• Pediatric Gastroenterology, Hepatology & Nutrition
• /
• 제11권sup1호
• /
• pp.72-82
• /
• 2008

Wilson disease (WD) is an autosomal recessive disorder of copper metabolism that results in accumulation of copper primarily in the liver, the brain and the cornea. Mutations in the WD gene, ATP7B cause failure of copper excretion from hepatocyte into bile and a defective synthesis of ceruloplasmin. More than 370 mutations are now recognized, scattering throughout the ATP7B gene. Since WD has protean clinical presentations, awareness of WD in clinical practice is important for the early diagnosis and prevention of accumulated copper toxicity. None of the laboratory parameters alone allows a definite diagnosis of WD. There are numerous pitfalls in the diagnosis of WD. Low serum ceruloplasmin concentrations, increased 24 hour urinary copper excretion, increased hepatic copper concentrations and the presence of Kayser-Fleischer rings in the cornea are major diagnostic points. A combination of any two of these 4 laboratory findings is strong support for a diagnosis of WD. Molecular methods are now being used to aid diagnosis. Molecular genetic testing has confirmed the diagnosis in individuals in whom the diagnosis is not clearly established biochemically and clinically. Siblings should be screened for WD once an index case has been diagnosed. Discrimination of heterozygotes from asymptomatic patients is essential to avoid inappropriate lifelong therapy for heterozygotes. Genetic testing, either by haplotype analysis or by mutation analysis, is the only reliable tool for differentiating heterozygote carriers from affected asymptomatic patients. Currently, genetic testing is of limited value in the primary diagnosis. However, genetic testing will soon play an essential role in diagnosing WD as rapid advancement of biomedical technology will allow more rapid, easier and less expensive mutation detection.

• 한국정밀공학회지
• /
• 제28권6호
• /
• pp.709-715
• /
• 2011

Chattering in cutting operations are usually a cumbersome part of the manufacturing process in mechanical. Particular, machining performance such as that of the boring process is limited by cutting condition at the movable components. Among various sources of chatter vibration, detrimental point in cutting condition is found a mechanical condition on overhang. It limits cutting speed, depth, surface roughness and tool wear failure as result because the all properties are varying with the metal removal process. In this case, we have to observe the resonance frequencies of a boring bar for continuous cutting. In the established research, boring bar vibration of cutting system has been measured with the aid of accelerometer. However, the inherent parameters of internal turning operations are severely limit for the real time monitoring on accelerometers. At this point, this paper is proposed other method for real time monitoring during continuous cutting with optical fiber at the inside of boring bar. This method has been used a plastic fiber in the special jig on boring bar by based on experimental modal analysis. In this study, improvement of monitoring system on continuous internal cutting was attempted using optical fiber sensor of inside type because usually chattering is investigated experimentally measuring the variation in chip thickness. It is demonstrated that the optical fiber sensor is possibility to measure of chattering with real time in boring process.

• Computers and Concrete
• /
• 제22권1호
• /
• pp.27-37
• /
• 2018

Reinforced concrete structures are widely used in civil engineering projects around the world in different designs. Due to the great evolution in computational equipment and numerical methods, structural analysis has become more and more reliable, and in turn more closely approximates reality. Thus among the many numerical methods used to carry out these types of analyses, the finite element method has been highlighted as an optimized tool option, combined with the non-linear and linear analysis techniques of structures. In this paper, the behavior of reinforced concrete beams was analyzed in two different configurations: i) with welding and ii) conventionally lashed stirrups using annealed wire. The structures were subjected to normal and tangential forces up to the limit of their bending resistance capacities to observe the cracking process and growth of the concrete structure. This study was undertaken to evaluate the effectiveness of welded wire fabric as shear reinforcement in concrete prismatic beams under static loading conditions. Experimental analysis was carried out in order compare the maximum load of both configurations, the experimental load-time profile applied in the first configuration was used to reproduce the same loading conditions in the numerical simulations. Thus, comparisons between the numerical and experimental results of the welded frame beam show that the proposed model can estimate the concrete strength and failure behavior accurately.

