• 한국어류학회지
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• 제36권2호
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• pp.156-163
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• 2024

본 연구는 동해 울진 연안 10개 정점에서 계절별(2022년 4월, 7월, 10월, 2023년 2월)로 Ring net를 이용하여 채집한 자치어 종조성의 계절변동을 조사하였다. 총 27개 분류군에 속하는 자치어가 채집되었다. 어류 자치어 우점종은 참가자미(Pseudopleuronectes herzensteini), 볼락(Sebastes inermis), 까나리(Ammodytes japonicus), 문치가자미(Pseudopleuronectes yokohamae), 그물코쥐치 (Rudarius ercodes), 청베도라치(Parablennius yatabei)였고 상기 6종은 전체 자치어 현존량의 86.6%를 차지하였다. 자치어 출현종수, 현존량, 다양도지수는 계절에 따라 변하였는데, 출현종수와 현존량은 4월(춘계)에 가장 높았고, 다양도지수는 7월(하계)에 가장 높았다. 조사해역에서 자치어 군집의 계절별 출현양상에 따라 춘계, 하계, 동계 그룹을 구분할 수 있었다. 우점종 중 참가자미는 춘계에 우점하였고, 청베도라치와 그물코쥐치는 하계에 우점하였다. 그리고 볼락, 까나리, 문치가자미는 동계에 현존량이 높았다. 이러한 자치어 군집의 시간적 변동은 계절에 따른 수온 차이에 영향을 받았던 것으로 판단된다. 본 연구 결과는 동해에서 어류 자치어 다양성을 밝히고 연안해역의 산란장 기능을 평가하는 데 기여할 것으로 생각된다.

• Imaging Science in Dentistry
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• 제54권1호
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• pp.81-91
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• 2024

Purpose: The objective of this study was to propose a deep-learning model for the detection of the mandibular canal on dental panoramic radiographs. Materials and Methods: A total of 2,100 panoramic radiographs (PANs) were collected from 3 different machines: RAYSCAN Alpha (n=700, PAN A), OP-100 (n=700, PAN B), and CS8100 (n=700, PAN C). Initially, an oral and maxillofacial radiologist coarsely annotated the mandibular canals. For deep learning analysis, convolutional neural networks (CNNs) utilizing U-Net architecture were employed for automated canal segmentation. Seven independent networks were trained using training sets representing all possible combinations of the 3 groups. These networks were then assessed using a hold-out test dataset. Results: Among the 7 networks evaluated, the network trained with all 3 available groups achieved an average precision of 90.6%, a recall of 87.4%, and a Dice similarity coefficient (DSC) of 88.9%. The 3 networks trained using each of the 3 possible 2-group combinations also demonstrated reliable performance for mandibular canal segmentation, as follows: 1) PAN A and B exhibited a mean DSC of 87.9%, 2) PAN A and C displayed a mean DSC of 87.8%, and 3) PAN B and C demonstrated a mean DSC of 88.4%. Conclusion: This multi-device study indicated that the examined CNN-based deep learning approach can achieve excellent canal segmentation performance, with a DSC exceeding 88%. Furthermore, the study highlighted the importance of considering the characteristics of panoramic radiographs when developing a robust deep-learning network, rather than depending solely on the size of the dataset.

• Nuclear Engineering and Technology
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• 제55권11호
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• pp.4274-4281
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• 2023

Blanket is of vital importance for engineering application of the fusion reactor. Nuclear heat deposition in materials is the main heat source in blanket structure. In this paper, the three-dimensional method for thermal-hydraulics/neutronics coupling analysis is developed and applied for the full-scale module of the helium-cooled ceramic breeder tritium breeding blanket (HCCB TBB) designed for China Fusion Engineering Test Reactor (CFETR). The explicit coupling scheme is used to support data transfer for coupling analysis based on cell-to-cell mapping method. The coupling algorithm is realized by the user-defined function compiled in Fluent. The three-dimensional model is established, and then the coupling analysis is performed using the paralleled Coupling Analysis of Thermal-hydraulics and Neutronics Interface Code (CATNIC). The results reveal the relatively small influence of the coupling analysis compared to the traditional method using the radial fitting function of internal heat source. However, the coupling analysis method is quite important considering the nonuniform distribution of the neutron wall loading (NWL) along the poloidal direction. Finally, the structure optimization of the blanket is carried out using the coupling method to satisfy the thermal requirement of all materials. The nonlinear effect between thermal-hydraulics and neutronics is found during the blanket structure optimization, and the tritium production performance is slightly reduced after optimization. Such an adverse effect should be thoroughly evaluated in the future work.

