• Title/Summary/Keyword: Keio University

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Comparison of various k-ε models and DSM applied to flow around a high-rise building - report on AIJ cooperative project for CFD prediction of wind environment -

  • Mochida, A.;Tominaga, Y.;Murakami, S.;Yoshie, R.;Ishihara, T.;Ooka, R.
    • Wind and Structures
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    • v.5 no.2_3_4
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    • pp.227-244
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    • 2002
  • Recently, the prediction of wind environment around a building using Computational Fluid Dynamics (CFD) technique comes to be carried out at the practical design stage. However, there have been very few studies which examined the accuracy of CFD prediction of flow around a high-rise building including the velocity distribution at pedestrian level. The working group for CFD prediction of wind environment around building, which consists of researchers from several universities and private companies, was organized in the Architectural Institute of Japan (AIJ) considering such a background. At the first stage of the project, the working group planned to carry out the cross comparison of CFD results of flow around a high rise building by various numerical methods, in order to clarify the major factors which affect prediction accuracy. This paper presents the results of this comparison.

A Direct Utility Model with Dynamic Constraint

  • Kim, Byungyeon;Satomura, Takuya;Kim, Jaehwan
    • Asia Marketing Journal
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    • v.18 no.4
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    • pp.125-138
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    • 2017
  • The goal of the study is to understand how consumers' constraint as opposed to utility structure gives rise to final decision when consumers purchase more than one variant of product at a time, i.e., horizontal variety seeking or multiple-discreteness. Purchase and consumption decision not only produces utility but also involves some sort of cognitive pressure. Past consumption or last purchase is likely to be linked to this burden we face such as concern for obesity, risk of harm, and guilt for mischief. In this research, the existence and the role of dynamic constraint are investigated through a microeconomic utility model with multiple dynamic constraint. The model is applied to the salty snacks data collected from field study where burden for spiciness serves as a constraint. The results are compared to the conventional multiple discreteness choice models of static constraints, and policy implications on price discounts is explored. The major findings are that first, one would underestimate the level of consumer preference for product offerings when ignoring the carry-over of the concern from the past consumption, and second, the impact of price promotion on demand would be properly evaluated when the model allows for the role of constraint as both multiple and dynamic. The current study is different from the existing studies in two ways. First, it captures the effect of 'mental constraint' on demand in formal economic model. Second, unlike the state dependence well documented in the literature, the study proposes the notion of state dependence in different way, via constraint rather than utility.

A novel technique for large and ptotic breast reconstruction using a latissimus dorsi myocutaneous flap set at the posterior aspect, combined with a silicone implant, following tissue expander surgery

  • Ishii, Naohiro;Ando, Jiro;Shimizu, Yusuke;Kishi, Kazuo
    • Archives of Plastic Surgery
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    • v.45 no.5
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    • pp.484-489
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    • 2018
  • Large and ptotic breast reconstruction in patients who are not candidates for a transverse rectus abdominalis myocutaneous flap and revision surgery for the contralateral breast remains challenging. We developed a novel breast reconstruction technique using a latissimus dorsi myocutaneous (LD m-c) flap set at the posterior aspect of the reconstructed breast, combined with an anatomical silicone breast implant (SBI), following tissue expander surgery. We performed the proposed technique in four patients, in whom the weight of the resected tissue during mastectomy was >500 g and the depth of the inframammary fold (IMF) was >3 cm. After over-expansion of the lower portion of the skin envelope by a tissue expander, the LD m-c flap was transferred to cover the lower portion of the breast defect and to achieve a ptotic contour, with the skin paddle set at the posterior aspect of the reconstructed breast. An SBI was then placed in the rest of the breast defect after setting the LD m-c flap. No major complications were observed during the follow-up period. The proposed technique resulted in symmetrical and aesthetically satisfactory breasts with deep IMFs, which allowed proper fitting of the brassiere, following large and ptotic breast reconstruction.