• Nuclear Engineering and Technology
• /
• 제32권4호
• /
• pp.395-409
• /
• 2000

Parametric studies were performed to assess the sensitivity in determining the maximum in-vessel heat removal capability from the core material relocated into the lower plenum of the reactor pressure vessel (RPV）during a core melt accident. A fraction of the sensible heat can be removed during the molten jet delivery from the core to the lower plenum, while the remaining sensible heat and the decay heat can be transported by rather complex mechanisms of the counter-current flow limitation (CCFL) and the critical heat flux (CHF）through the irregular, hemispherical gap that may be formed between the freezing oxidic debris and the overheated metallic RPV wall. It is shown that under the pressurized condition of 10MPa with the sensible heat loss being 50% for the reactors considered in this study, i.e. TMI-2, KORI-2 like, YGN-3&4 like and KNGR like reactors, the heat removal through the gap cooling mechanism was capable of ensuring the RPV integrity as much as 30% to 40% of the total core mass was relocated to the lower plenum. The sensitivity analysis indicated that the cooling rate of debris coupled with the sensible heat loss was a significant factor The newly proposed heat removal capability map (HRCM) clearly displays the critical factors in estimating the maximum heat removal from the debris in the lower plenum. This map can be used as a first-principle engineering tool to assess the RPV thermal integrity during a core melt accident. The predictive model also provided ith a reasonable explanation for the non-failure of the test vessel in the LAVA experiments performed at the Korea Atomic Energy Research Institute (KAERI), which apparently indicated a cooling effect of water ingression through the debris-to-vessel gap and the intra-debris pores and crevices.

• 터널과지하공간
• /
• 제17권5호
• /
• pp.372-380
• /
• 2007

침하로 인한 지표 손상대는 지하 채굴로 인해 발생되는 결과로서, 오랜 기간 동안 서서히 또는 급작스럽게 발생할 수 있다. 이러한 지표 손상대는 싱크홀 혹은 트러프형 침하에서 대규모 슬라딩에 이르기까지 다양한 형태로 관찰된다. 침하 발행 위험에 대한 평가는 광산 침하의 영향을 받는 지역에 있어서는 매우 중요하다. 이러한 위험도 평가나 침하 예측을 위해 경험적 모델, 프로파일함수, 영향 함수 그리고 수치해석과 같은 다양한 방법들이 적용되어 왔다. 본 연구에서는 다양한 인자들 중 지배적으로 침하 현상을 유발할 수 있는 채굴적과 관련한 정보, 즉 채굴적의 위치 및 규모의 정보를 확산이론과 연계한 비교적 간단한 침하 위험도 평가 기법을 제안하였다. 확산 모델은 지반 침하 기구를 설명할 수 있는 입자 모델과 상사관계를 가진다. 확산 모델을 폐금속광 및 폐석탄광 지역의 침하 위험도 작성에 적용하였다. 침하 위험도 평가를 위한 확산 모델은 매우 간단하지만 효율적인 방법임을 확인할 수 있었다.

• 한국지반공학회논문집
• /
• 제20권7호
• /
• pp.45-55
• /
• 2004

경화 모래와 같은 단단한 흙에서는 자주 파괴시의 응력이 실내실험을 통해 얻은 전단강도 보다 작을 뿐만 아니라 일반적인 해석방법이 적절하지 못한 경우를 보게된다. 여러 학자들은 이러한 현상이 일어나는 것은 흙속에 있는 균열이나 절리와 같은 불연속이 존재 하기 때문일거라 생각했고, 따라서 파괴역학이 이런 흙에대해서는 더 적절한 해석방법이 될 수도 있다고 생각 해왔다. 그러나 파괴역학의 개념을 도입하기에는 파괴 요소들이 재료의 구성뿐만 아니라 시료 그리고 입자의 크기에 크게 영향을 받기 때문에 어려움이 많이 있다. 본 연구에서는 경화모래의 파괴 특성에 시료와 입자의 크기가 미치는 영향을 기술한다. 실내실험 결과, 시료와 입자의 크기는 경화모래의 파괴 거동에 많은 영향을 미치는 것을 보여준다.

• Earthquakes and Structures
• /
• 제14권3호
• /
• pp.215-227
• /
• 2018

Supplemental passive control devices are widely considered as an important tool to mitigate the dynamic response of a building under seismic excitation. Nevertheless, a systematic method for strategically placing dampers in the buildings is not prescribed in building codes and guidelines. Many deterministic and stochastic methods have been proposed by previous researchers to investigate the optimum distribution of the viscous dampers in the steel frames. However, the seismic performances of the retrofitted buildings that are under large earthquake intensity levels or near collapse state have not been evaluated by any seismic research. Recent years, an increasing number of studies utilize genetic algorithms (GA) to explore the complex engineering optimization problems. GA interfaced with nonlinear response history (NRH) analysis is considered as one of the most powerful and popular stochastic methods to deal with the nonlinear optimization problem of damper distribution. In this paper, the effectiveness and the efficiency of GA on optimizing damper distribution are first evaluated by strong ground motions associated with the collapse failure. A practical optimization framework using GA and NRH analysis is proposed for optimizing the distribution of the fluid viscous dampers within the moment resisting frames (MRF) regarding the improvements of large drifts under intensive seismic context. Both a 10-storey and a 20-storey building are involved to explore higher mode effect. A far-fault and a near-fault earthquake environment are also considered for the frames under different seismic intensity levels. To evaluate the improvements obtained from the GA optimization regarding the collapse performance of the buildings, Incremental Dynamic Analysis (IDA) is conducted and comparisons are made between the GA damper distribution and stiffness proportional damping distribution on the collapse probability of the retrofitted frames.

