• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1494-1498
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• 2004

Transition sequence of rocket to ramjet was simulated numerically for a two-dimensional axisymmetric can-type ramjet engine. Multi-species preconditioned Navier-Stokes equations with $k-{\varepsilon}$ turbulence model and finite-rate chemistry model was employed. To calculate transition sequence, initial flow-field conditions for inlet diffuser with closed port-cover was computed first, and then that result was applied as initial conditions after port-cover opened. Terminal shock was developed as a result of increased pressure in a combustor due to combustion and ramjet operated at supercritical condition. For a smaller nozzle throat area, buzz instability was occurred. Strong pressure oscillations were observed as a result of forward and backward movement of terminal shock and those oscillations were not damped out.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.649-656
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• 2004

Hypersonic wind tunnel test of the rectangular variable geometry intake is performed. For realization of a Precooled turbojet engine, development of a hypersonic ramjet engine is planned. To investigate performance of the intake of the hypersonic ramjet engine, wind tunnel test is done with freestream Mach number of 5.1. The total pressure recovery was 18 % with 12.9 % of ramp bleed. Several reasons for low total pressure recovery are shown. Supersonic internal compression is not enough. Then, the throat Mach number is high (M2.61) and total pressure losses at the terminal shock is large. Supersonic flow at the throat and position of the terminal shock is sensitive to a difference of the second ramp's throat height and the third ramp's throat height. Flow separations at the second ramp's trailing edge and the third ramp's leading edge are seen those could result in the trigger of unstart. The seal mechanism between the ramps and the sidewalls is important.

• Molecules and Cells
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• v.43 no.8
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• pp.694-704
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• 2020

HslUV is a bacterial heat shock protein complex consisting of the AAA+ ATPase component HslU and the protease component HslV. HslV is a threonine (Thr) protease employing the N-terminal Thr residue in the mature protein as the catalytic residue. To date, HslUV from Gram-negative bacteria has been extensively studied. However, the mechanisms of action and activation of HslUV from Gram-positive bacteria, which have an additional N-terminal sequence before the catalytic Thr residue, remain to be revealed. In this study, we determined the crystal structures of HslV from the Gram-positive bacterium Staphylococcus aureus with and without HslU in the crystallization conditions. The structural comparison suggested that a structural transition to the symmetric form of HslV was triggered by ATP-bound HslU. More importantly, the additional N-terminal sequence was cleaved in the presence of HslU and ATP, exposing the Thr9 residue at the N-terminus and activating the ATP-dependent protease activity. Further biochemical studies demonstrated that the exposed N-terminal Thr residue is critical for catalysis with binding to the symmetric HslU hexamer. Since eukaryotic proteasomes have a similar additional N-terminal sequence, our results will improve our understanding of the common molecular mechanisms for the activation of proteasomes.

• Biomedical Science Letters
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• v.9 no.2
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• pp.105-110
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• 2003

Ankyrins are a ubiquitously expressed family of intracellular adaptor proteins involved in targeting diverse proteins to specialized membrane domains in both the plasma membrane and the endoplasmic reticulum. Canonical ankyrins are 190-220 kDa proteins expressed in most tissues and cell types and comprise a membrane-binding domain (MBD) of 24 ANK repeats, a spectrin-binding domain, a death domain and a C-terminal domain. Rescue studies with ankyrin-B/G chimeras have identified the C-terminal domain of ankyrin-B as the defining domain in specifying ankyrin-B activity, but the function of C-terminal domain of ankyrin-B is, however, not known. We report here that the C-terminal domain of ankyrin-B is capable of interacting with the C-terminal Region of Hsp40. The Hsps are induced not only by heat shock but also by various other environmental stresses. Hsps are also expressed constitutively at normal growth temperatures and have basic and indispensable functions in the life cycle of proteins as molecular chaperones, as well as playing a role in protecting cells from the deleterious stresses. The binding sites required in the interaction between C-terminal domain of ankyrin-B and C-terminal region of Hsp40 were characterized using the yeast two-hybrid system and GST-pull down assay. The interaction between ankyrin-B and Hsp40 represents the first direct evidence of ankyrin's role as chaperones.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1996.11a
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• pp.107-116
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• 1996