The Anatomic Features and Role of Superficial Inferior Epigastric Vein in Abdominal Flap

  • Park, Seong Oh;Imanishi, Nobuaki;Chang, Hak
    • Archives of Plastic Surgery
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    • v.49 no.4
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    • pp.482-487
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    • 2022
  • In lower abdominal flap representing transverse rectus abdominis musculocutaneous (TRAM) flap or deep inferior epigastric perforator (DIEP) flap, superficial inferior epigastric vein (SIEV) exists as superficial and independent venous system from deep system. The superficial venous drainage is dominant despite a dominant deep arterial supply in anterior abdominal wall. As TRAM or DIEP flaps began to be widely used for breast reconstruction, venous congestion issue has been arisen. Many clinical series in regard to venous congestion despite patent microvascular anastomosis site were reported. Venous congestion could be divided in two conditions by the area of venous congestion and each condition is from different anatomical causes. First, if venous congestion was shown in whole flap, it is due to the connection between SIEV and vena comitantes of DIEP. Second, if venous congestion is limited in above midline (Hartrampf zone II), it is due to problem in venous midline crossover. In this article, the authors reviewed the role of SIEV in lower abdominal flap based on the various anatomic and clinical studies. The contents are mainly categorized into four main issues; basic anatomy of SIEV, the two cause of venous congestion, connection between SIEV and vena comitantes of DIEP, and midline crossover of SIEV.

Postbuckling strength of an axially compressed elastic circular cylinder with all symmetry broken

  • Fujii, Fumio;Noguchi, Hirohisa
    • Structural Engineering and Mechanics
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    • v.11 no.2
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    • pp.199-210
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    • 2001
  • Axially compressed circular cylinders repeat symmetry-breaking bifurcation in the postbuckling region. There exist stable equilibria with all symmetry broken in the buckled configuration, and the minimum postbuckling strength is attained at the deep bottom of closely spaced equilibrium branches. The load level corresponding to such postbuckling stable solutions is usually much lower than the initial buckling load and may serve as a strength limit in shell stability design. The primary concern in the present paper is to compute these possible postbuckling stable solutions at the deep bottom of the postbuckling region. Two computational approaches are used for this purpose. One is the application of individual procedures in computational bifurcation theory. Path-tracing, pinpointing bifurcation points and (local) branch-switching are all applied to follow carefully the postbuckling branches with the decreasing load in order to attain the target at the bottom of the postbuckling region. The buckled shell configuration loses its symmetry stepwise after each (local) branch-switching procedure. The other is to introduce the idea of path jumping (namely, generalized global branch-switching) with static imperfection. The static response of the cylinder under two-parameter loading is computed to enable a direct access to postbuckling equilibria from the prebuckling state. In the numerical example of an elastic perfect circular cylinder, stable postbuckling solutions are computed in these two approaches. It is demonstrated that a direct path jump from the undeformed state to postbuckling stable equilibria is possible for an appropriate choice of static perturbations.

A Study on the Architecture of Choryang Waekwan and Historical Landscape (초량왜관 건축과 역사적 경관 재현 연구)

  • Boo, Hak-Joo;Kim, Chung-Dong
    • Journal of architectural history
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    • v.15 no.3
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    • pp.81-98
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    • 2006
  • Choryang Waekwan was the biggest Japanese settlment to house the Japanese diplomatic mission and traders in Korea. Waekwan means Japanese Pavilion literally, but the reality of this Waekwan exceeded much the scale of single architecture. Since Choryang Waekwan was closed in the second half of the nineteenth century, the site of this settlement grew rapidly as the downtown of Busan, which was the first port open to foreign countries in modern Korea. The formation of modern port owes much to the presence of Japanese settlment in Lee Dynasty as long as Choryang was officially designated as the trading port toward Japan and vice versa. Busan is the nearest city to Japan, in fact. Within a day ships could reach Tsushima Island, the island region north of Fukuoka, which played an intermediary role between Seoul and Edo. No architectural remain could be seen on the actual site of Choryang Waekwan. The site has become one of the busiest centers in Busan with quantify of office buildings and shops. The former Busan City Hall was located in this area. The field survey of the site as well as the analysis of historical documents, which were newly found both in Korea and in Japan, enabled to reconstruct the architecture and cityscape of Waekwan by way of computer graphics.