• Nuclear Engineering and Technology
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• 제55권11호
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• pp.3940-3955
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• 2023

A new method of numerical simulating prediction and decontamination effect evaluation for abrasive jet decontamination to radioactively contaminated metal is proposed. Based on the Computational Fluid Dynamics and Discrete Element Model (CFD-DEM) coupled simulation model, the motion patterns and distribution of abrasives can be predicted, and the decontamination effect can be evaluated by image processing and recognition technology. The impact of three key parameters (impact distance, inlet pressure, abrasive mass flow rate) on the decontamination effect is revealed. Moreover, here are experiments of reliability verification to decontamination effect and numerical simulation methods that has been conducted. The results show that: ⁶⁰Co and other homogeneous solid solution radioactive pollutants can be removed by abrasive jet, and the average removal rate of Co exceeds 80%. It is reliable for the proposed numerical simulation and evaluation method because of the well goodness of fit between predicted value and actual values: The predicted values and actual values of the abrasive distribution diameter are Ф57 and Ф55; the total coverage rate is 26.42% and 23.50%; the average impact velocity is 81.73 m/s and 78.00 m/s. Further analysis shows that the impact distance has a significant impact on the distribution of abrasive particles on the target surface, the coverage rate of the core area increases at first, and then decreases with the increase of the impact distance of the nozzle, which reach a maximum of 14.44% at 300 mm. It is recommended to set the impact distance around 300 mm, because at this time the core area coverage of the abrasive is the largest and the impact velocity is stable at the highest speed of 81.94 m/s. The impact of the nozzle inlet pressure on the decontamination effect mainly affects the impact kinetic energy of the abrasive and has little impact on the distribution. The greater the inlet pressure, the greater the impact kinetic energy, and the stronger the decontamination ability of the abrasive. But in return, the energy consumption is higher, too. For the decontamination of radioactively contaminated metals, it is recommended to set the inlet pressure of the nozzle at around 0.6 MPa. Because most of the Co elements can be removed under this pressure. Increasing the mass and flow of abrasives appropriately can enhance the decontamination effectiveness. The total mass of abrasives per unit decontamination area is suggested to be 50 g because the core area coverage rate of the abrasive is relatively large under this condition; and the nozzle wear extent is acceptable.

• Nuclear Engineering and Technology
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• 제55권12호
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• pp.4447-4464
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• 2023

This paper focuses on the development of a new computational model of the CNESTEN's TRIGA Mark II research reactor using the 3D continuous energy Monte-Carlo code TRIPOLI-4 (T4). This new model was developed to assess neutronic simulations and determine quantities of interest such as kinetic parameters of the reactor, control rods worth, power peaking factors and neutron flux distributions. This model is also a key tool used to accurately design new experiments in the TRIGA reactor, to analyze these experiments and to carry out sensitivity and uncertainty studies. The geometry and materials data, as part of the MCNP reference model, were used to build the T4 model. In this regard, the differences between the two models are mainly due to mathematical approaches of both codes. Indeed, the study presented in this article is divided into two parts: the first part deals with the development and the validation of the T4 model. The results obtained with the T4 model were compared to the existing MCNP reference model and to the experimental results from the Final Safety Analysis Report (FSAR). Different core configurations were investigated via simulations to test the computational model reliability in predicting the physical parameters of the reactor. As a fairly good agreement among the results was deduced, it seems reasonable to assume that the T4 model can accurately reproduce the MCNP calculated values. The second part of this study is devoted to the sensitivity and uncertainty (S/U) studies that were carried out to quantify the nuclear data uncertainty in the multiplication factor k_eff. For that purpose, the T4 model was used to calculate the sensitivity profiles of the k_eff to the nuclear data. The integrated-sensitivities were compared to the results obtained from the previous works that were carried out with MCNP and SCALE-6.2 simulation tools and differences of less than 5% were obtained for most of these quantities except for the C-graphite sensitivities. Moreover, the nuclear data uncertainties in the k_eff were derived using the COMAC-V2.1 covariance matrices library and the calculated sensitivities. The results have shown that the total nuclear data uncertainty in the k_eff is around 585 pcm using the COMAC-V2.1. This study also demonstrates that the contribution of zirconium isotopes to the nuclear data uncertainty in the k_eff is not negligible and should be taken into account when performing S/U analysis.

