• Animal Bioscience
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• 제35권2호
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• pp.260-271
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• 2022

Objective: We aimed to investigate the effect of the differing amino acid (AA) release dynamics of two protein sources on the growth performance, nitrogen deposition, plasma biochemical parameters, and muscle synthesis and degradation of piglets when included in their diets at normal and low concentrations. Methods: Forty-eight piglets (Duroc×Landrace×Large White) with initial body weight of 7.45±0.58 kg were assigned to six groups and fed one of 6 diets. The 6 dietary treatments were arranged by 3×2 factorial with 3 protein sources and 2 dietary protein levels. They are NCAS (a normal protein content with casein), NBlend (a normal protein content with blend of casein and corn gluten meal), NCGM (a normal protein content with corn gluten meal), LCAS (a low protein content with casein), LBlend (a low protein content with blend of casein and corn gluten meal), LCGM (a low protein content with corn gluten meal). The release dynamics of AA in these diets were determined by in vitro digestion. The digestibility, utilization and biological value of nitrogen in piglets were determined by micro Kjeldahl method. Plasma insulin was measured by enzyme-linked immunosorbent assay kits. The protein expression of mediators of muscle synthesis and degradation was determined by western blotting. Results: Although the consumption of a low-protein diet supplemented with crystalline AA was associated with greater nitrogen digestion and utilization (p<0.05), the final body weight, growth performance, nitrogen deposition, and phosphorylation of ribosomal protein S6 kinase 1 and eIF4E binding protein 1 in the muscle of pigs in the low-protein diet-fed groups were lower than those of the normal-protein diet-fed groups (p<0.05) because of the absence of non-essential AA. Because of the more balanced release of AA, the casein (CAS) and Blend-fed groups showed superior growth performance, final body weight and nitrogen deposition, and lower expression of muscle ring finger 1 and muscle atrophy F-box than the CGM-fed groups (p<0.05). Conclusion: We conclude that the balanced release of AA from CAS containing diets and mixed diets could reduce muscle degradation, favor nitrogen retention, % intake and improve growth performance in pigs consuming either a normal- or low-protein diet.

• International Journal of Fluid Machinery and Systems
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• 제5권3호
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• pp.100-108
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• 2012

Design parameters for suction channels of process centrifugal compressors were investigated, and an optimization method to enhance stage efficiency by using the new design parameters was proposed. From results of computational fluid dynamics, the passage sectional area ratios $A_c/A_e$, $A_e/A_s$ and $A_c/A_s$ were found to be the dominant parameters for the pressure loss and circumferential flow distortion, where $A_c$, $A_e$ and $A_s$ are passage sectional areas for the casing upstream side, casing entrance and impeller eye, respectively. The Base suction channel was optimized using the new design parameters, and the Base and Optimized types were tested. Test results showed that the Optimized suction channel achieved 3.8% higher stage efficiency than the Base suction channel while maintaining the same operating range.

• 생명과학회지
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• 제33권11호
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• pp.851-858
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• 2023

Unique cartilage matrix-associated protein (UCMA)은 γ-카르복실화(Gla) 잔기가 풍부한 간외 비타민 K 의존 단백질이다. UCMA는 조골세포 분화를 촉진하고 뼈 형성을 강화한다고 보고되고 있지만 고혈당 스트레스 하에서 조골세포에 미치는 영향에 대해서는 아직 알려진 바가 없다. 본 연구에서는 고혈당 조건하에서의 MC3T3-E1 조골세포에서 UCMA 효과를 조사하기 위해 MC3T3-E1 조골세포를 높은 포도당에 노출한 후 재조합 UCMA 단백질을 처리하였다. MC3T3-E1 세포에서 활성 산소종(ROS)의 생성은 고혈당 조건하에서 증가했으나 UCMA 단백질 처리 후 감소했음을 CellROX 및 MitoSOX 염색으로 확인하였다. 또한 고혈당 조건에서 UCMA 단백질을 함께 처리한 MC3T3-E1 세포에서 정량적 중합효소 연쇄반응 결과, 항산화 유전자인 nuclear factor erythroid 2-related factor 2 와 superoxide dismutase 1 발현이 증가하였다. 동일 조건하에서 UCMA 단백질 처리에 의해 heme oxygenase-1 발현 감소와 함께 세포질에서 핵으로의 전위가 감소되었고, 미토콘드리아 분열에 관여하는 dynamin-related protein 1 발현이 증가하였으며, AKT 신호 활성은 억제되었다. 종합적으로 UCMA는 고혈당에 노출된 조골세포에서 ROS 생성을 완화하고, 항산화 유전자 발현을 증가시키고, 미토콘드리아 역학에 영향을 미치며, AKT 신호를 조절하는 것으로 보인다. 본 연구는 UCMA의 세포 메커니즘에 대한 이해를 돕고, 대사 장애 관련한 골 합병증에 대한 새로운 치료제로서의 잠재적 사용 가능성을 제시하고 있다.

