• Korean Journal of Ichthyology
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• v.34 no.2
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• pp.86-95
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• 2022

Egg development and morphological change of larvae and juvenile of the Roughscale sole, Clidoderma asperrimum, were investigated in the present study. Adult fishes were collected on the East Sea, Korea, from 2017 to 2018 and reared in a circular water tank (Ø 6×1 m) at water temperature of 12.8±1.9℃. Fertilized eggs ranged from 1.42 to 1.59 mm (mean 1.51±0.04 mm, n=50) in diameter. The eggs were spherical in shape, transparent, floating and colorless. The egg yolk was separated from the egg membrane 60 mins post-fertilization (PF), and an embryo was formed in 62 hrs PF. More than 50% of the eggs hatched within 144 hrs PF in the range of 10.2~11℃(mean 10.8℃). The size of the newly hatched larvae were 4.22~4.64 mm (mean 4.53±0.16 mm) in total length (TL), their mouth and anus were not open yet. At 10 days after hatching, the preflexion larvae reached 5.88~6.62 mm (mean 6.31±0.33 mm) in TL, and the yolk absorption was completed and the mouth began to open. At 55 days after hatching the larvae reached to flexion larvae stage and they were 10.4~13.3 mm (mean 12.7±1.3 mm) in TL, and the tip of notochord was bent upward. At 120 days after hatching the larvae reached to juvenile stage and they were 35.3~40.5 mm (mean 39.5±2.4 mm) in TL. Their all fins had completed set of the fin-rays (D. 79~94: A. 63~75) and the juveniles adopted a benthic life.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.6
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• pp.371-384
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• 2021

Underground space, especially very-deep tunnel development in urban area, is a good alternative to solve the problem of insufficient ground space, and the need for underground space development is steadily increasing. However, due to the complex and time-consuming nature of design and construction, public conflicts related to the deep tunnel project are getting aggravating and more complex. In addition, since the public budget is mainly invested, when civil complaints arise, they often respond passively, resulting in amplification of conflicts or prolonging the deadlock in many cases. In this study, by analyzing the progress of major conflicts related to the construction of very-deep tunnels in urban area, the causes of conflicts, factors prolonging conflicts, and solutions are reviewed. Through a survey targeting ordinary citizens and tunnel experts, thoughts about the deep tunnel construction and major conflict factors were analyzed, and suggestions for minimizing conflicts were presented. The results of this study can be used to prepare alternatives such as various public involvement measures and improvement of project procedures to form a civic consensus on the construction of very-deep tunnels, and to prepare measures to improve prejudice against very-deep tunnels.

• Resources Recycling
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• v.31 no.1
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• pp.37-45
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• 2022

The development of the electrical, electronic, and telecommunication industries has increased the share of electricity in total energy consumption. With the enforcement of the Act on the Promotion of the Development, Use, and Diffusion of New and Renewable Energy in 2021, the mandatory supply ratio of new and renewable energy is expected to expand, and the amount of waste cables generated in the stage of replacing and discarding cables used in the industry is also expected to increase. The purpose of this study was to quantify the environmental burden of waste cable recycling through the life cycle assessment (LCA) method. The results showed that the higher the amount of glue contained in the waste cable, the greater was the amount of fine dust and greenhouse gases generated. In addition, by assigning weights to 10 environmental burden items, it was confirmed that the marine aquatic eco-toxicity potential (MAETP) and human toxicity potential (HTP) had the greatest environmental burden. The main causes were identified as heptane and ethanol, which were the glue contained in the waste cable and the cleaning solutions used to remove them. Therefore, it is necessary to refrain from using glue in the cable production process and reduce the environmental burden by reducing the use of waste cable cleaning solutions used in the recycling process or using alternative materials.