Numerical simulations have been conducted to characterize unsteady flow structures in an axisymmetric supersonic inlet diffuser with sinusoidal pressure oscillations at the diffuser exit. The formulation is based on the unsteady Navier-Stokes equations and turbulence closure is achieved using a two-layer model with a too-Reynolds-number scheme for the near-wall treatment. The governing equations are formulated in an integral form, and are discretized by the four-stage Runge-Kutta scheme for temporal terms and the Harten-Yee upwind TVD scheme for convective terms. Results indicated that the inlet shock characteristics are significantly modified by acoustic oscillations originating from the combustor. The characteristics of shock/boundarv-layer interactions (such as the size of separation bubble, terminal shock shape, and vorticity intensity) are also greatly iufluenced by the shock oscillation due to acoustic waves.

• Journal of Life Science
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• v.28 no.6
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• pp.639-647
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• 2018

A new heat shock protein 70 was identified in red-spotted grouper (Epinephelus akaara) based on an expression analysis. The cDNA of red-spotted grouper Hsp70 (designated RgHsp70) was cloned by the rapid amplification of cDNA ends (RACE) techniques. The full-length of RgHsp70 cDNA was 2,152 bp, consisting of a 5'-terminal untranslated region (UTR) of 105 bp, a 3'-terminal UTR of 274 bp, and an open reading frame (ORF) of 1,773 bp that encode a polypeptide of 590 amino acids with a theoretical molecular weight of 64.9 kDa and an estimated isoelectric point of 5.2. Multiple alignment and phylogenetic analyses revealed that the RgHsp70 gene shares a high similarity with other Hsp70 fish genes. RgHsp70 contained all three classical Hsp70 family signatures. The results indicated the RgHsp70 is a member of the heat shock protein 70 family. RgHsp70 mRNA was predominately expressed in the liver, with reduced expression noted in the head-kidney tissues. The expression analysis of different water temperatures (21, 18, 15 and $12^{\circ}C$) for sampled livers revealed that expression gradually increased at $12^{\circ}C$ compared to $21^{\circ}C$. In this study, the effects of water temperature lowering on the physiological conditions were investigated, and the results revealed that novel RgHsp70 may be an important molecule involved in stress responses.

• Korean Journal of Microbiology
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• v.38 no.2
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• pp.67-73
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• 2002

The cellular responses of soil-borne bacterium, Pseudomonas sp. HK-6 to explosive 2,4,6-trinitrotoluene (TNT) were examined. Two stress shock proteins (SSPs), approximately 70-kDa DnaK and a 60-kDa GroEL were found in HK-6 cells in response to TNT. Analyses of SDS-PAGE and Western blot using anti-DnaK and GroEL revealed that SSPs were induced in HK-6 cells exposed to 0.5 M of TNT far 6-12 hrs. The maximum induction of proteins was achieved at 8-hr incubation point after HK-6 cells'exposure to TNT. Similar SSPs were found to be induced in HK-6 cells by heat shock (shift of temperature, from $30^{\circ}C$ to $42^{\circ}C$) or cold shock (shift of temperature,$30^{\circ}C$ to $4^{\circ}C$).2D-PAGE of soluble protein tractions from the culture of Pseudomonas sp. HX-6 exposed to TNT demonstrated that approximately 450 spots were observed on the silver stained gels ranging from pH 3 to pH 10. Among them, 12 spots significantly induced and expressed in response to TNT were selected and analyzed. Approximately 60-kDa protein, which was assumed highly expressed on the gel, was used for amino acid sequencing. N-terminal microsequencing with in-gel digestion showed that N-terminal sequence of the TNT-induced protein, <$^1XXAKDVKFGDSARKKML^17$, shared extensive similarity with $^1XXAKDVKFGDSARKKML^17$, N-terminal sequence of (P48216) GroEL of Pseudomonas putida.

