• 설비공학논문집
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• 제12권9호
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• pp.825-834
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• 2000

A heat exchanger analysis is performed to investigate the heating characteristics of cryogenic nitrogen by ambient air for the purpose of cryogenic automotive propulsion. The heat exchanger is a concentric triple-passage for supercritical nitrogen, and the radial fins are attached on the outermost tube for the crossflow of ambient air. The temperature distribution is calculated for the nitrogen along the passage, including the real gas properties of nitrogen, the fluid convections and the conductions through the tube walls and the fins. Since the wall temperature of the outer (ambient side) tube is very low in most cases, a heavy frost can be formed on the surface, affecting the heat exchange performance. By the method of the similarity between the heat and the mass transfer of moist air, the frost growth and the time-dependent effectiveness of the heat exchanger are calculated for various operating conditions. It is concluded that the frost formation can augment the heating of nitrogen during the initial period because of the latent heat, then gradually degrades the heat exchange because of the increased thermal resistance. Practical design issues are discussed for the flow rate of nitrogen, the velocity and humidity of ambient air, and the sizes of the fin.

• KSBB Journal
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• 제26권3호
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• pp.211-216
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• 2011

To study the effects of ethanol extract of the Rhodiola Sachalinensis on the anti-oxidation and blood pressure and skeletal muscles contractility in rats. The ethanol extracts and fractions of Rhodiola Sachalinensis were determinated the anti-oxidation effects by DPPH(1,1-dipenyl-2-picrylhydrazyl) method and comparing with the BHA (Butylated hydroxyanisole) and AA(Ascorbic acid). The gastrocnemius and soleus muscle contractility were observed by stimulating the sciatic nerve with electricity after affusing stomach with ethanol extract of the 200 mg/kg dosage of Rhodiola Sachalinensis for 4 weeks. The ethanol extract of the Rhodiola Sachalinensis could shorten latent period, increase maximal contractive extent and time and relaxative time at the twitch and complete tetanus of gastrocnemius and soleus muscles. The ethanol extract of the Rhodiola Sachalinensis shows high anti-oxidation effect and can enhance skeletal muscles contractility in rats.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1122-1127
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• 2004

an isolated droplet combustion exposed to pressure perturbations in stagnant gaseous environment is numerically conducted. Governing equations are solved for flow parameters at gas and liquid phases separately and thermodynamic parameters at the interfacial boundary are matched for problem closure. For high-pressure effects, vapor-liquid interfacial thermodynamics is rigorously treated. A series of parametric calculations in terms of mean pressure level and wave frequencies are carried out employing a n-pentane droplet in stagnant gaseous air. Results show that the operating pressure and driving frequency have an important role in determining the amplitude and phase lag of a combustion response. Mass evaporation rate responding to pressure waves is amplified with increase in pressure due to substantial reduction in latent heat of vaporization. Phase difference between pressure and evaporation rate decreases due to the reduced thermal inertia at high pressure. In addition to this, augmentation of perturbation frequency also enhances amplification of vaporization rate because the time period for the pressure oscillation is much smaller than the liquid thermal inertia time. The phase of evaporation rate shifts backward due to the elevated thermal inertia at high acoustic frequency.

• Asian Journal of Atmospheric Environment
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• 제10권1호
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• pp.42-50
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• 2016

This study presents a performance evaluation of four different land surface models (LSM) available in Weather Forecast Research (WRF). The research site was located in Haean Basin in South Korea. The basin is very unique by its geomorphology and topography. For a better representation of the complex terrain in the mesoscale model were used a high resolution topography data with a spatial resolution of 30 meters. Additionally, land-use layer was corrected by ground mapping data-sets. The observation equipments used in the study were an ultrasonic anemometer with a gas analyzer, an automatic weather station and a tethered balloon sonde. The model simulation covers a four-day period during autumn. The result shows significant impact of LSM on meteorological simulation. The best agreement between observation and simulation was found in the case of WRF with Noah LSM (WRF-Noah). The WRF with Rapid Update Cycle LSM (WRF-RUC) has a very good agreement with temperature profiles due to successfully predicted fog which appeared during measurements and affected the radiation budget at the basin floor. The WRF with Pleim and Xiu LSM (WRF-PX) and WRF with Thermal Diffusion LSM (WRF-TD) performed insufficiently for simulation of heat fluxes. Both overestimated the sensible and underestimated the latent heat fluxes during the daytime.

