• Structural Engineering and Mechanics
• /
• 제77권3호
• /
• pp.305-314
• /
• 2021

In order to reduce enormous cost of real-scale underwater explosion experiments on ships, the mechanical response of the ships have been analyzed by combining scaled-down experiments and Hopkinson's scaling law. However, the Hopkinson's scaling law is applicable only if all variables vary in an identical ratio; for example, thickness of ship, size of explosive, and distance between the explosive and the ship should vary with same ratio. Unfortunately, it is infeasible to meet such uniform scaling requirement because of environmental conditions and limitations in manufacturing scaled model systems. For the facile application of the scaling analysis, we propose a generalized scaling law that is applicable for non-uniform scaling cases in which different parts of the experiments are scaled in different ratios compared to the real-scale experiments. In order to establish such a generalized scaling law, we conducted a parametric study based on numerical simulations, and validated it with experiments and simulations. This study confirms that the initial peak value of response variables in a real-scale experiment can be predicted even when we perform a scaled experiment composed of different scaling ratios for each experimental variable.

• Pediatric Gastroenterology, Hepatology & Nutrition
• /
• 제4권2호
• /
• pp.175-180
• /
• 2001

목적: 공기 정복술은 조작이 간단하고 정복 시간이 빠르며 방사선 노출 시간이 짧고 천공 이환률이 낮다는 장점이 있다. 장중첩증 치료에 정복술에 실패한 경우 수술적 치료를 하게 되는데 대부분은 장절제 없이 단순 도수 정복만으로 치료되는 경우가 많으며 상당수에서는 이미 정복된 상태로 발견되기도 한다. 일차 공기 정복술에 실패한 장중첩증 환자에서 반복 지연 정복술을 시행하여 그 유용성 및 안전성을 알아보고자 본 연구를 시행하였다. 방법: 1998년 1월부터 1999년 12월까지 일차 공기 정복술을 시행하여 실패한 환자 중 복막염, 쇼크, 독성 증상이 없는 임상적으로 안정된 21명을 대상으로 1시간에서 3시간(평균 2.2 시간)후에 이차 지연 정복을 시행하였다. 결과: 정복술 시행 전 환자들의 증상 및 징후의 지속 시간은 6~48시간이었으며 평균 24시간이었다. 일차 정복 후 1~3시간 후(평균 2.2 시간)에 이차 지연 정복술을 시행하였고 76.2% (21례 중 16례)에서 성공적으로 정복되었으며 나머지 5례는 수술적 치료를 하였다. 이중 4례는 도수 정복되었으며 1례는 자연 정복되어 있었다. 결론: 초기 정복에 실패한 장중첩증 환자에서 임상적으로 안정적일 경우 시간 간격을 두고 반복지연 정복술을 시행하는 것은 불필요한 수술의 빈도를 줄일 수 있을 것으로 사료된다.

• 대한의생명과학회지
• /
• 제12권2호
• /
• pp.81-89
• /
• 2006

The ischemia-responsive 94 gene (irp94) encoding a 94 kDa endoplasmic reticulum resident protein was investigated its molecular properties associated with unfoled protein responses. First, the expression of irp94 mRNA was tested after the reperfusion of the transient forebrain ischemia induction at the central nervous system in three Mongolian gerbils. Second, irp94 expression in PC12 cells, which are derived from transplantable rat pheochromocytoma cultured in the DMEM media, was tested at transcriptional and translational levels. The half life of irp94 mRNA was also determined In PC12 cells. Last, the changes of irp94 mRNA expression were investigated by the addition of various ER stress inducible chemicals (A23187, BFA, tunicamycin, DTT and $H_2O_2$) and proteasome inhibitors, and heat shock. High level expression of irp94 mRNA was detected after 3 hours reperfusion in the both sites of the cerebral cortex and hippocampus of the gerbil brain. The main regulation of irp94 mRNA expression in PC 12 cells was determined at the transcriptional level. The half life of irp94 mRNA in PC12 cells was approximately 5 hours after the initial translation. The remarkable expression of irp94 mRNA was detected by the treatment of tunicamycin, which blocks glycosylation of newly synthesized polypeptides, and $H_2O_2$, which induces apoptosis. When PC12 cells were treated with the cytosol proteasome inhibitors such as ALLN (N-acetyl-leucyl-norleucinal) and MG 132 (methylguanidine), irp94 mRNA expression was increased. These results indicate that expression of irp94 was induced by ER stress including oxidation condition and glycosylation blocking in proteins. Expression of irp94 was increased when the cells were chased after heat shock, suggesting that irp94 may be involved in recovery rather than protection against ER stresses. In addition, irp94 expression was remarkably increased when cytosol proteasomes were inhibited by ALLN and MG 132, suggesting that irp94 plays an important role for maintaining the ERAD (endoplasmic reticulum associated degradation) function.