• Resources Recycling
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• v.31 no.1
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• pp.56-64
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• 2022

Construction waste is generated at a rate of approximately 221,102 tons/day in Korea. In particular, mixed construction waste generates approximately 24,582 tons/day. The other components were recycled by 98.9%. The amount of greenhouse gas emissions from the waste was 17.1 million tons of CO2 equaling 2.3% of the total greenhouse gas emissions. To reduce greenhouse gas emissions, reducing the environmental impact is becoming increasingly important. However, appropriate treatment must first be established, as mixed construction waste is also increasing. Thus, an effective plan is urgently needed because it is frequently segregated and sorted by the landfill and incinerated. In addition, there is an urgent need to prepare various effective recycling methods rather than a simple treatment. Therefore, this study analyzed the environmental impact of the treatment of mixed construction waste by calculating greenhouse gas emissions. As a result, the highest greenhouse gas generation occurred during the incineration stage. Moreover, the optimal method to reduce greenhouse gas emissions is recycling and energy recovery from waste. In addition, the amount of greenhouse gas generated during energy recovery from the waste stage was the second highest. However, greenhouse gas emissions can be reduced by using waste as energy to reduce fossil fuel consumption. In addition, for the transportation stage, the optimal reduction plan is to minimize the amount of greenhouse gas emissions by setting the optimal distance and applying biofuel and electric vehicle operations.

• Geophysics and Geophysical Exploration
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• v.25 no.1
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• pp.26-37
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• 2022

Recently, multiple methods using small aircraft for geophysical exploration have been suggested as a result of the development of information and communication technology. In this study, we introduce the hybrid unmanned aircraft electromagnetic system of the Korea Institute of Geosciences and Mineral resources, which is under development. Additionally, data processing and interpretation methods are suggested via the analysis of datasets obtained using the system under development to verify the system. Because the system uses a three-component receiver hanging from a drone, the effects of rotation on the obtained data are significant and were therefore corrected using a rotation matrix. During the survey, the heights of the source and the receiver and their offsets vary in real time and the measured data are contaminated with noise. The noise makes it difficult to interpret the data using the conventional method. Therefore, we developed a recurrent neural network (RNN) model to enable rapid predictions of the apparent resistivity using magnetic field data. Field data noise is included in the training datasets of the RNN model to improve its performance on noise-contaminated field data. Compared with the results of the electrical resistivity survey, the trained RNN model predicted similar apparent resistivities for the test field dataset.

• Journal of Internet Computing and Services
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• v.23 no.1
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• pp.31-38
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• 2022

An electrocardiogram(ECG) is a recoding of electrical signals of the heart's cyclic activity and an important body information for diagnosing myocardial rhythm. Large amount of information are generated continuously and a significant period of cumulative signal is required for the purpose of diagnosing a specific disease. Therefore, research on compression including clinically acceptable lossy technique has been developed to reduce the amount of information significantly. Recently, wearable smart heart monitoring devices that can transmit electrocardiogram(ECG) are being developed. The use of electrocardiogram, an important personal information for healthcare service, is rapidly increasing. However, devices generally have limited capability and power consumption for user convenience, and it is often difficult to apply the existing compression method directly. It is essential to develop techniques that can process and transmit a large volume of signals in limited resources. A method for compressing and transmitting the ECG signals efficiently by using the cumulative average (template) of the unit waveform is proposed in the paper. The ECG is coded lovelessly using template matching. It is analyzed that the proposed method is superior to the existing compression methods at high compression ratio, and its complexity is not relatively high. And it is also possible to apply compression methods to template matching values.

• Journal of Internet Computing and Services
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• v.23 no.1
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• pp.125-134
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• 2022

The development of information communication and artificial intelligence technology requires the intelligent command and control (C2) system for Korean military, and various studies are attempted to achieve it. In particular, as a volume ofinformation in the C2 workflow increases exponentially, this study pays attention to the collaborative filtering (CF) and recommendation systems (RS) that can provide the essential information for the users of the C2 system has been developed. The RS performing information filtering in the C2 system should provide an explanatory recommendation and consider the context of the tasks and users. In this paper, we propose a contextual pre-filtering CARS framework that recommends information in the C2 workflow. The proposed framework consists of four components: 1) contextual pre-filtering that filters data in advance based on the context and relationship of the users, 2) feature selection to overcome the data sparseness that is a weak point for the CF, 3) the proposed CF with the features distances between the users used to calculate user similarity, and 4) rule-based post filtering to reflect user preferences. In order to evaluate the superiority of this study, various distance methods of the existing CF method were compared to the proposed framework with two experimental datasets in real-world. As a result of comparative experiments, it was shown that the proposed framework was superior in terms of MAE, MSE, and MSLE.

