• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.4
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• pp.157-164
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• 2023

This paper suggests O(n²) polynomial time heuristic algorithm for corporate tax structure optimization problem that has been classified as NP-complete problem. The proposed algorithm constructs tax tree levels that the target holding company is located at root node of Level 1, and the tax code categories(T_e) 1,4,3,2 are located in each level 2,3,4,5 sequentially. To find the maximum tax-relief path from source(S) to target(T), firstly we connect the minimum witholding tax rate _minr_w(u, v) arc of node u point of view for transfer the profit from u to v node. As a result we construct the spanning tree from all of the source nodes to a target node, and find the initial feasible solution. Nextly, we find the alternate path with minimum foreign tax rate _minr_fi(u, v) of v point of view. Finally we choose the minimum tax-relief path from of this two paths. The proposed heuristic algorithm performs better optimal results than linear programming and Tabu search method that is a kind of metaheuristic method.

• Journal of the Korean Geotechnical Society
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• v.22 no.11
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• pp.89-99
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• 2006

The PCRW (Precast Concrete Retaining Wall) has many advantages compared with cast in place concrete retaining wall : shorter construction period, excellency of quality and minimum interference with the adjacent structure and traffics. However, shallow foundation type of PCRW, which has comparatively better ground condition, has some disadvantages such as difficulty in transportation and higher cost due to the size of PCRW being expanded by resisting only with self-weight if there is no other supplementary reinforcement. The presented study, in order to complement such disadvantages of PCRW, have applied the micropile method. The micropile method has advantages like low-cost and high-efficiency and does not require huge space, because it can be executed with small size equipment. However, the mechanical behavior characteristics of the PCRW reinforced by micropile, which is installed to improve the reinforcement effect, is not yet clearly identified and there is no suggested standard as to the length, diameter, install angle and install position of micropiles. Hence, this method is yet being designed depend on engineer's experience. In this study, various laboratory model tests as to sliding and overturning were performed in order to identify and present the optimum type of reinforcement and reinforcement effect of the PCRW reinforced by micropiles. In addition, it also executed numerical analysis for the purpose of verifying the optimum type of reinforcement for micropiles based on the results of laboratory model tests. The optimum reinforcement type of micropiles was estimated by model test and numerical analysis. The length of micropiles is 0.4 times wall height and the diameter is 0.04 times wall length.

• Journal of the Korean Geotechnical Society
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• v.22 no.6
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• pp.15-26
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• 2006

Although numerous investigations have been performed over the years to predict the behavior and bearing capacity of piles, the mechanisms are not yet entirely understood. The prediction of bearing capacity is a difficult task, because large numbers of factors affect the capacity and also have complex relationship one another. Therefore, it is extremely difficult to search the essential factors among many factors, which are related with ground condition, pile type, driving condition and others, and then appropriately consider complicated relationship among the searched factors. The present paper describes the application of Artificial Neural Network (ANN) in predicting the capacity including its components at the tip and along the shaft from dynamic load test of the driven piles. Firstly, the effect of each factor on the value of bearing capacity is investigated on the basis of sensitivity analysis using ANN modeling. Secondly, the authors use the design methodology composed of ANN and genetic algorithm (GA) to find optimal neural network model to predict the bearing capacity. The authors allow this methodology to find the appropriate combination of input parameters, the number of hidden units and the transfer structure among the input, the hidden and the out layers. The results of this study indicate that the neural network model serves as a reliable and simple predictive tool for the bearing capacity of driven piles.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.29 no.1
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• pp.1-7
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• 2023

