• International Journal of Industrial Entomology and Biomaterials
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• 제9권2호
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• pp.235-239
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• 2004

Drosophila melanogaster heat shock protein 70 gene promoter (Dhsp70p) is widely used in transgenic insect to drive exogenous gene, and the homologous region 3 from Bombyx mori nucleopolyhedrovirus (BmNPVhr3) functions as an enhancer for several promoters. To test whether BmNPVhr3 can enhance the Dhsp70ps transcriptional activity, the reporter plasmids, which contain the Dhsp70p, the reporter $\beta$-galactosidase gene with SV40 terminator and BmNPVhr3 fragment, are constructed and transfected into the insect cell lines (Bm-N cells and Sf-21 cells) by lipofectin-mediated method. The results from the transient expression assay show that BmNPVhr3 significantly increases transcriptional activity of Dhsp70p both under the normal condition and under the heat-shock treatment, although the effects are significantly different between in Bm-N cells and in sf-21 cells. The enhancing behavior of BmNPVhr3 on the Dhsp70p is in an orientation-independent manner. Meanwhile, the effects of heat-shock treatment on Dhsp70p alone or Dhsp70p/BmNPVhr3 combination present no significant difference, indicating that BmNPVhr3 only enhances the transcriptional activity of Dhsp70p, but cant alter its characteristic of the response to the heat-shock stress. The above results suggest that the Dhsp70p/BmNPVhr3 combination is more effective one to drive exogenous gene for transgene or stable cell expression system in insects.

• 한국해양학회지:바다
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• 제8권2호
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• pp.203-209
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• 2003

본 연구에서는 해양탐사장비를 예인하는 예인케이블에 관한 3차원 동적해석을 수행하였다. 해양케이블에 관한 지배방정식 중에서 굽힘강성 성분도 포함되는 보다 일반적인 지배방정식을 사용하였으며, 지배방정식은 3차원 비선형, 연성방정식이다. 예인선박의 예인속도와 측면주사음탐기의 중량에 따라서 예인단에서 발생하는 장력을 추정하였으며, 임의의 시간에 대한 케이블의 전체형상을 추정하였다. 정적해석결과를 통하여 특정한 수심에서 해양탐사장비를 예인할 때 예인속도를 잘못 조절한다면 관측장비가 해저면 바닥에 닿아서 탐사장비를 손실할 수 있다는 것을 알 수 있었다. 다양한 예인속도에 따른 예인단에서 장력의 변화를 살펴보았는데, 이를 통하여 예인단 장력은 예인속도가 임계속도보다 클 때는 접선하중성분이 지배적이고 작을 때는 자중효과가 지배적으로 나타난다는 것을 알 수 있었다. 또한 속도가 변하는 천이영역에서는 장력의 피크가 나타났으며 이것은 케이블에 충격력 효과로 작용할 수 있으므로 예인선박 운용에 이를 잘 고려해야 할 것이다. 본 연구결과는 다양한 해양탐사장비의 예인문제에 적용할 수 있을 것이다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.680-685
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• 2008

The ejector is a simple device which can transport a low-pressure secondary flow by using a high-pressure primary flow. In general, it consists of a primary driving nozzle, a mixing section, and a diffuser. The ejector system entrains the secondary flow through a shear action generated by the primary jet. Until now, a large number of researches have been made to design and evaluate the ejector systems, where it is assumed that the ejector system has an infinite secondary chamber which can supply mass infinitely. However, in almost all of the practical applications, the ejector system has a finite secondary chamber implying steady flow can be possible only after the flow inside ejector has reached an equilibrium state after the starting process. To the authors' best knowledge, there are no reports on the starting characteristics of the ejector systems and none of the works to date discloses the detailed flow process until the secondary chamber flow reaches an equilibrium state. The objective of the present study is to investigate the starting process of an ejector-diffuser system. The present study is also planned to identify the operating range of ejector-diffuser systems where the steady flow assumption can be applied without uncertainty. The results obtained show that the one and only condition in which an infinite mass entrainment is possible is the generation of a recirculation zone near the primary nozzle exit. The flow in the secondary chamber attains a state of dynamic equilibrium at this point.

