• Steel and Composite Structures
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• v.50 no.4
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• pp.419-428
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• 2024

Prefabricated partially-encased composite (PEC) structural component is widely used in construction industry due to its superior structural performance and easy assembly characteristic. However, the solid web in traditional PEC components tends to split concrete into two halves, thus potentially reduces structural integrity and requires double concrete pouring. To overcome the above disadvantages, a new PEC beam with open-web π-shaped steel is proposed in this paper. Four open-web PEC beams with varying sectional height, flange thickness and web void rate were constructed and tested under flexural loads. During experimental tests, all beams exhibited typical flexural failure modes with strong moment capacities and excellent ductility. Owing to the unique construction form of web opening, steel-concrete bonding properties were enhanced and very small relative steel-concrete slips were observed. Experimental results also showed that the flexural capacity of such PEC beams increased with the increase of the sectional height and flange thickness, while was not affected by the web void rate. At last, a flexural capacity formula of the open-web PEC beam was proposed based on the whole section plastic rule. The formula results agreed well with experimental results.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.213-216
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• 2015

Despite the significant increase of Korean contractors in the international construction market, many SMCCs (Small & Medium Construction Companies) have suffered in the global financial crisis, and some of them have been kicked out of the international market after experiencing huge losses on projects. SMCCs face obstacles in the international market, such as an insufficient ability to gather information and inappropriate management of associated risks, which lead to difficulties in establishing effective business strategies. In other words, making immature decisions without an effective business strategy may cause not only the failure of one project but also the bankruptcy of the SMCC. To overcome this, the research presented herein aims to propose a decision support system for SMCCs, which would screen projects and make a go/no-go decision at the early stages of international projects. The proposed system comprises a double axis: (1) a profit prediction model, which evaluates 10 project properties using an objective methodology based on a historical project performance database and roughly suggests expected profit rate, and (2) a feasibility assessment model, which evaluates 17 project environment factors in a subjective and quantitative methodology based on experience and supervision. Finally, a web-based system is established to enhance the practical usability, which is expected to be a good reference for inexperienced SMCCs to make proper decisions and establish effective business strategies.

• Journal of Technology Innovation
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• v.26 no.3
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• pp.37-68
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• 2018

Since the 20th century, automobiles, which are the most common means of transportation, have been evolving as the use of electronic control devices and automotive semiconductors increases dramatically. Automotive semiconductors are a key component in automotive electronic control devices and are used to provide stability, efficiency of fuel use, and stability of operation to consumers. For example, automotive semiconductors include engines control, technologies for managing electric motors, transmission control units, hybrid vehicle control, start/stop systems, electronic motor control, automotive radar and LIDAR, smart head lamps, head-up displays, lane keeping systems. As such, semiconductors are being applied to almost all electronic control devices that make up an automobile, and they are creating more effects than simply combining mechanical devices. Since automotive semiconductors have a high data rate basically, a microprocessor unit is being used instead of a micro control unit. For example, semiconductors based on ARM processors are being used in telematics, audio/video multi-medias and navigation. Automotive semiconductors require characteristics such as high reliability, durability and long-term supply, considering the period of use of the automobile for more than 10 years. The reliability of automotive semiconductors is directly linked to the safety of automobiles. The semiconductor industry uses JEDEC and AEC standards to evaluate the reliability of automotive semiconductors. In addition, the life expectancy of the product is estimated at the early stage of development and at the early stage of mass production by using the reliability test method and results that are presented as standard in the automobile industry. However, there are limitations in predicting the failure rate caused by various parameters such as customer's various conditions of use and usage time. To overcome these limitations, much research has been done in academia and industry. Among them, researches using data mining techniques have been carried out in many semiconductor fields, but application and research on automotive semiconductors have not yet been studied. In this regard, this study investigates the relationship between data generated during semiconductor assembly and package test process by using data mining technique, and uses data mining technique suitable for predicting potential failure rate using customer bad data.

• Clinical and Experimental Reproductive Medicine
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• v.20 no.2
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• pp.117-123
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• 1993

The condition of the endometrium is an important factor which may influence the success or failure in IVF-ET. This study was undertaken for evaluation of the value of endometrial growth as an early predictor for the success of IVF. Ultrasonographic endometrial measurement were performed in 43 IVF cycles that conceived, 101 cycles that did not with an IVF-ET There was no significant difference in the endometrial thickness and the serum concentration of estradiol in the pregnant versus nonpregnant group(10.4 vs. 9.9 mm: 2348 vs. 2017 pg/ml no hCG administration day). No correlation was found between the ultrasound image and serum estradiol levels around the time of hCG administration(r=0.54, p=0.13 no Day 2; r=0.45, p=0.14 no Day 1). The duration of gonadotropin treatment, number of follicles, number of oocytes retrieved, and fertilization rate were not statistically different in the two groups, however, there was a significant difference in the number of embryos in the pregnant versus nonpregnant group)p< 0.05). A higher pregnancy rate and ongoing pregnancy rate occured with an endometrial thickness over 11 mm compared with below 7mm(p< 0.05, p< 0.005). however, no significant differences were noted in the implantation rate and abortion rate among the groups that classified according to their endmetrial thickness. The endometrial growth(${\Delta}$) from hCG administration day(DO) to D6 was greater in the women who achieved pregnancy than in the nonpregnant group(p< 0.01). There were no significant differences in serum estradiol levels, implantation rate, pregnancy rate, and abortion rate among the groups that classified according to the pattern of echogenesity of endometrium, however, significantly higher ongoing pregnancy rate was noted in group A, B compared with group C.(p< 0.0001, p< 0.001) These results suggest that there were no ultrasonographically detectable differences in the patterns of endometrial growth and development around the time of hCG administration in patients who conceive versus those that do not in IVF-ET.