• 한국어류학회지
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• 제9권1호
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• pp.141-152
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• 1997

1995년 9월부터 1996년 8월까지 팔당호의 어류군집 동태를 조사한 결과는 다음과 같다. 채집된 어류는 총 11과 42종, 9,101개체였으며 우점종은 Erythroculter erythropterus(상대풍부도 : 27.96%), 아우점종은 Lepomis macrochirus(20.69%)였고 우세종은 Squalidus japonicus coreunus(19.25%), Opsariichthys bidens(4.07%), Hemibarbus labeo(3.42%), Acheilognathus yamatsutae(2.68%), Micropterus salmoides(2.68%) 등이었다. 계절별 우점종은 춘계에는 L. macrochirus(23.75%)였고 하계에는 S. japonicus coreanus(33.88%), 추계에는 L. macrochirus(41.59%)였으며 E. erythropterus가 전 계절에 걸쳐 아우점종으로 나타났다. 댐 축조 후 팔당호의 어류상은 정수성으로 변화하였으며, 한국 고유종은 10종으로 전체 채집 어종의 23.8%를 차지하였다. 외래 도입 어종은 4종이었으며 개체수에 대한 상대풍부도는 24.75%에 달하였다. 각 지점별 군집분석 결과 족대와 투망 채집에서 우점도는 지점 2가 0.78로 가장 높았으며 종다양도는 지점 5가 2.52, 종풍부도는 지점 4가 3.66, 균등도는 지점 5가 0.91로 가장 높게 나타났고 정치망 채집에서 우점도는 지점 8이 0.87, 종다양도는 지점 14가 1.91, 종풍부도는 지점 7이 2.80, 균등도는 지점 14가 0.72로 가장 높게 나타났다. 우세종의 개체군 연령 구조 분석 결과 E. erythropterus의 연령 구조는 매우 안정되어 있었으며 L. macrochirus는 3~4년생의 개체군이 주로 채집되었다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제2권3호
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• pp.139-145
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• 2010

In the present study, we conducted resistance test, propeller open water test and self-propulsion test for a ship's resistance and propulsion performance, using computational fluid dynamics techniques, where a Reynolds-averaged Navier-Stokes equations solver was employed. For convenience of mesh generation, unstructured meshes were used in the bow and stern region of a ship, where the hull shape is formed of delicate curved surfaces. On the other hand, structured meshes were generated for the middle part of the hull and the rest of the domain, i.e., the region of relatively simple geometry. To facilitate the rotating propeller for propeller open water test and self-propulsion test, a sliding mesh technique was adopted. Free-surface effects were included by employing the volume of fluid method for multi-phase flows. The computational results were validated by comparing with the existing experimental data.

• 방사성폐기물학회지
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• 제18권3호
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• pp.363-372
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• 2020

Anionic radionuclides pose one of the highest risks to the long-term safety assessments of disposal repositories. Therefore, techniques to immobilize and separate such anionic radionuclides are of crucial importance from the viewpoints of safety and waste volume reduction. The main objective of this study is to design a separator with minimum pressure disturbance, based on the concept of a conventional cyclone separator. We hypothesize that the anionic radionuclides can be immobilized onto a nanomaterial-based substrate and that the particles generated in the process can flow via water. These particles are denser than water; hence, they can be trapped within the cyclone-type separator because of its design. We conducted particle tracking analysis using computational fluid dynamics (CFD) for the conventional cyclone separator and studied the effects due to the morphology of the separator. The proposed sandglass-like design of the separator shows promising results (i.e., only one out of 10,000 particles escaped to the outlet from the separation zone). To validate the design, we manufactured a laboratory-scale prototype separator and tested it for iron particles; the efficiency was ca. 99%. Furthermore, using an additional magnetic effect with the separator, we could effectively separate particles with ~100% efficiency. The proposed sandglass-like separator can thus be used for effective separation and recovery of immobilized anionic radionuclides.

• 해양환경안전학회지
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• 제28권3호
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• pp.441-450
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• 2022

The introduction of autonomous underwater gliders (AUGs) specifically addresses the reduction of operational costs that were previously prohibited with conventional autonomous underwater vehicles (AUVs) using a "scaling-down" design philosophy by utilizing the characteristics of autonomous drifters to far extend operation duration and coverage. Long-duration, wide-area missions raise the cost and complexity of in-water testing for novel approaches to autonomous mission planning. As a result, a simulator that supports the rapid design, development, and testing of autonomy solutions across a wide range using software-in-the-loop simulation at faster-than-real-time speeds becomes critical. This paper describes a faster-than-real-time AUG simulator that can support high-resolution bathymetry for a wide variety of ocean environments, including ocean currents, various sensors, and vehicle dynamics. On top of the de facto standard ROS-Gazebo framework and open-sourced underwater vehicle simulation packages, features specific to AUGs for ocean mapping are developed. For vehicle dynamics, the next-generation hybrid autonomous underwater gliders (Hybrid-AUGs) operate with both the buoyancy engine and the thrusters to improve navigation for bathymetry mappings, e.g., line trajectory, are is implemented since because it can also describe conventional AUGs without the thrusters. The simulation results are validated with experiments while operating at 120 times faster than the real-time.

