• Journal of Environmental Policy
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• v.9 no.2
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• pp.41-55
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• 2010

This paper analyzes optimal watershed management focusing on reservoir-level sediment removal techniques. Although dams and reservoirs provide several benefits, sedimentation may reduce their storage capacity. As of today, the Aswan High Dam (AHD) in Egypt faces approximately 76% reduced life of the reservoir. Since the AHD is the major fresh water source in Egypt, sustainable use of this resource is extremely important. A model is developed to simultaneously determine optimal sediment removal strategies for upstream soil conservation efforts and reservoir-level sediment control. Two sediment removal techniques are considered: mechanical dredging and hydro-suction sediment removal system (HSRS). Moreover, different levels of upstream soil conservation efforts have introduced to control soil erosion, which is a major contributor of reservoir storage capacity reduction. We compare a baseline case, which implies no management alternative, to non-cooperative and social planners' solution. Our empirical results indicate that the socially optimal sediment removal technique is a mechanical dredging with unconstrained amount with providing a sustainable life of the reservoir. From the empirical results, we find that social welfare can be as high as $151.01 billion, and is sensitive to interest rates and agricultural soil loss.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.42 no.4
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• pp.25-32
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• 2010

The beeswax-treated volumes of the Annals of Joseon Dynasty, designated as a UNESCO's Memories of the World, have been more seriously damaged than the untreated ones. As a continuous effort to develop the optimal conservation techniques for the damaged beeswax-treated volumes of the Annals, this study examines the effectiveness of wet cleaning on the conservation of the beeswax-treated paper. To do this, wet cleaning is performed on the duplicated beeswax-treated paper and the Hanji that are aged at $105^{\circ}C$ for 30 days using distilled water of $24^{\circ}C$ and $50^{\circ}C$. As results, it is observed that pH of the both the beeswax-treated paper and the Hanji increase, indicating the removal of the acid of the aged paper samples through wet cleaning. After the wet cleaning, however, the physical properties and viscosity of the Hanji decrease, while those of the beeswax-treated paper increase. It is also found that wet cleaning contributes to enhancement of most optical properties of the Hanji, but not for those of the beeswax-treated paper except for the $b^*$ value. Analyses of UV absorbance of cleaning water demonstrate that both the beeswax-treated paper and the Hanji have typical spectra of chromophore compounds of cellulose.

• Journal of Communications and Networks
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• v.18 no.4
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• pp.567-579
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• 2016

Several energy saving techniques in cellular wireless networks such as active base station (BS) selection, transmit power budget adaptation and user association have been studied independently or only part of these aspects have been considered together in literature. In this paper, we jointly tackle these three problems and propose an integrated framework, called dynamic cell reconfiguration (DCR). It manages three techniques operating on different time scales for ultimate energy conservation while guaranteeing the quality of service (QoS) level of users. Extensive simulations under various configurations, including the real dataset of BS topology and utilization, demonstrate that the proposed DCR can achieve the performance close to an optimal exhaustive search. Compared to the conventional static scheme where all BSs are always turned on with their maximum transmit powers, DCR can significantly reduce energy consumption, e.g., more than 30% and 50% savings in uniform and non-uniform traffic distribution, respectively.

• Korean Journal of Heritage: History & Science
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• v.55 no.1
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• pp.51-61
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• 2022

Earthenware horn cups with horse head decorations were excavated from Tomb No. 7 of Bokcheon-dong, Dongraegu, Busan Metropolitan City. Made of earth in the shape of a horn, these cups are considered to have been used to drink alcohol or beverage. Large numbers of earthenware horn cups of various shapes were excavated from tombs located in the old territories of Silla and Gaya. A pair of earthenware horn cups were excavated from Tomb No. 7, and the two cups are almost identical in overall shapes and manufacturing techniques despite different sizes. Conservation treatment was carried out for the bigger one of the two horn cups this time. There are two cracks toward the horse head decorations around the mouth with missing parts observed. The chest of the horse touches the ground with one side decorating the horse head and the other side facing the conical mouth of the horn cup. It is in the U shape, striking a balance based on two legs attached behind. The surface of the horn cup was made with a potter's wheel, and the connection to the horse head has traces of cutting and trimming. The horse head is expressed realistically with its features including the ears, eyes, nose, and mouth well apprehended and its color is grey This study intended to investigate manufacturing techniques of the artifact by examining its internal structure through the condition survey in a non-destructive way. CT imaging was used to figure out its manufacturing techniques and to diagnose its condition, and accordingly the scientific conservation treatment was conducted to stabilize the artifact. The precise diagnosis on conservation condition found that there are two chips in the spout with their cracks extended. One of the chips is connected with separation added to the crack. The material which has been used for connection in the past was collected for the infrared spectroscopic analysis, which was identified to be nitrocellulose resin for the connection. Therefore, this conservation treatment focused on removing the old material and preventing the spread of cracks. Before conservation treatment, the condition survey and scientific examination for the artifact were carried out to secure data about the earthenware horn cup with horse head decorations(Treasure). Based on them, effective plans for its conservation treatment was sought for and then existing adhesive was safely removed, and restoration material was selected to take into account its reversibility. In addition, the conservation treatment according to optimal methodologies was conducted through the consultation meeting with experts.

