepreneurial intention. Also we examined entrepreneurial education as moderating effect in order to offset the fear of failure. In order to test research model, we collected data from 321 undergraduate students. To test the research questions and hypotheses, we employed SPSS 21.0 anf AMOS 18.0 for validity, reliability, confirmatory factor analysis, and structural model analysis. The results were as follows. First, the fear of failure negatively related to attitude toward the behavior and subjective norm. Second, attitude toward the behavior and subjective norm positively related to entrepreneurial intention in consistent with previous studies. Third, attitude toward the acts and subjective norm in TPB variables have full-mediation effects between fear of failure and intrepreneurial intention. Fourth, The moderating effects of entrepreneurial effect was not significant. The negative relationship between fear of failure and attitude toward the acts and subjective norm was even slightly stronger who have taken the entrepreneurial class group. We discuss the theoretical and managerial implications, and provide suggestions for future research.

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