Chlorine dioxide (ClO₂) is widely used for post-harvest sterilization treatment. However, there are limitations in the retail application of ClO₂ due to difficulties in handling, expensive facilities, and safety concerns. Therefore, it is necessary to develop a ClO₂ technology that can be easily applied and continuously released for a long period. In this study, a series of ClO₂ self-releasing sachets were developed. First, poly(ether-block-amide) (PEBAX) and polyethylene-glycol (PEG) composite films containing different ratios of citric acid (CA) were prepared using the solution casting method. The as-prepared PEBAX/PEG-CA composite films were evaluated using FT-IR, DSC, and TGA to confirm chemical structure and thermal properties. Subsequently, PEBAX/PEG-CA composite films were designed in the form of a sachet and NaClO₂ powder was transferred into the sachet to achieve a ClO₂ self-releasing system. The ClO₂-releasing behavior of the sachet was investigated by measuring the release amount of the gas using UV-vis. The release amount of ClO₂ increased with increasing CA contents owing to the existence of higher protons (trigger) in the polymer matrix. Further, ClO₂ gas was released for a longer time. Therefore, the as-prepared smart sachet can be tuned according to applications and packaging sizes to serve an optimal sterilization effect.

• Composites Research
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• v.36 no.3
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• pp.211-216
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• 2023

When designing ships and aircraft structures, it is important to design them to satisfy weight reduction and strength. Currently, studies related to topology optimization using 3D printed composite materials are being actively conducted to satisfy the weight reduction and strength of the structure. In this study, structural analysis was performed to analyze the applicability of 3D printed composite materials to the flight control surface, one of the parts of an aircraft or unmanned aerial vehicle. The optimal topology shape of the flight control surface for the bending load was analyzed by considering three types (hexagonal, rectangular, triangular) of the topology shape of the flight control surface. In addition, the bending strength of the flight control surface was analyzed when four types of reinforcing materials (carbon fiber, glass fiber, high-strength high-temperature glass fiber, and kevlar) of the 3D printed composite material were applied. As a result of comparing the three-point bending test results with the finite element method results, it was confirmed that the flight control surface with hexagonal topology shape made of carbon fiber and Kevlar had excellent performance. And it is judged that the 3D printed composite can be sufficiently applied to the flight control surface.

• Analytical Science and Technology
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• v.21 no.1
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• pp.58-63
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• 2008

Nano-sized ZnO crystals were successfully incorporated using ion exchange method in TMA-A zeolite synthesized by the hydrothermal method. The optimal composition for the synthesis of TMA-A zeolite was resulted in a solution of $Al(i-pro)_3$ : 2.2 TEOS : 2.4 TMAOH : 0.3 NaOH : 200 $H_2O$. 0.3 g of TMA-A zeolite and 5 mol of $ZnCl_2$ solution were employed for the preparation of ZnO incorporated TMA-A zeolite. The crystallization process of ZnO incorporated TMA-A zeolite was analyzed by X-ray diffraction (XRD). The incorporated nano-sized ZnO crystals and the crystallinity of TMA-A zeolite were evaluated by transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). The size of the incorporated nano-sized ZnO crystals was 3~5 nm, while the TMA-A zeolite was 60~100 nm. The bonding structure and absorption of the ZnO incorporated TMA-A zeolite were compared with the ZnO and TMA-A zeolite by the FT-IR analysis. Subsequentlly, the ZnO incorporated TMA-A zeolite showed the photoluminescent characteristics on the wavelengths of 330~260 nm and 260~230 nm by measurement of UV spectrophotometer.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.3D
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• pp.295-302
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• 2010

Since the late 1990s, the BOT mode in China has been extensively used in the water sector in order to attract private investment, improve technical and operational efficiency, and expand the coverage of water services. The BOT mode has been hailed as this provides a win-win structure between the government and private players through formalized procedures and an optimal risk allocation. However, recent market analyses show that some foreign investors are reluctant to participate in the market or even retreat due to uncertainties and risks in the market. This study aims to explore various risks in the Chinese water BOT market based on the thorough literature review, fieldwork, and the case studies on the two wholly foreign-owned BOT water projects: the Chengdu No. 6 and the Shanghai Dachang Water Supply BOT projects. The research results indicate that the Chinese BOT market embraces high risks in political, institutional and legal, and financial systems. The key to a successful takeoff of the BOT mode in the Chinese water market depends on the extent to which the government will be able to remove risky factors in political, institutional and legal, and financing systems. This research outcome will provide a useful reference to the Korean construction companies which consider expanding business to overseas water markets in the form of public private partnership.