• 자원ㆍ환경경제연구
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• 제33권2호
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• pp.113-133
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• 2024

태양광과 풍력을 중심으로 한 변동성 재생발전(VRE)은 탄소중립 달성의 주요수단이지만 높은 변동성과 불확실성으로 인해 전력공급의 안정성을 훼손시킨다. 에너지저장장치(ESS)는 수요이전을 통해 재생발전의 출력제한을 경감시킬 뿐만아니라 보조서비스 제공을 통해 안정적인 전력시스템 운영에 기여할 수 있다. 본 연구는 VRE로 인한 문제점이 점점 본격화되는 상황에서 ESS자원을 수요이전 기능과 예비력 제공기능 간에 어떻게 분배하는 것이 전력공급 효율성 최대화에 기여할 수 있는지 분석한다. 분석모형으로 재생발전의 변동성과 불확실성을 현실적으로 모의할 수 있는 확률적 전력시스템 최적화 모형을 적용하였다. 분석시점은 2023년과 2036년으로 설정하여 재생발전 보급수준별 ESS 최적자원분배 전략과 편익을 분석하였다. 분석결과는 크게 다음의 3가지로 요약가능하다. 첫째, ESS는 수요이전과 예비력 제공 모두에 탁월한 기능을 제공하며, 예비력 가격이 높게 설정될수록 수요이전 기능은 제한하고 예비력 제공에 집중함을 확인할 수 있었다. 둘째, 재생발전 출력제한은 필요예비력에 대한 대체재 역할을 하며, 예비력 가격 수준이 높아질수록 출력제한은 증가하고 필요예비력은 감소하는 것이 비용 합리적이다. 셋째, 기회비용이 반영된 합리적인 예비력 가격이 적용될 경우 ESS는 가까운 미래에 경제성을 확보할 수 있으며, ESS의 경제성은 재생발전 비중이 높을수록 더 커짐을 확인할 수 있었다. 본 연구는 전력공급 자원이 효율적으로 분배될 수 있는 가격기능이 바로 설때 비용 효율적인 전력부문 저탄소 전환이 가능함을 시사한다.

• 한국초지조사료학회지
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• 제44권2호
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• pp.92-98
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• 2024

본 연구는 수입산 알팔파와 열풍 건조 국내산 알팔파를 이용한 TMR의 혼합 급여가 착유우의 우유 생산량, 유질 및 반추 시간 비교 분석 등을 통해 열풍 건조 국내산 알팔파의 사료가치 평가를 수행하였다. 두 종류의 알팔파 내 TDN, NE_L 및 체중은 차이를 보이지 않았고, 사료 섭취량은 열풍 건조 국내산 알팔파의 TMR 혼합 급여구에서 높았으며, 반추 활동 시간은 차이를 보이지 않았다. 우유생산량, 유지방과 유단백질 함량, FPCM, FE 및 SCC는 차이를 보이지 않았으며, 유지방 생산량과 lactose 함량은 열풍 건조 국내산 알팔파 TMR 혼합 급여구에서 높았다. 따라서 본 연구에서 이용된 열풍 건조 국내산 알팔파와 TMR의 혼합 급여는 착유우의 사료 섭취량, 반추 활동 및 생산성에 차이를 보이지 않았으므로, 열풍 건조 국내산 알팔파를 수입산 알팔파로 대체하여 착유우에게 이용될 수 있을 것으로 사료된다.

• 환경생물
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• 제42권2호
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• pp.193-206
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• 2024