• Journal of Power Electronics
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• v.18 no.5
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• pp.1608-1617
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• 2018

The rapid and correct isolation of faulty submodules (SMs) is of great importance for improving the reliability of modular multilevel converters (MMCs). Therefore, a fast diagnosis method containing fault detection and fault location determination was presented in this paper. An improved incremental predictive model of arm current was proposed to detect failures, and the multi-step prediction method was used to eliminate the negative impact of disturbances. Moreover, a control method was proposed to strengthen the fault characteristics to rapidly locate faulty arms and faulty SMs by detecting the variation rate of the SM capacitor voltage. The proposed method can rapidly and easily locate faulty SMs under different load conditions without the need for additional sensors. The experimental results have validated the effectiveness of the proposed method by using a single-phase MMC with four SMs per arm.

• The Journal of Korea Robotics Society
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• v.15 no.4
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• pp.398-403
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• 2020

Robot's throwing control is difficult to accurately calculate because of air resistance and rotational inertia, etc. This complexity can be solved by using machine learning. Reinforcement learning using reward function puts limit on adapting to new environment for robots. Therefore, this paper applied deep reinforcement learning using neural network without reward function. Throwing is evaluated as a success or failure. AI network learns by taking the target position and control policy as input and yielding the evaluation as output. Then, the task is carried out by predicting the success probability according to the target location and control policy and searching the policy with the highest probability. Repeating this task can result in performance improvements as data accumulates. And this model can even predict tasks that were not previously attempted which means it is an universally applicable learning model for any new environment. According to the data results from 520 experiments, this learning model guarantees 75% success rate.

• Advances in pediatric surgery
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• v.3 no.2
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• pp.126-132
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• 1997

Reduction of intussusception using air or oxygen has wide acceptance as an alternative to conventional hydrostatic reduction. This study was undertaken to evaluate the results and complications of air pressure enema in 948 pediatric intussusception. One hundred and twenty nine cases were operated on at the Department of Surgery, Masan Samsung Hospital from 1985 to 1996 because of air reduction failure. The success rate was 86.4 %. Twenty-one patients(2.2 %) showed perforation during air reduction. Risk prone factors of perforation were; age less than 3 months(42.9 % vs 11.1 %), duration of symptoms greater than 48 hours (66.7 % vs 33.3 %), and presence of pathologic leading point(28.6 % vs 3.7 %). Vomitting and spontaneous rectal bleeding revealed higher prediction to the complication. In nineteen cases, bowel infarction, coagulated necrosis and hemorrhage suggested that the cause of perforation was due to the preexisting strangulation. In conclusion, when doing an air pressure enema reduction, care must be taken if the patient is of a young age or the symptoms are of long duration.

• Tunnel and Underground Space
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• v.8 no.2
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• pp.130-138
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• 1998

Comprehensive monitoring system for the safe and economical excavation of underground opening has been established by employing the 3 independent models each of which can i) predict the ultimate convergence, ii) assess the in-situ stresses and the elastic modulus of excavating rock, iii) calculate the time-dependent opening behavior with respect to the face advance rate and support pressure at the equilibrium state. Accuracy of each model has been verified through illustrative examples. The step-by-step procedures of comprehensive monitoring system for analyzing the rock behavior and the optimum support installation has been explained. The capability and applicability of this system to the practical excavation also has been discussed.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.77-81
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• 2005

본 논문은 열차제어시스템의 고장률을 정량적으로 예측하고 입증하기 위한 방안을 제시한다. 고장률의 정량적 예측은 시스템 개발단계에서 하부시스템별 고장발생확률을 예측하여 목표 고장률과 비교하고, 고장률이 높은 하부시스템의 설계를 보완하기 위함이다. 시제품이 완성된 후에는 예측된 고장률의 입증을 위해 시운전을 통한 고장데이터를 분석하거나 신뢰성시험을 통해 고장률의 예측치를 입증한다. 본 논문에서 제시하는 열차제어시스템 고장률예측과 입증은 철도신호시스템 신뢰성, 가용성, 유지보수성, 안전성관련 규격인 IEC62278의 시스템 수명주기별 신뢰성활동을 근거로 하며, 전자부품으로 구성된 시스템고장률예측은 미국방부 전자부품 고장률예측 지침인 MIL-HDBK-217을 기준으로 사용하였다.

• International Journal of Ocean System Engineering
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• v.1 no.1
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• pp.37-45
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• 2011

The nonlinear free-surface motions interacting with a floating body were investigated using the Moving Particle Semi-implicit (MPS) method proposed by Koshizuka and Oka [6] for incompressible flow. In the numerical method, more realistic Lagrangian moving particles were used for solving the flow field instead of the Eulerian approach with a grid system. Therefore, the convection terms and time derivatives in the Navier-Stokes equation can be calculated more directly, without any numerical diffusion, instabilities, or topological failure. The MPS method was applied to a numerical simulation of predicting the efficiency of floating-type breakwater interacting with waves.