• 천문학회지
• /
• 제36권3호
• /
• pp.89-95
• /
• 2003

Observations of dark matter dominated dwarf and low surface brightness disk galaxies favor density profiles with a flat-density core, while cold dark matter (CDM) N-body simulations form halos with central cusps, instead. This apparent discrepancy has motivated a re-examination of the microscopic nature of the dark matter in order to explain the observed halo profiles, including the suggestion that CDM has a non-gravitational self-interaction. We study the formation and evolution of self-interacting dark matter (SIDM) halos. We find analytical, fully cosmological similarity solutions for their dynamics, which take proper account of the collisional interaction of SIDM particles, based on a fluid approximation derived from the Boltzmann equation. The SIDM particles scatter each other elastically, which results in an effective thermal conductivity that heats the halo core and flattens its density profile. These similarity solutions are relevant to galactic and cluster halo formation in the CDM model. We assume that the local density maximum which serves as the progenitor of the halo has an initial mass profile ${\delta}M / M {\propto} M^{-{\epsilon}$, as in the familiar secondary infall model. If $\epsilon$ = 1/6, SIDM halos will evolve self-similarly, with a cold, supersonic infall which is terminated by a strong accretion shock. Different solutions arise for different values of the dimensionless collisionality parameter, $Q {\equiv}{\sigma}p_br_s$, where $\sigma$ is the SIDM particle scattering cross section per unit mass, $p_b$ is the cosmic mean density, and $r_s$ is the shock radius. For all these solutions, a flat-density, isothermal core is present which grows in size as a fixed fraction of $r_s$. We find two different regimes for these solutions: 1) for $Q < Q_{th}({\simeq} 7.35{\times} 10^{-4}$), the core density decreases and core size increases as Q increases; 2) for $Q > Q_{th}$, the core density increases and core size decreases as Q increases. Our similarity solutions are in good agreement with previous results of N-body simulation of SIDM halos, which correspond to the low-Q regime, for which SIDM halo profiles match the observed galactic rotation curves if $Q {\~} [8.4 {\times}10^{-4} - 4.9 {\times} 10^{-2}]Q_{th}$, or ${\sigma}{\~} [0.56 - 5.6] cm^2g{-1}$. These similarity solutions also show that, as $Q {\to}{\infty}$, the central density acquires a singular profile, in agreement with some earlier simulation results which approximated the effects of SIDM collisionality by considering an ordinary fluid without conductivity, i.e. the limit of mean free path ${\lambda}_{mfp}{\to} 0$. The intermediate regime where $Q {\~} [18.6 - 231]Q_{th}$ or ${\sigma}{\~} [1.2{\times}10^4 - 2.7{\times}10^4] cm^2g{-1}$, for which we find flat-density cores comparable to those of the low-Q solutions preferred to make SIDM halos match halo observations, has not previously been identified. Further study of this regime is warranted.

