• The Journal of Asian Finance, Economics and Business
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• v.9 no.4
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• pp.315-324
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• 2022

The goal of this study is to understand better the relationship between hospital bed occupancy rate and cost rigidity as a proxy for the degree of hospital bed congestion, as well as the relationship between the risk of changes in hospital bed occupancy rate and congestion cost, targeting public hospitals. As public hospitals for analysis, we selected hospital projects from the Public Enterprises Survey Reports published by the Department of Public Enterprises, Ministry of Finance, and obtained unbalanced panel data consisting of 1,505 hospitals and 15 years, totaling 12,595 hospitals and years. The analysis revealed that the risk of changes in the bed occupancy rate increases the degree of cost rigidity and leads to a decrease in the variable cost ratio; furthermore, an increase in the bed occupancy rate decreases the degree of cost rigidity and leads to an increase in the variable cost ratio. These findings suggest that although public hospitals are taking managerial actions to avoid congestion costs, congestion costs resulting from higher bed occupancy rates have not been eliminated. The regression analysis results show that even if congestion costs arise as the occupancy rate increases, they are covered by the increase in revenue associated with the increase in the occupancy rate.

• International Journal of Computer Science & Network Security
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• v.24 no.2
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• pp.178-188
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• 2024

In the near future, it is expected that there will be billions of connected devices using fifth generation (5G) network services. The recently available base stations (BSs) need to mitigate their loads without changing and at the least monetary cost. The available spectrum resources are limited and need to be exploited in an efficient way to meet the ever-increasing demand for services. Device to Device communication (D2D) technology will likely help satisfy the rapidly increasing capacity and also effectively offload traffic from the BS by distributing the transmission between D2D users from one side and the cellular users and the BS from the other side. In this paper, we propose to apply D2D overlay communication with cognitive radio capability in 5G networks to exploit unused spectrum resources taking into account the dynamic spectrum access. The performance metrics; throughput and delay are formulated and analyzed for CSMA-based medium access control (MAC) protocol that utilizes a common control channel for device users to negotiate the data channel and address the contention between those users. Device users can exploit the cognitive radio to access the data channels concurrently in the common interference area. Estimating the achievable throughput and delay in D2D communication in 5G networks is not exploited in previous studies using cognitive radio with CSMA-based MAC protocol to address the contention. From performance analysis, applying cognitive radio capability in D2D communication and allocating a common control channel for device users effectively improve the total aggregated network throughput by more than 60% compared to the individual D2D throughput without adding harmful interference to cellular network users. This approach can also reduce the delay.

• Journal of Korean Society of Rural Planning
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• v.13 no.1 s.34
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• pp.85-95
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• 2007

Hot springs development will be more activated with the five-day work week system than before. Nevertheless, investment and development achievement of hot springs has not resulted in a successful performance to foster townships, and this calls upon locals to build a guideline to develop hot springs. This study intends to analyze laws on hot springs, which influence mostly on the hot spring development, to gather up the information on the present state of the development, and to suggest considerations for further development plans. Features of the hot spring development are as follows: One is that metropolitan cities will discover hot spring resources more than small cities. Therefore the development will be twofold : one for resort tour and the other for one-day rest and recreation. In addition, Korean laws on hot springs are more site development-oriented to support tourism and recreation than to protect environment and discover unused resources. This makes hot spring development easier and efficient being supported by hot spring law, law on territory development and use, and tourism promotion law. On the other side, planned landscape trimming can be uniformized and unharmonized in terms of local identity and environment-friendliness. This is why careful considerations such as goods and bads of the local resources, local history and culture are needed in hot spring development. A long-term development project should include remodeling based on local identity and development trends. The third point indicates that Korean hot springs development has recorded relatively low performance due to difficult private capital attraction, and a high fence on land purchase and development approval. It is essential to release restrictions on the hot spring development-especially on those whose development performance has not been successful so that best practice can be supported by the government in remodeling and marketing. New plans on hot spring development should be also examined based on developer's capacity and local authorities' volition on the plan. Last point shows that most hot springs development plans have been designed only based on territory utilizing plan and facilities arrangement, not considering much on fund-raising, operational plan or feasibility analysis. Therefore the tourism promotion law should reinforce guidelines on tourist site approval system by supplementing criteria. At the same time, an education on tourism development planning is necessary to deepen developers' understanding, since most developers are experts more on city development, landscape architecture, designing, constructing and engineering than tourism development.

• Tunnel and Underground Space
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• v.31 no.6
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• pp.534-548
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• 2021

In this paper, the feasibility of generating solar power near an abandoned quarry is examined with the objectives of resolving the essential problems that quarries encounter, such as rockfalls and space usage issues. On an abandoned quarry site in Sadang, Seoul, Republic of Korea, two different PV installation methods were analyzed. The first is attaching PV directly on the quarry slope. Since there are no corresponding safety standards and precedents for installing solar panels directly on slopes, the power generation potential was calculated by using topographic data and reasonable assumptions. The surface area of cut slope section was extracted from the Digital Elevation Model(DEM) via ArcGIS and Python programming to calculate the tilt and power capacity of installable panels. The other approach is installing PV as a rockfall barrier, and the power generation potential was analyzed with the assumption that the panel is installed in the direction of facing solar irradiation. For the derivation of power generation, the renewable energy generation analysis program SAM(System Advisor Model) was used for both methods. According to the result, quarries that have terminated resource extraction and remain devastated have the potential to be transformed into renewable energy generation sites.

• Membrane Journal
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• v.32 no.5
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• pp.283-291
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• 2022

Hydrogen energy has received much attention as a solution to the supply of renewable energy and to respond to climate change. Hydrogen is the most suitable candidate of storing unused electric power in a large-capacity long cycle. Among the technologies for producing hydrogen, water electrolysis is known as an eco-friendly hydrogen production technology that produces hydrogen without carbon dioxide generation by water splitting reaction. Membranes in water electrolysis system physically separate the anode and the cathode, but also prevent mixing of generated hydrogen and oxygen gases and facilitate ion transfer to complete circuit. In particular, the key to next-generation anion exchange membrane that can compensate for the shortcomings of conventional water electrolysis technologies is to develop high performance anion exchange membrane. Many studies are conducted to have high ion conductivity and excellent durability in an alkaline environment simultaneously, and various materials are being searched. In this review, we will discuss the research trends and points to move forward by looking at the research on anion exchange membranes based on commercial polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS) block copolymers.