• Journal of Conservation Science
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• v.38 no.3
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• pp.201-216
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• 2022

Materials and techniques used for two portraits (Jo-nyeon Lee and S ung-in Lee) of the Lee family from Seongju enshrined in Seongsan temple were scientifically analyzed, and based on the data, an optimal replica restoration method was designed. According to the expression technique investigation, both portraits were expressed mainly in line drawing, but there were differences in shoes, pupils, the color expression of flesh, overpainting, and traces of reinforcement. Pigment analysis revealed that a mixture of cinnabar and minium, organic pigment, azurite, malachite, lead white, and yellow pigment were used in common. In the case of Sung-in Lee's portrait, seokganju and atacamite were also used. In addition, comparison with the contemporaneous portraits of gentry showed that the portrait style at the time was found in the two portraits, but the singularity was modified differently there. Based on the scientific analysis, it was decided to replicate the old color restoration for Jo-nyeon Lee's portrait while for Sung-in Lee's portrait, it was decided to replicate the phenomenon. Detailed coloring techniques were presented by supplementing the expression techniques that are difficult to confirm visually using scientific data. In addition, by measuring the chromaticity of representative positions in the portrait for each color and presenting the color reference value calculated as the average value, the current color of the artifact can be replicated and restored based on the objective data as much as possible.

• Journal of Wetlands Research
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• v.25 no.4
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• pp.257-266
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• 2023

Amphibian populations are declining globally, pushing many species to the brink of extinction. To promote biodiversity and sustainable management, countries are actively researching amphibian reproductive ecology. Sperm cryopreservation is a crucial assisted reproductive technology that aids in preserving the genetic diversity of amphibians. However, because amphibian sperm cells are sensitive to osmotic stress, the optimal cryopreservation method therefore differs from species to species. This literature review offers an overview of the significance of developing cryopreservation techniques for amphibian conservation and highlights the need to create optimal cryopreservation methods and the introduction of long-term monitoring (e.g., fertilization success and offspring reproduction) to advance cryopreservation technology development. This review can be used as basic research data for amphibian conservation methods.

• Journal of Conservation Science
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• v.35 no.3
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• pp.237-244
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• 2019

In this study, we applied terahertz imaging technology to three Korean modern oil paintings ('Boy,' 'Girl,' and 'Hyehwadong Landscape'); investigated the types of inner layer information in the pictures that can be extracted with terahertz imaging technology; and analyzed the conditions for extracting them. The biggest problem in the terahertz imaging analysis we encountered was the image distortion caused by the change of the distance between the target surface and the terahertz detector, depending on the surface curvature of the target paintings. We then developed a 'working distance maintaining device' to solve this problem. As a result, the terahertz imaging technique was used to identify the base material characteristics and any patterns of damage inside, and presented the optimal conditions for identifying each characteristic. In addition, it was useful to employ the terahertz frequency-division image to check the characteristics of the background materials. To confirm coloring techniques such as brush strokes, it is effective to compare the maximum reflection peak image with the cross-section image; and to detect damage information inside the paintings that cannot be observed on the surface, to compare the cross-section image with the frequency-division image. On the other hand, according to the terahertz imaging analysis of the oil paintings, the internal structural damage marks of 'Boy' and 'Girl' were confirmed, and the artist's painting style was confirmed in 'Hyehwadong Landscape.' The above results are expected to be useful for the analysis and diagnosis of Korean modern oil paintings for their preservation.

• The Transactions of the Korean Institute of Power Electronics
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• v.12 no.6
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• pp.433-440
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• 2007

Recently, the reduction of standby power consumption is significantly issued in electronic and electrical industry for the conservation of environment. In the case of a switched mode power supply (SMPS), it is demanded high efficiency at extremely low output power conditions by consumers. However, it is very different from high efficiency techniques at full load conditions. In addition, many SMPSs are designed as a multi-output circuit for various loads because of cost down. This circuit is difficult to implement both high efficiency and good cross regulation performance, simultaneously. In this paper, secondary side post regulator (SSPR), current mode control method, and power sequence control technique are proposed to reduce standby power consumption and to improve cross regulation performance of the multi-output SMPSs which consist of single or multiple converter. The proposed methods are analyzed by their operational principles and optimal designs verified by experimental results with 110[W] and 270[W] SMPSs.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.5
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• pp.418-428
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• 2007

In the calculation of wave propagation by Boussinesq equation model, it is very common to experience numerical noises generated from nonlinear interaction and breaking wave occurrence, and the numerical solution is rapidly diverged unless the noises are properly controlled. A comparative study was here undertaken for the characteristics of three different lowpass filters (FFT filter, Gaussian filter and Shapiro filter) which are all designed to be applied to the interim results of numerical calculation. The numerical results obtained with application of respective filter techniques were compared with the results of an existing hydraulic experiment for the aspects of noise suppression, conservation of main signal and altering time. The results show that the Shapiro filter can be best applied with optimal choices of its element number, pass number and filtering tune interval. The combination of the number of filter element off, pass number of 50 or less, and application interval of 100 to 200 time steps generally showed good performance in both accuracy and efficiency of the numerical calculation.

• Proceedings of the Korean Society of Grassland Science Conference
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• 2002.09b
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• pp.103-127
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• 2002

The main problem of the forage-based livestock farming in Germany at the moment is the high yielding cow requiring high energy concentration in feed which can be obtained lot easier with corn and grain than with grass. Therefore milk production tends out of the grassland region and into the forage crop region. Nutrient surplus due to concentrates in milk production in future probably will be limited by the government. The problem can only be solved by using best swards and optimal silage techniques as well as optimisation of manure utilization. Most important steps of sustainable forage production are care of grassland as well as regular resowing, especially of silage meadows. About 40% of Hessian grassland is managed in agri-environmental problems to keep it in use and to protect the natural resources. Selective measures are realized, to solve special problmes of nature and landscape conservation.