• Tuberculosis and Respiratory Diseases
• /
• 제69권6호
• /
• pp.469-473
• /
• 2010

Nocardia farcinia, an aerobic, gram-positive bacilli actinomycetes of the genus Nocardia, is an uncommon pathogen found in humans. The most common Nocardia infection sites are the lung, central nervous system, and skin. Even though hematogenous dissemination can occur, isolation of the organism from blood cultures is very rare. We report a case of Nocardia infection that was isolated on blood cultures. A 59-year-old male with a medical history that includes a liver transplantation 6-years prior due to hepatocellular carcinoma secondary to chronic hepatitis B, developed pneumonia and was transferred to Severance Hospital. At the time of admission, the patient's initial exam showed hypothermia, tachypnea, and hypotension. His chest radiograph showed severe pneumonia and a large abscess on left upper lobe. Under the presumptive diagnosis of bacterial pneumonia or other opportunistic infection, we started broad spectrum antibiotics. However, he developed Nocardia sepsis, rapidly deteriorated, and subsequently died.

• Journal of Animal Science and Technology
• /
• 제64권6호
• /
• pp.1046-1062
• /
• 2022

This study investigated the effects of L-glutamine (Gln) supplementation on growth performance, physiological traits, heat shock proteins (HSPs), and gene expression related to muscle and adipose tissue development in Hanwoo steers under heat stress (HS) conditions. Eight Hanwoo steers (initial body weight [BW] 570.7 ± 43.6 kg, months of age 22.3 ± 0.88) were randomly separated into two groups, control and treatment, and supplied with the concentration (1.5% of BW kg/day/head) and rice straw (1.5 kg/day/head). The treatment group were fed the Gln supplementation (0.5% of concentration, as-fed basis) once a day at 08:00 h. Blood samples for the assessment of haematological and biochemical parameters and the separation of peripheral blood mononuclear cells (PBMCs) were collected four times, at 0, 3, 6, and 10 weeks of the experiment. Feed intake was measured daily. BW to analyze growth performance and hair follicle collection to analyze the expression of HSPs were executed four times at 0, 3, 6, and 10 weeks. To analyze gene expression, longissimus dorsi muscle samples were collected by biopsy at the end of the study. As a result, growing performance, including final BW, average daily gain, and gain-to-feed ratio, were not different between the two groups. Leukocytes including lymphocytes and granulocytes, tended to increase in the Gln supplementation group (p = 0.058). There were also no differences in biochemical parameters shown between the two groups, except total protein and albumin, both of which were lower in the Gln supplementation group (p < 0.05). Gene expressions related to muscle and adipose tissue development were not different between the two groups. As temperature-humidity index (THI) increased, HSP70 and HSP90 expression in the hair follicle showed a high correlation. HSP90 in the hair follicle was decreased in the treatment group compared with the control group at 10 weeks (p < 0.05). Collectively, dietary Gln supplementation (0.5% of concentration, as-fed basis) may not be influential enough to affect growth performance and gene expression related to muscle and adipose tissue development in steers. However, Gln supplementation increased the number of immune cells and decreased HSP90 in the hair follicle implying HS reduction in the corresponding group.

• Journal of Chest Surgery
• /
• 제43권6호
• /
• pp.669-674
• /
• 2010

배경: 자연성 혈기흉은 외상이나 다른 뚜렷한 원인 없이 흉강 내 공기와 400 mL 이상의 혈액이 동시에 쌓이는 질환이다. 드문 질환이지만 생명을 위협할 수도 있는 질환이기도 하다. 이 질환의 적절한 치료를 알아보고자 두 병원에서 치료받은 환자들을 분석하였다. 대상 및 방법: 2003년 3월부터 2010년 8월까지 치료받은 18명의 자연성 혈기흉 환자들을 후향적으로 조사하였다. 결과: 18명의 환자들 중 남자 15명 여자 3명이었고 평균 나이는 24.6세이었다. 16명의 환자는 우선적으로 폐쇄식 흉관 삽입술을 시행하였으며 15명의 환자는 흉강경을 통한 수술적 치료를 하였다. 수술 후 흉관 제거는 평균 2.9일에 이루어졌으며, 수술 후 합병증으로 흉관 제거 후 기흉이 한 명 있었다. 퇴원 후 다른 합병증이나 재발은 추적기간 동안 없었다. 결론: 초기의 적절한 진단과 치료가 치명적인 쇼크 상태를 방지하며, 흉강경을 통한 조기 수술이 자연성 혈기흉의 치료가 될 것이다. 그러나 보전적 치료도 일부 환자에게는 효과적이다.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2005년도 제24회 춘계학술대회논문집
• /
• pp.281-287
• /
• 2005