• 한국항행학회논문지
• /
• 제22권3호
• /
• pp.179-188
• /
• 2018

항공전자 시스템의 개발할 때 항공 사고를 예방하기 위해서 SAE ARP4761 (민간 항공 시스템 및 장비 안전성 평가 프로세스 수행 방법 및 지침) 규격에 명시된 안전성 분석 및 평가를 수행한다. 안전성 분석은 시스템의 정상상태가 아닌 비정상상태에 대한 지식과 다른 규격들 간의 상호 연관성에 대한 지식이 요구된다. 때문에, 안전인증규격의 준수를 입증하는 자료를 자동으로 출력하는 도구가 필요하다. 본 연구는 규격의 안전성 분석 절차를 도식화하고, 안전 분석 CAD 도구들을 개별 절차에 적용하는 방법을 연구하였다. 예시 연구로서, ARP4761 부록의 여객기용 휠 제동 시스템 (WBS; wheel brake system)을 대상으로 ARP4761분석을 수행하였다.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2000년도 추계학술대회논문집A
• /
• pp.250-255
• /
• 2000

Damage induced by low velocity impact loading in aircraft composite laminates is the form of failure which is occurred frequently in aircraft. Low velocity impact can be caused either by maintenance accidents with tool drops or by in-flight impacts with debris. As the consequences of impact loading in composite laminates, matrix cracking, delamination and eventually fiber breakage for higher impact energies can be occurred. Even when no visible impact damage is observed, damage can exist inside of composite laminates and the carrying load of the composite laminates is considerably reduced. The reduction of strength and stiffness by impact loading occurs in compressive loading due to laminate buckling in the delaminated areas. The objective of this study is to determine inside damage of composite laminates by impact loading and to determine residual compressive strength and the damage growth mechanisms of impacted composite laminates. For this purpose a series of impact and compression after impact tests are carried out on composite laminates made of carbon fiber reinforced epoxy resin matrix with lay up pattern of $[({\pm}45)(0/90)_2]s$ and $[({\pm}45)(0)_3(90)(0)_3({\pm}45)]$. UT-C scan is used to determine impact damage characteristics and CAI(Compression After Impact) tests are carried out to evaluate quantitatively reduction of compressive strength by impact loading.

• 한국산학기술학회논문지
• /
• 제18권12호
• /
• pp.80-87
• /
• 2017

과거 미국은 낙후된 도심 지역을 되살리기 위한 도시재생의 도구로 대규모 도시개발사업을 진행하여왔고, 이를 통해 현재의 공공주도적 사업형태를 개발하였다. 특히 2008년의 경제위기이후 세계적으로 대규모 도시개발사업이 정체되거나 중단되었으나, 본 연구의 분석대상 사업인 미국 뉴욕시의 허드슨 야드 개발은 그 구조적 특성 및 합리적 협상과정을 통해 경제위기로 인한 어려움을 극복하고 현재 순조롭게 진행되고 있다. 그러나 이와 유사하게 경제상황에 좌우되는 국내 대부분의 개발은 민간주도로 이루어지고 있는 개발현실에서 노출되는 문제점을 반복하고 있으며, 그 대표적인 실패 사례가 용산국제 업무지구 개발이다. 이에 본 연구는 과거 용산국제업무지구 개발의 실패에서 노출된 주요 미비점을 중심으로 허드슨 야드 개발에서 나타나는 사업의 구조적 특성 및 협상과정상의 특성을 분석함으로, 위기를 극복할 수 있게 한 개발 사업의 구조적 유연성과 합리적 협상내용으로 부터 국내 참조가능한 시사점을 도출하고자 한다. 이를 통해 국내 대규모 도시개발의 계획시, 본 연구에서 도출된 다양하고 상이한 구조적 특징과 위기대처 방안의 시사점을 통하여 보다 합리적이고 위기상황에 유연한 개발로 계획함에 일조하고자 한다.