• 한국광물학회지
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• 제29권4호
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• pp.209-220
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• 2016

점토광물은 대기부터 지하수에 이르는 크리티컬존(critical zone) 영역에서 금속과 탄소 순환을 결정짓는 역할을 한다. 계산광물학 연구방법 중에 하나인 분자동역학(molecular dynamics) 시뮬레이션은 지구물질을 원자단위로 계산하기 때문에, 점토광물의 물리화학적 현상들에 대해 원자수준의 자세한 정보를 제공할 수 있다. 이번 연구에서는 clayFF 힘 장(force field)을 사용한 분자동역학 시뮬레이션을 이팔면체 점토광물인 깁사이트(gibbsite, $Al(OH)_3$), 카올리나이트(kaolinite, $Al_2Si_2O_5(OH)_4$), 파이로필라이트(pyrophyllite, $Al_2Si_4O_{10}(OH)_2$)에 적용하여 300 K, 1기압조건에서 각 광물이 가지는 격자상수와 원자간 거리를 계산하고 실험결과와 비교하였다. 더불어 수산기의 방향성 및 수소결합의 양상 그리고 파워스펙트럼(power spectrum)을 추가적으로 계산하였다. 계산 결과, 격자상수는 기존의 실험결과와 약 0.1~3.7% 미만의 오차율을 보였으며, 원자간 거리는 실험결과와 약 5% 미만의 차이를 가졌다. 깁사이트나 카올리나이트의 팔면체층 표면에 존재하는 수산기가 가지는 신축진동파수(stretching vibrational wavenumber)는 실험값 보다 약 $200-300cm^{-1}$ 높게 계산되었지만, 팔면체층 표면에 존재하는 수산기들의 상대적 크기의 경향은 기존 실험 결과와 일치하였다. 팔면체층 표면의 수산기가 (001)면과 이루는 각도도 기존 실험결과와 상당부분 일치한 반면에 내부 수산기의 경우는 다소 차이를 보였다. ClayFF를 사용한 분자동역학 시뮬레이션 연구 방법은 이팔면체 점토광물 표면 내(층간) 금속이온 흡착에 대한 수산기의 역할을 규명하는데 유용한 연구방법이 될 수 있음을 시사한다.

• 한국태양에너지학회 논문집
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• 제27권3호
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• pp.117-125
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• 2007

This study proposes a CFD(Computational Fluid Dynamics) analysis as a method of verification of the designed-data and a supplement of the insufficient experiences in geothermal system, which shows a rapid growth among the renewable energies. The followings are the results. FLUENT 6.2.12 is used as a CFD tool on this study, with the equations of continuity, motion, energy for unsteady flow through pipes and k-epsilon turbulent model. S-type model which has one borehole with diameter 12m by depth 206m and T-type model which has 3 boreholes with $12m{\times}20m{\times}206m$ are proposed, and also the boundary conditions are described. The temperature differences between temperatures by CFD analysis and by on-site measurement are less than 1.5%, this shows a high reliability of CFD analysis process which this study proposes. After 11 days simulation operated 12 hours interval On/Off mode, it is clearly predicted that the outlet temperatures of geothermal pipes are increased by $1.2^{\circ}C$, and $2.2^{\circ}C$ after 4 months. And the outlet temperatures of geothermal pipes increased with increase of the mass flow rates through the pipes. T-type model shows that the 4m distance between boreholes are reasonable because the temperatures at 2m and 6m from boreholes are nearly same.

• 한국지하수토양환경학회지:지하수토양환경
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• 제17권6호
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• pp.23-32
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• 2012

This study was conducted to monitor microbial species dynamics within the aquifer due to long term operation of geothermal heat pump system. The species were identified by molecular biological methods of 16S rDNA. Groundwater sample was collected from both open (S region) and closed geothermal recovery system (J region) along with the control. J measured and control as well as S measured found Ralstonia pickettii as dominant species at year 2010. In contrast, Rhodoferax ferrireducens was dominantly observed for the control of S. In 2011, Sediminibacterium sp. was universely identified as the dominant species regardless of the monitoring places and type of sample, i.e., measured or control. The difference in the dynamics between the measured and the control was not critically observed, but annual variation was more strikingly found. It reveals that possible environmental changes (e.g. ORP and DO) due to the operation of geothermal heat recovery system in aquifer could be more exceedingly preceded to differentiate annual variation of microbial species rather than positional differences.