• 대한조선학회 특별논문집
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• 대한조선학회 2015년도 특별논문집
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• pp.50-55
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• 2015

Application of newly conceptualized Anti-Splash Devices designed for COT vent pipes were studied on a P/V valve located on the upper deck of an oil carrier vessel. Anti-Splash devices are used in the shipbuilding industry in order to avoid oil overflow and spray accidents caused by excess pressure and vacuum condition in the cargo oil tanks. These conditions are caused by the transverse and longitudinal sloshing forces that arise from ship motion during sea voyages. The main issue with existing Anti-Splash device model is flux at the outlet of the Anti-Splash Device, and so, new conceptual models for the Anti-Splash device were developed and compared to existing Anti-Splash device model using CFD analysis. Transient analysis was used to capture the flow and velocity of each model and a comparative analysis was performed between old and new-concept models. This data was used to determine the optimal design parameters in order to develop an optimized Anti-Splash Device. A Factory acceptance test was performed on the new-concept models in order to verify the performance and efficiency against their design requirements and other criterion. The final step performed was to apply the optimized Anti-Splash Device models for COT vent pipes to an actual vessel and verify performance through a seawater cargo operation during a sea voyage as per the ship owner's request. The patent for the aforementioned device was obtained by the Korean Intellectual property Office dated Dec. 18th,2014.

• 한국항공우주학회지
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• 제49권4호
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• pp.311-320
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• 2021

무인기용 터보제트엔진의 운전 중 발생하는 고장을 실시간으로 진단하기 위한 방안 및 성능 열화와 관련된 건정성 추정에 관해 연구하였다. 이를 위해서, 동적 열역학 가스경로해석을 통한 비선형 동특성 방정식으로부터 실시간 선형모델을 도출하였고, 연출된 운전상황과 고장 발생을 실시간으로 진단하기 위해 칼만필터와 가설 검증에 기초한 확률적 판단 기법을 적용하였다. 이 결과, 분명한 고장 검출과 분리 성능을 보임으로써 그 효용성을 확인하였다. 측정변수를 통한 건전성 추정과 관련하여, 실제 엔진 구성품의 성능 열화 추이를 모사하였고, 적응형 칼만필터를 적용하여 추정 기법의 타당성을 입증함으로써, 상태 기반 고장 진단 및 정비 기법에 효과적으로 사용될 수 있음을 보였다.

• 마이크로전자및패키징학회지
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• 제29권1호
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• pp.7-16
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• 2022

최근 자동차 산업은 친환경, 편리함, 안전성과 같은 키워드를 중심으로 기술 발전이 이뤄지면서 빠르게 변화하고 있다. 친환경에 대한 관심과 맞물려 그린 카(green car)가 이목을 끌고 사용자 편의를 위한 첨단 기술 및 기능을 갖춘 고성능 자동차가 시장에 출시되고 있다. 발전하는 차량 성능으로 인해서 이에 맞는 전장품의 개발 또한 필수적이다. 자동차용 전장품은 고온, 고습, 열충격, 진동, 오염 등 복합적인 환경에서 사용되기 때문에 여타 산업에 비해 높은 수준의 신뢰성 검증이 필요하다. 특히, 부품 내 접합부의 신뢰성을 확보하여 무리없이 기능을 수행하고 운전자의 안전을 보장하는 것이 핵심이다. 따라서 저자는 차량 전장품의 최근 동향을 살펴보고 신뢰성을 향상시킬 수 있는 접합 방법으로 솔더링, TLP 접합 및 소결접합을 소개하였다.

• Nuclear Engineering and Technology
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• 제54권1호
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• pp.49-60
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• 2022

Motivated by the high-resolution properties of high-order Weighted Essentially Non-Oscillatory (WENO) and flux limiter (FL) for steep-gradient problems and the robust convergence of Jacobian-free Newton-Krylov (JFNK) methods for nonlinear systems, the preconditioned JFNK fully implicit high-order WENO and FL schemes are proposed to solve the transient two-phase two-fluid models. Specially, the second-order fully-implicit BDF2 is used for the temporal operator and then the third-order WENO schemes and various flux limiters can be adopted to discrete the spatial operator. For the sake of the generalization of the finite-difference-based preconditioning acceleration methods and the excellent convergence to solve the complicated and various operational conditions, the random vector instead of the initial condition is skillfully chosen as the solving variables to obtain better sparsity pattern or more positions of non-zero elements in this paper. Finally, the WENO_JFNK and FL_JFNK codes are developed and then the two-phase steep-gradient problem, phase appearance/disappearance problem, U-tube problem and linear advection problem are tested to analyze the convergence, computational cost and efficiency in detailed. Numerical results show that WENO_JFNK and FL_JFNK can significantly reduce numerical diffusion and obtain better solutions than traditional methods. WENO_JFNK gives more stable and accurate solutions than FL_JFNK for the test problems and the proposed finite-difference-based preconditioning acceleration methods based on the random vector can significantly improve the convergence speed and efficiency.