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Detailed Finite Element Analysis of Full-scale Four-story Steel Frame Structure subjected to Consecutive Ground Motions

  • Tagawa, Hiroyuki;Miyamura, Tomoshi;Yamashita, Takuzo;Kohiyama, Masayuki;Ohsaki, Makoto
    • International Journal of High-Rise Buildings
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    • v.4 no.1
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    • pp.65-73
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    • 2015
  • Detailed finite element (FE) analyses of a full-scale four-story steel frame structure, subjected to consecutive 60% and 100% excitations from the JR Takatori records during the 1995 Hyogoken-Nanbu earthquake, are conducted using E-Simulator. The four-story frame was tested at the largest shake-table facility in the world, E-Defense, in 2007. E-Simulator is a parallel FE analysis software package developed to accurately simulate structural behavior up to collapse by using a fine mesh of solid elements. To reduce computational time in consecutive dynamic time history analyses, static analysis with gravity force is introduced to terminate the vibration of the structure during the analysis of 60% excitation. An overall sway mechanism when subjected to 60% excitation and a story mechanism resulting from local buckling of the first-story columns when subjected to 100% excitation are simulated by using E-Simulator. The story drift response to the consecutive 60% and 100% excitations is slightly smaller than that for the single 100% excitation.

Study on Standstill Conditions in Kaizen Activity: Through Case Studies of Two Companies in their Long-Term Efforts

  • Yamaguchi, Jun;Kono, Hirokazu
    • Industrial Engineering and Management Systems
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    • v.16 no.1
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    • pp.80-91
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    • 2017
  • Multiple prior studies stress that continued Kaizen activity is conducive to building and maintaining competitive advantages of manufacturing companies. Meanwhile, it remains unclear as to what kind of management factors may exert impact on sustainment of Kaizen activity. This paper discusses a study conducted on the cases of two manufacturing lines, where such activity has been continued for more than ten years. At first, it was discovered that study period was divided into different periods. It was also found out that 'standstill conditions' which prevent smooth progress of activity exist in many periods, and that such conditions are hard to avoid. The study went on to categorize progress of activity in each period into different patterns, including at which points standstill conditions occurred, thereby, circumstances of standstill conditions were made clear. This paper verified a detailed process of Kaizen activity development in each period and the relationship between that detailed process and points of occurrence of standstill conditions. Thought was also given to factors and actions for smooth development, and effects brought about by overcoming such challenges. Lastly, consideration was given to the future perspectives of the study for elucidating how better Kaizen activity may be managed for continuation.

Early warning of hazard for pipelines by acoustic recognition using principal component analysis and one-class support vector machines

  • Wan, Chunfeng;Mita, Akira
    • Smart Structures and Systems
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    • v.6 no.4
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    • pp.405-421
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    • 2010
  • This paper proposes a method for early warning of hazard for pipelines. Many pipelines transport dangerous contents so that any damage incurred might lead to catastrophic consequences. However, most of these damages are usually a result of surrounding third-party activities, mainly the constructions. In order to prevent accidents and disasters, detection of potential hazards from third-party activities is indispensable. This paper focuses on recognizing the running of construction machines because they indicate the activity of the constructions. Acoustic information is applied for the recognition and a novel pipeline monitoring approach is proposed. Principal Component Analysis (PCA) is applied. The obtained Eigenvalues are regarded as the special signature and thus used for building feature vectors. One-class Support Vector Machine (SVM) is used for the classifier. The denoising ability of PCA can make it robust to noise interference, while the powerful classifying ability of SVM can provide good recognition results. Some related issues such as standardization are also studied and discussed. On-site experiments are conducted and results prove the effectiveness of the proposed early warning method. Thus the possible hazards can be prevented and the integrity of pipelines can be ensured.

Rigidity Evaluation under Uncertainties for Multiple Investment Alternatives over Multiple Periods

  • Kono, Hirokazu;Mizumachi, Tadahiro
    • Industrial Engineering and Management Systems
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    • v.9 no.2
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    • pp.107-120
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    • 2010
  • In today's uncertain economic environment, the evaluation of safety for investment alternatives is of practical importance in manufacturing companies. This paper examines a method of quantitatively evaluating profitability and risk for multiple alternatives using the total-cost unit-cost domain. The paper assumes such factors as unit sales price, sales and production volume, unit variable cost, fixed cost, and yield for each alternative. The paper incorporates the relationship between production capacity and demand, distinguishing between cases of production capacity surplus and shortage for each year over the entire planning horizon. The paper investigates the case in which the values of each factor independently move in the direction of decreasing profit each year, and clarifies the procedure of comparing safety among multiple investment alternatives on a single consolidated total-cost unit-cost domain. The difficulty of the problem lies in the method of consolidating multiple total-cost unit-cost domains into a single domain since the combination of years of capacity surplus and shortage depends upon the change values in each factor under consideration. A systematic method of evaluating profitability as well as risk is presented, and the validity of the proposed method is verified using a numerical example.