• Journal of The Korean Society of Agricultural Engineers
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• v.51 no.4
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• pp.49-55
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• 2009

This paper is to induce design floods through L-moment with 3 and 4 parameter Kappa distributions including test of independence by Wald-Wolfowitz, homogeneity by Mann-Whitney and outlier by Grubbs-Beck on annual maximum flood flows at 9 water level gaging stations in Han, Nakdong and Geum Rivers of South Korea. After analyzing appropriateness of the data of annual maximum flood flows by Kolmogorov-Smirnov test, 3 and 4 Kappa distributions were applied and the appropriateness was judged. The parameters of 3 and 4 Kappa distributions were estimated by L-moment method and the design floods by water level gaging station was calculated. Through the comparative analysis using the relative root mean square errors (RRMSE) and relative absolute errors (RAE) calculated by 3 and 4 parameter Kappa distributions with 4 plotting position formulas, the result showed that the design floods by 4 parameter Kappa distribution with Weibull and Cunnane plotting position formulas are closer to the observed data than those obtained by 3 parameter Kappa distribution with 4 plotting position formulas and 4 parameter Kappa distribution with Hazen and Gringorten plotting position formulas.

• The KSFM Journal of Fluid Machinery
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• v.13 no.3
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• pp.24-29
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• 2010

Axial fans for an air-conditioning unit are designed to equip the system with an expected flow-rate and low noise level by applying the blade design method of multi-sectioning and local camber generation. In this study, the distributions of chord length, stagger angle, and camber angle are globally and locally determined for the given specific speed, which is considered to be relatively high. The mock-up fans are observed to satisfy the aerodynamic performance and the noise level for the system simultaneously and discussed in terms of local flow patterns related to the emitted noise.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05a
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• pp.484-490
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• 1996

The Pressurizer Level Control System (PLCS) logic for YGN 5&6 was developed to incorporate the design changes on the Chemical and Volume Control System (CVCS). The YGN 5&6 CVCS uses the centrifugal charging pumps and letdown orifices replacing the positive displacement pumps and letdown control valves in the YGN 3&4 and UCN 3&4. The purpose of this study is to develop new PLCS as well as validate newly developed control logic and its implementation method in the simulation computer code. The analysis results show that the new PLCS has adequate ability to control the pressurizer level in response to the design bases events, and the simulation computer code is useful for YGN 5&6 NSSS design code.

• Geomechanics and Engineering
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• v.32 no.4
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• pp.387-396
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• 2023

Ground subsidence, which is a current concern that affects piled raft foundations, has occurred at a high rate in Ho Chi Minh City, Viet Nam, due primarily to groundwater pumping for water supply. In this study, the groundwater level (GWL) change affect on a piled raft foundation was investigated based on the three-dimensional finite element method (3D-FEM) using the PLAXIS 3D software. The GWL change due to global groundwater pumping and dewatering were simulated in PLAXIS 3D based on the GWL reduction and consolidation. Settlement and the pile axial force of the piled raft foundation in Ho Chi Minh subsoil were investigated based on the actual design and the proposed optimal case. The actual design used the piled foundation concept, while the optimal case applied a pile spacing of 6D using a piled raft concept to reduce the number of piles, with little increased settlement. The results indicated that the settlement increased with the GWL reduction, caused by groundwater pumping and dewatering. The subsidence started to affect the piled raft foundation 2.5 years after construction for the actual design and after 3.4 years for the optimal case due to global groundwater pumping. The pile's axial force, which was affected by negative skin friction, increased during that time.

• Structural Engineering and Mechanics
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• v.50 no.3
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• pp.305-322
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• 2014

Reliability-based design limit states and associated partial load factors provide a consistent level of design safety across bridge types and members. However, limit states in the current AASHTO LRFD have not been developed explicitly for the situation encountered by integral abutment bridges (IABs) that have unique boundary conditions and loads with inherent uncertainties. Therefore, new reliability-based limit states for IABs considering the variability of the abutment support conditions and thermal loading must be developed to achieve IAB designs that achieve the same safety level as other bridge designs. Prestressed concrete girder bridges are considered in this study and are subjected to concrete time-dependent effects (creep and shrinkage), backfill pressure, temperature fluctuation and temperature gradient. Based on the previously established database for bridge loads and resistances, reliability analyses are performed. The IAB limit states proposed herein are intended to supplement current AASHTO LRFD limit states as specified in AASHTO LRFD Table 3.4.1-1.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.972-975
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• 2004

In order to reduce the noise of BLDC motor, a systematic optimization procedure for rotor structure is presented. The noise index is defined as the sum of volume velocity of FE-model that are calculated at the dominant frequencies during dehydration process, which is based on the principle of radiation simple volume source. Then, the five design variables are selected to represent the shape and layout or rotor structure. This discrete design optimization problem for minimizing the noise index is solved by 3-level orthogonal array based effect analysis. Finally, the response surface method (RSM) combined optimization approach is employed for more refining the approximate optimum.