연소불안정에서 흔히 수반되는 충격파와 한계사이클 같은 비선형적 거동을 수치해석을 통해 고찰하였다. 공진관에 가해진 초기 압력교란이 충격파로 천이되는 과정을 해석함으로서 비선형 음향특성에 대한 이해를 돕는 동시에 수치해석기법의 정확성을 검증하였다. ${\eta}-{\tau}$ 연소응답모델을 이용한 SSME의 해석결과는 선형불안정 영역에서 한계사이클의 특성은 연소파라미터와 작동조건에 의존할 뿐 초기 교란의 특성과는 무관함을 밝혔다. 또한 1.5 MW급 가스발생기의 개발 과정에서 겪은 연소불안정 문제에 적용하여 예측된 안정성 경향을 연소시험 결과와 비교함으로서, 향후 수치해석을 통한 연소불안정 예측기법에 대해 가능성을 확인하는 동시에 향후 연구방향을 모색하였다.

• 터널과지하공간
• /
• 제22권3호
• /
• pp.221-225
• /
• 2012

마그네슘 합금은 경량화 재료로서 많은 주목을 받고 있으나, 스테인레스 스틸과의 접합이 어려운 문제점이 있다. 본 연구에서는 수중충격파를 이용하여 스테인레스 스틸(SUS304)과 마그네슘 합금(AZ31)의 폭발용접을 수행하고 접합특성에 관한 분석을 수행하였다. SUS304의 두께는 0.5 mm와 1 mm를 사용하였으며, 폭약과 재료의 이격거리는 45 mm, 폭약의 설치경사는 $20^{\circ}$로 하여 실험한 결과, 두 재료의 접합면에서 중간층(resolidified interlayer)이 형성되었다. 중간층의 형성을 억제하기 위하여 폭약과 재료의 거리를 60 mm로 증가시켰으며 폭약의 경사는 $30^{\circ}$으로 변경하여 폭발용접실험을 수행하였다. 그 결과, 폭약과 재료 사이의 간격과 경사각이 증가함에 따라 중간층이 나타나지 않는 경향을 보였다. 이 중간층에 대하여 EPMA분석한 결과, 중간층은 두 금속의 재료가 혼합되어 있는 것으로 확인 되었으며, 경도는 두 금속의 평균 경도에 해당 됨이 확인 되었다.

• 한국어류학회지
• /
• 제6권1호
• /
• pp.71-78
• /
• 1994

참돔 암 수 친어에 5 mg/kg 체중의 잉어 뇌하수체 추출물(CPE) 및 1,000 IU/kg 체중의 태반성 성선자극 호르몬(HCG)을 주사, 인공 산란을 유도한 후 수정난에 $3^{\circ}C$의 저온 처리를 가하여 참돔 3배체를 유도하였다. 그 결과 수정 후 6분에 $3^{\circ}C$의 저온으로 20분 및 30분간 처리시 100%의 3배체 유도율을 나타내었으며 초기 생존율을 고려시 81.3% 및 80.0%의 높은 3배체 생산율을 각각 나타내었다. 유도 3배체는 2배체에 비해 염색체수와 적혈구 세포 및 핵의 크기에 있어 증가를 보여 3배체는 2배체에 비해 세포핵의 부피가 1.58배 증가하였다. 염색체 및 핵형은 대조군이 2n=48 acrocentric 염색체인 반면, 3배체는 72개의 acrocentric 염색체로 구성되어 있었다. 부화 10일 후부터 34일 까지의 유도 3배체의 초기 전장 성장 및 부레 성장은 2배체의 그것에 비해 낮게 나타났다.