• Journal of the Microelectronics and Packaging Society
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• v.30 no.3
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• pp.111-118
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• 2023

MXene, a two-dimensional transition metal carbide or nitride, has recently attracted much attention as a lightweight and flexible electromagnetic shielding material due to its high electrical conductivity, good mechanical strength and thermal stability. In particular, the Ti-based MXene, Ti₃C₂T_x and Ti₂CT_x are reported to have the best electrical conductivity and electromagnetic shielding properties in the vast MXene family. Therefore, in this study, Ti₃C₂T_x and Ti₂CT_x films were prepared by vacuum filtration using Ti₃C₂T_x and Ti₂CT_x dispersions synthesized by interlayer metal etching and centrifugation of Ti₃AlC₂ and Ti₂AlC. The electrical conductivity and electromagnetic shielding efficiency of the films were measured after heat treatment at high temperature. Then, X-ray diffraction and photoelectron spectroscopy were performed to analyze the structural changes of Ti₃C₂T_x and Ti₂CT_x films after heat treatment and their effects on electromagnetic shielding. Based on the results of this study, we propose an optimal structure for an ultra-thin, lightweight, and high performance MXene-based electromagnetic shielding film for future applications in small and wearable electronics.

• Industry Promotion Research
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• v.8 no.4
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• pp.267-276
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• 2023

Based on the tourism input-output data of five provinces and cities in China's Bohai Rim region from 2015~2021, this study analyzes the efficiency of regional tourism using DEA-BCC and DEA-Malmquist index, as well as its contribution to regional economic efficiency, and identifies factors influencing the comprehensive efficiency. The research results indicate that the comprehensive efficiency of the tourism industry in the China Bohai Sea region has reached an optimal level of 88.9%, but there is still room for improvement, with overall fluctuations. The overall productivity of the tourism industry exhibits a "U"-shaped fluctuating pattern, with growth mainly driven by technological advancements. Due to the impact of the COVID-19 pandemic, the region experienced a nearly 50% decrease in total factor productivity in 2019~2020. However, in 2021, with the implementation of various government stimulus policies, the tourism efficiency rapidly recovered to 80% of pre-pandemic levels. In terms of the impact of the tourism industry on the regional economy in the China Bohai Sea region, Hebei Province stands out as a significant contributor. Based on the aforementioned research findings, the following recommendations are proposed in three aspects: optimizing the supply structure, increasing innovation investment, and strengthening internal collaboration. These recommendations provide valuable insights for enhancing regional tourism efficiency and promoting regional synergy.

• Journal of the Korean Institute of Landscape Architecture
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• v.52 no.2
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• pp.96-109
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• 2024

The purpose of this study is to propose a method for evaluating the similarity of Show gardens using Deep Learning models, specifically VGG-16 and ResNet50. A model for judging the similarity of show gardens based on VGG-16 and ResNet50 models was developed, and was referred to as DRG (Deep Recognition of similarity in show Garden design). An algorithm utilizing GAP and Pearson correlation coefficient was employed to construct the model, and the accuracy of similarity was analyzed by comparing the total number of similar images derived at 1st (Top1), 3rd (Top3), and 5th (Top5) ranks with the original images. The image data used for the DRG model consisted of a total of 278 works from the Le Festival International des Jardins de Chaumont-sur-Loire, 27 works from the Seoul International Garden Show, and 17 works from the Korea Garden Show. Image analysis was conducted using the DRG model for both the same group and different groups, resulting in the establishment of guidelines for assessing show garden similarity. First, overall image similarity analysis was best suited for applying data augmentation techniques based on the ResNet50 model. Second, for image analysis focusing on internal structure and outer form, it was effective to apply a certain size filter (16cm × 16cm) to generate images emphasizing form and then compare similarity using the VGG-16 model. It was suggested that an image size of 448 × 448 pixels and the original image in full color are the optimal settings. Based on these research findings, a quantitative method for assessing show gardens is proposed and it is expected to contribute to the continuous development of garden culture through interdisciplinary research moving forward.