본 연구는 한반도 전체 산림면적과 탄소저장량의 변화를 추정하기 위해 수행되었다. 위성영상을 활용하여 2000~2019년 기간 산림면적의 변화를 연도별로 분석하였으며, 한국형 산림탄소모형을 기반으로 2000~2020년의 산림탄소 변화를 추정하였다. 모형의 검증을 위해 국가산림자원조사 자료와 임업통계연보, European Space Agency (ESA)에서 구축한 산림 바이오매스 지도를 활용하였다. Landsat 위성자료를 기반으로 한 한반도 산림손실 면적은 478,334 ha로 추정되었으며, 북한과 남한은 각각 48.6% (232,610 ha)와 51.3% (245,725 ha)의 총 손실 면적을 차지하여 지난 20년간 북한과 남한이 비슷한 면적의 산림이 손실된 것이 확인되었다. 모델 분석 결과 2000년의 우리나라와 북한 산림의 지상부 탄소저장량은 211.5, 277.1 Tg C으로 추정되었으며, 2020년에는 각각 357.9, 417.4 Tg C으로 증가할 것으로 나타났다. 같은 기간 우리 나라와 북한 산림의 단위면적당 평균 탄소저장량은 각각 34.8, 29.4 Mg C ha^-1에서 58.9, 44.2 Mg C ha^-1으로 증가할 것으로 분석되었으며, 이러한 결과는 우리나라 산림이 북한의 산림보다 전반적인 생산성과 탄소흡수량이 높다는 것을 의미한다. 또한, ESA의 분석 결과에서 우리나라의 산림 바이오매스가 다소 낮게 추정된 것이 확인되었으며, 따라서 앞으로 보다 활발한 연구와 정보공유 등을 통해 국제사회 및 학문의 영역에서 우리나라 산림의 평가가 제고될 필요성이 있다고 사료된다. 본 연구 결과는 한반도 전체 산림 탄소 및 자원의 추정에 행정구역 및 국가 단위의 유용한 정보를 제공할 뿐만 아니라, 향후 북한 산림환경복구 계획수립을 위한 기초자료로 활용될 수 있을 것으로 기대된다.

• Nuclear Engineering and Technology
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• 제56권7호
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• pp.2875-2880
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• 2024

The development of nuclear power plants is in three phases. The first phase is a consideration before the decision on the NPP construction program is approved, the second phase is the preparatory work for making contracts and preparing for the construction of NPP after the NPP construction policy is approved, and the third phase is contracting, licensing and building the first NPP. As a volcanically active country, Indonesia contains over 130 active volcanoes that are part of the Pacific Ring of Fire. The volcanic aspect is one of the safety factors considered while deciding the location of an NPP. Research on the potential of natural external risks to the determination of nuclear power plants in Indonesia, including the volcanic aspect, has been conducted based on the safety reference or safety guide of the IAEA and the Nuclear Energy Regulatory Body (BAPETEN) Regulation. Due to technological advancements, safety needs have evolved so the existing Indonesia National Standard (SNI) must be updated to comply with BAPETEN regulations. The substance in SNI 18-2034-1990 relating to volcanic features seems less relevant in actual conditions, given that more complete and exact criteria for determining a site guarantee the safety and health of residents and surrounding the environment site. The study intends to conduct a gap analysis of volcanic issues in SNI and volcanic regulations. The method used is identification requirements for volcanic aspects in SNI 18-2034-1990 about Determining Site of Nuclear Reactor Guidance with BAPETEN Chairman Regulation (BCR) number 4 of 2018 about Nuclear Installation Site Evaluation Safety Provisions and BCR number 5 of 2015 about Evaluation of Nuclear Installation Sites for Volcanic Aspects, and analysis uses a qualitative method of inductive techniques. The outcome of this research applies to suggesting a revision of SNI number 18-2034-1990, especially the volcanic aspect.

• Nuclear Engineering and Technology
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• 제56권7호
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• pp.2799-2805
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• 2024

Energy-resolved neutron imaging is an effective way to investigate the internal structure and residual stress of materials. Different sample sizes have varying requirements for the detector's imaging field of view (FOV) and spatial resolution. Therefore, a dual-mode energy-resolved neutron imaging detector was developed, which mainly consisted of a neutron scintillator screen, a mirror, imaging lenses, and a time-stamping optical fast camera. This detector could operate in a large FOV mode or a high spatial resolution mode. To evaluate the performance of the detector, the neutron wavelength spectra and the multiple spatial resolution tests were conducted at CSNS. The results demonstrated that the detector accurately measured the neutron wavelength spectra selected by a bandwidth chopper. The best spatial resolution was about 20 ㎛ in high spatial resolution mode after event reconstruction, and a FOV of 45.0 mm × 45.0 mm was obtained in large FOV mode. The feasibility was validated to change the spatial resolution and FOV by replacing the scintillator screen and adjusting the lens magnification.