• Journal of Korean Academy of Nursing
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• v.42 no.2
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• pp.280-290
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• 2012

Purpose: This study done to identify the experiences of families caring for patients with terminal cancer. The question was, "What is the caregiving experience of a family who has a member with terminal cancer?" Methods: Grounded Theory was applied and in-depth interviews were done with 11 family members. Interviews were recorded with the interviewees' consent and were transcribed and analyzed. Participants' relationships to patients were 6 spouses, 4 daughters, and 1 mother. The ages of the participants were between 32 and 62, with an average of 47.5. Results: The study showed "enduring with bonds" as the main category and the main factor affecting this category was the "patients' diagnosis of terminal cancer." The caregiving experience was divided into four stages: shock, confusion, struggle, and acceptance. Mediating factors were relationship with the patient, intimacy with the patient, social support, communication, and trust. Conclusively, participants underwent internal maturity, and changes occurred in family and social and personal life. Conclusion: The families took care of the patients with responsibility and love. The study results should help with the understanding of a family with a member with terminal cancer and should be used to develop nursing, mediating, and consulting programs for these caregivers.

• Journal of Trauma and Injury
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• v.27 no.4
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• pp.204-207
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• 2014

Non-occlusive mesenteric ischemia (NOMI) encompasses all forms of mesenteric ischemia with patent mesenteric arteries. NOMI is commonly caused by decreased cardiac output resulting in hypoperfusion of peripheral mesenteric arteries. We report a case of NOMI secondary to hemorrhagic shock and rhabdomyolysis due to trauma. A 42-year-old man presented to our trauma center following a pedestrian trauma. On arrival, he was drowsy and in a state of hemorrhagic shock. He was found to have multiple fractures, both lung contusion and urethral rupture. An initial physical examination and abdominal computed tomography (CT) scan revealed no evidence of intra-abdominal injury. High doses of catecholamine were administered for initial 3 days due to unstable vital sign. On day 25 of hospitalization, follow-up abdominal CT scan demonstrated that short segment of small bowel loop was dilated and bowel wall was not enhanced. During exploratory laparotomy, necrosis of the terminal ileum with intact mesentery was detected and ileocecectomy was performed. His postoperative course was uneventful and is under rehabilitation.

• BMB Reports
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• v.38 no.5
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• pp.602-608
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• 2005

As a crucial transcription factor family, heat-shock factors were mainly analyzed and characterized in tomato and Arabidopsis. In this study, we isolated two putative heat shock factors OsHSF6 and OsHSF12 that interact specifically with heat-shock element (HSE) from Oryza sativa L by yeast one-hybrid method. The full-length cDNA of OsHSF6 and OsHSF12 have 1074bp and 920bp open reading frame (ORF), respectively. Analysis of the deduced amino acid sequences revealed that OsHSF6 was a class A heat shock factor (HSF) with all the conserved sequence elements characteristic of heat stress transcription factor, while OsHSF12 was a class B HSF with C-terminal domain (CTD) lacking of AHA motif. Bioinformatic analysis showed that the sequences and structures of two HSFs' DNA binding domain (DBD) had a high similarity with LpHSF24. The results of RT-PCR indicated OsHSF6 gene was expressed immediately after rice plants exposure to heat stress, and the transcription of OsHSF6 gene accumulated primarily in immature seeds, roots and leaves. However, we did not find the transcription of OsHSF12 gene in different organs and growth periods. Our results implied that OsHSF6 might be function as a HSF regulating early expression of stress genes in response to heat shock, and OsHSF12 might be act as a synergistic factor to regulate the expression of down-stream genes.