• Therapeutic Science for Rehabilitation
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• v.10 no.4
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• pp.39-52
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• 2021

Objective : This study aimed to identify the characteristics and analyze the quality of studies on memory improvement using a single-subject research design. Methods : Six studies were selected through the Research Information Sharing Service (RISS), Korean Studies Information Service System (KISS), and National Digital Science Library (NDSL). Keywords were memory training, stroke, early dementia, mild cognitive impairment, and single-subject research design. The characteristics and quality levels were analyzed between January 2011 and October 2020. Results : Regarding the quality level, the middle level (7-10 points) was 66.7% of the four articles, and the high level (11-14 points) was 33.3% of the two articles. Reversal designs were used in all studies. Independent variables were errorless learning, smartphone application, cognitive training system (CoTras), spaced retrieval training (SRT) with errorless learning, spaced retrieval training, and iPad applications. The dependent variables included memory, attention, electroencephalogram, instrumental activities of daily living, depression etc., which increased after the intervention. The total session, study period, and intervention time were varied. Conclusion : In single-subject research design related to memory training, occupational therapy intervention was confirmed as an effective method for improving memory and attention. The quality level of single-subject research design was moderate or higher, and high-quality level of studies should be conducted by additional design to increase the validity in the future.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.11
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• pp.745-750
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• 2010

Since the implementation of the LMO Law in Korea, the importance of the design qualification of BSL3 lab. is emphasizing. In this study, multizone simulation for three kind of biohazard scenarios using CONTAM is performed for design qualification of BSL3 lab. Also, in the case of unexpected spread of contaminants such as Influenza A virus(H1N1) in BL3 zone, the design qualification is carried out for diffusion and decontamination of contaminants according to differential pressure of BSL3 anteroom and door area of BSL3 lab. Also, in this study, appropriateness of laboratory room differential pressure and air flow rate to maintain pressure difference between laboratory rooms, and energy consumption due to air change rate variation according to door area in BL3 lab. Simulation results show that these approach methods are used as a tool for the design and verification of BL3 lab.

• Korean Journal of Computational Design and Engineering
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• v.16 no.3
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• pp.236-245
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• 2011

Many researchers have recently studied multi-level formulation strategies to solve the MDO problems and they basically distributed the coupling compatibilities across all disciplines, while single-level formulations concentrate all the controls at the system-level. In addition, approximation techniques became remedies for computationally expensive analyses and simulations. This paper studies comparisons of the MDO methods with respect to computing performance considering both conventional sequential and modem distributed/parallel processing environments. The comparisons show Individual Disciplinary Feasible (IDF) formulation is the most efficient for sequential processing and IDF with approximation (IDFa) is the most efficient for parallel processing. Results incorporating to popular design examples show this finding. The author suggests design engineers should firstly choose IDF formulation to solve MDO problems because of its simplicity of implementation and not-bad performance. A single drawback of IDF is requiring more memory for local design variables and coupling variables. Adding cheap memories can save engineers valuable time and effort for complicated multi-level formulations and let them free out of no solution headache of Multi-Disciplinary Analysis (MDA) of the Multi-Disciplinary Feasible (MDF) formulation.

• Korean Journal of Computational Design and Engineering
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• v.21 no.1
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• pp.78-89
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• 2016

When a plant owner requests plant 3D CAD models in the format that a shipbuilding company does not use, the shipyard manually re-models plant 3D CAD models according to the owner's requirement. Therefore, it is important to develop a technology to compare the re-modeled plant 3D CAD models with original ones and to quantitatively evaluate similarity between two models. In the previous study, we developed a graphic user interface (GUI)-based comparison system where a user evaluates similarity between original and re-modeled plant 3D CAD models for piping design at the level of unit. However, an offshore plant consists of thousands of units and thus a system which compares several plant 3D CAD models at unit-level without human intervention is necessary. For this, we developed a new batch model comparison system which automatically evaluates similarity of several unit-level plant 3D CAD models using an extensible markup language (XML) file storing file location and name data about a set of plant 3D CAD models. This paper suggests system configuration of a batch-mode-based comparison system and discusses its core functions. For the verification of the developed system, comparison experiments for offshore plant 3D piping CAD models using the system were performed. From the experiments, we confirmed that similarities for several plant 3D CAD models at unit-level were evaluated without human intervention.