• Archives of Plastic Surgery
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• 제49권2호
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• pp.227-239
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• 2022

Complications experienced during lymphatic surgery have not been ubiquitously reported, and little has been described regarding how to prevent them. We present a review of complications reported during the surgical management of lymphedema and our experience with technical considerations to reduce morbidity from lymphatic surgery. A comprehensive search across different databases was conducted through November 2020. Based on the complications identified, we discussed the best approach for reducing the incidence of complications during lymphatic surgery based on our experience. The most common complications reported following lymphovenous anastomosis were re-exploration of the anastomosis, venous reflux, and surgical site infection. The most common complications using groin vascularized lymph node transfer (VLNT), submental VLNT, lateral thoracic VLNT, and supraclavicular VLNT included delayed wound healing, seroma and hematoma formation, lymphatic fluid leakage, iatrogenic lymphedema, soft-tissue infection, venous congestion, marginal nerve pseudoparalysis, and partial flap loss. Regarding intra-abdominal lymph node flaps, incisional hernia, hematoma, lymphatic fluid leakage, and postoperative ileus were commonly reported. Following suction-assisted lipectomy, significant blood loss and transient paresthesia were frequently reported. The reported complications of excisional procedures included soft-tissue infections, seroma and hematoma formation, skin-graft loss, significant blood loss, and minor skin flap necrosis. Evidently, lymphedema continues to represent a challenging condition; however, thorough patient selection, compliance with physiotherapy, and an experienced surgeon with adequate understanding of the lymphatic system can help maximize the safety of lymphatic surgery.

• Nuclear Engineering and Technology
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• 제54권5호
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• pp.1549-1559
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• 2022

As an accident tolerant fuel (ATF) concept, oxide dispersion strengthened Zircaloy-4 (ODS Zry-4) cladding has been developed to enhance the mechanical properties of cladding using laser processing technology. In this study, a simulation technique was established to investigate the mechanical properties and effects of Y₂O₃ particles for the ODS Zry-4. A 3D representative volume element (RVE) model was developed considering the parameters of the size, shape, distribution and volume fraction (VF) of the Y₂O₃ particles. From the 3D RVE model, the Young's modulus, coefficient of thermal expansion (CTE) and creep strain rate of the ODS Zry-4 were effectively calculated. It was observed that the VF of Y₂O₃ particles had a significant effect on the aforementioned mechanical properties. In addition, the predicted properties of ODS Zry-4 were applied to a simulation model to investigate cladding deformation under a transient condition. The ODS Zry-4 cladding showed better performance, such as a delay in large deformation compared to Zry-4 cladding, which was also found experimentally. Accordingly, it is expected that the simulation approach developed here can be efficiently employed to predict more properties and to provide useful information with which to improve ODS Zry-4.

• Nuclear Engineering and Technology
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• 제52권12호
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• pp.2743-2759
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• 2020

A detailed computational fluid dynamics (CFD) simulation analysis model was developed using ANSYS CFX 16.1 and analyzed to simulate the basic design and internal flow characteristics of a 180 MW small modular reactor (SMR) with a natural circulation flow system. To analyze the natural circulation phenomena without a pump for the initial flow generation inside the reactor, the flow characteristics were evaluated for each output assuming various initial powers relative to the critical condition. The eddy phenomenon and the flow imbalance phenomenon at each output were confirmed, and a flow leveling structure under the core was proposed for an optimization of the internal natural circulation flow. In the steady-state analysis, the temperature distribution and heat transfer speed at each position considering an increase in the output power of the core were calculated, and the conceptual design of the SMR had a sufficient thermal margin (31.4 K). A transient model with the output ranging from 0% to 100% was analyzed, and the obtained values were close to the T_hot and T_cold temperature difference value estimated in the conceptual design of the SMR. The K-factor was calculated from the flow analysis data of the CFX model and applied to an analysis model in RELAP5/MOD3.3, the optimal analysis system code for nuclear power plants. The CFX analysis results and RELAP analysis results were evaluated in terms of the internal flow characteristics per core output. The two codes, which model the same nuclear power plant, have different flow analysis schemes but can be used complementarily. In particular, it will be useful to carry out detailed studies of the timing of the steam generator intervention when an SMR is activated. The thermal and hydraulic characteristics of the models that applied porous media to the core & steam generators and the models that embodied the entire detail shape were compared and analyzed. Although there were differences in the ability to analyze detailed flow characteristics at some low powers, it was confirmed that there was no significant difference in the thermal hydraulic characteristics' analysis of the SMR system's conceptual design.