• Composites Research
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• v.34 no.6
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• pp.357-372
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• 2021

The energy harvesting device is known to be promising as an alternative to solve the resource shortage caused by the depletion of petroleum resources. In order to overcome the limitations (environmental pollution and low mechanical properties) of piezoelectric elements capable of converting mechanical motion into electrical energy, many studies have been conducted on a polymer matrix-based composite piezoelectric energy harvesting device. In this paper, the output performance and related applications of the reported piezoelectric composites are reviewed based on the applied materials and processes. As for the piezoelectric fillers, zinc oxide, which is advantageous in terms of eco-friendliness, biocompatibility, and flexibility, as well as ceramic fillers based on lead zirconate titanate and barium titanate, were reviewed. The polymer matrix was classified into piezoelectric polymers composed of polyvinylidene fluoride and copolymers, and flexible polymers based on epoxy and polydimethylsiloxane, to discuss piezoelectric synergy of composite materials and improvement of piezoelectric output by high external force application, respectively. In addition, the effect of improving the conductivity or the mechanical properties of composite material by the application of a metal or carbon-based secondary filler on the output performance of the piezoelectric harvesting device was explained in terms of the structure of the composite material. Composite material-based piezoelectric harvesting devices, which can be applied to small electronic devices, smart sensors, and medicine with improved performance, can provide potential insights as a power source for wireless electronic devices expected to be encountered in future daily life.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.6
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• pp.1013-1022
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• 2022

Recently, with the worldwide development of the fourth industry, the development of technologies for smart and eco-friendly ships is accelerating. With the emergence of autonomous vessels with complete unmanned or minimum personnel on board and eco-friendly fuel (methane, ammonia, electricity, etc.), the role of existing seafarers on board is expected to change significantly. To improve the competitiveness of seafarers in the future, predicting future seafarer occupation groups, improving the educational curriculum, and creating an educational system are necessary. In this study, eight occupational groups that seafarers may have in the future were derived through a review of earlier studies and brainstorming of maritime university students, incumbent seafarers and expert groups. A survey was conducted on the eight occupational groups using the Likert scale, and based on the results, a leading occupational group related to future seafarer was derived. The most likely occupational groups with high scores were remote control centre operators and cargo remote manager. In addition, essential educational elements to be educated first for these occupational groups were derived and presented.

• Environmental and Resource Economics Review
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• v.31 no.3
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• pp.419-449
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• 2022

This paper aims to quantify the potential economic burdens of EU's carbon border adjustment mechanisms faced by Korean domestic industries. In addition, this study tries to compare and analyzes changes in the burden of each industry resulted from the implementation of the domestic low-carbon policy. Based on the quantitative findings, we intend to suggest policy implications for establishing mid- to long-term strategies in response to climate change risks. Based on the environmentally extended input-output analysis, the total economic burdens of the domestic industries due to the EU's carbon border adjustment mechanisms are estimated to be approximately KRW 8,245.6 billion in 2030. Looking at the impacts by industry, it is found that major industries such as petrochemicals, petroleum refining, transportation equipment, steel, automobiles, and electric/electronic equipment industries are expected to account for 84.3% of the total potential burdens. In addition, in multiple policy scenarios assuming technological developments and energy transition following the implementation of domestic low-carbon policies, the total economic burden of carbon border adjustment is expected to decrease by about 11.7% to 15.0%. The main result of this study suggests that we should not view EU EU's carbon border adjustment mechanism as a trade regulation, but to use it as a momentum for more effective implementation of the low-carbon and energy transition strategies in the global carbon neural era.