• Journal of Korean Neurosurgical Society
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• 제50권6호
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• pp.535-537
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• 2011

Recently, combination of surgery and radiation therapy (RT) has been recommended in the treatment of craniopharyngioma. RT could be associated with late complications, including vasculopathy. We report two cases of the moyamoya syndrome seen in children with craniopharyngioma who received RT after surgical resection. Thirty-five patients in pediatric age with craniopharyngioma were surgically treated. Fifteen out of 35 patients underwent surgical resection followed by RT or gamma knife surgery. Two of the 15 were found to have symptoms of transient ischemic attack and were diagnosed as moyamoya syndrome through the cerebral angiography. Age at RT was 4 and 13 years, respectively. The latent period for development of the moyamoya syndrome was 27 months and 3 years, respectively, after RT. The RT dose of both patients was 54 Gy. These two patients received bilateral encephaloduroarteriosynangiosis procedures. We report here these two cases of radiation-induced moyamoya syndrome in pediatric craniopharyngioma. Pediatric patients with craniopharyngioma who received RT should be reminded, during follow-up, about the risk of development of the moyamoya syndrome.

• Journal of Microbiology and Biotechnology
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• 제26권9호
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• pp.1629-1635
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• 2016

A novel bacteriophage, PBES 02, infecting Cronobacter sakazakii was isolated and characterized. It has a spherical head of 90 nm in diameter and a tail of 130 nm in length, and belongs to Myoviridae as observed under a transmission electron microscope. The major virion protein appears to be 38 kilodaltons (kDa) in size. The latent period of PBES 02 is 30 min and the burst size is 250. Infectivity of the phage remained intact after exposure to temperatures ranging from 4℃ to 55℃ for 1 h. It was also stable after exposure to pHs ranging from 6 to 10 for 1 h. The phage effectively removed contaminating Cronobacter sakazakii from broth infant formula. PBES 02 has a double-stranded DNA genome of 149,732 bases. Its GC ratio is 50.7%. Sequence analysis revealed that PBES 02 has 299 open reading frames (ORFs) and 14 tRNA genes. Thirty-nine ORFs were annotated, including 24 related to replication and regulation functions, 10 related to structural proteins, and 5 related to DNA packaging. The genome of PBES 02 is closely related to that of two other C. sakazakii phages, CR3 and CR8. Comparison of DNA sequences of genes encoding the major capsid protein revealed a wide geographical distribution of related phages over Asia, Europe, and America.

• Journal of Microbiology and Biotechnology
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• 제28권11호
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• pp.1946-1954
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• 2018

The aim of this study was to isolate and characterize a lytic Yersinia enterocolitica-specific phage (KFS-YE) as a biocontrol agent. KFS-YE was isolated and purified with the final concentration of ($11.72{\pm}0.03$) log PFU/ml from poultry. As observed by transmission electron microscopy, KFS-YE consisted of an icosahedral head and a contractile tail, and was classified in the Myoviridae family. KFS-YE showed excellent narrow specificity against Y. enterocolitica only. Its lytic activity was stable at wide ranges of pH (4-11) and temperature ($4-50^{\circ}C$). The latent period and burst size of KFS-YE were determined to be 45 min and 38 PFU/cell, respectively. KFS-YE showed relatively robust storage stability at -20, 4, and $22^{\circ}C$ for 40 weeks. KFS-YE demonstrated a bactericidal effect in vitro against Y. enterocolitica and provided excellent efficiency with a multiplicity of infection as low as 0.01. This study demonstrated the excellent specificity, stability, and efficacy of KFS-YE as a novel biocontrol agent. KFS-YE may be employed as a practical and promising biocontrol agent against Y. enterocolitica in food.

• 태양에너지
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• 제19권2호
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• pp.57-65
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• 1999

[ $H_2O$ ]-NaCl혼합물을 냉축열재로 선택하였으며, 이 혼합물의 상변화온도를 몰농도 변화에 의하여 조절하였다. 그리고 고농도와 저농도의 NaCl과 $H_2O$가 ion-dipole interaction으로 결합하는 구조를 그림으로 가시화하고 가열, 냉각과정에서 $H_2O$-NaCl이 동결, 융해하는 현상을 도시하므로서 융해와 동결과정에서 상변화온도가 2단계로 나타나는 구조적 원인을 구명하였으며, NaCl의 농도변화에 따른 상변화온도를 이론적으로 분석하므로서 실험 및 이론분석 결과의 타당성을 증명할 수 있도록 하였다.

• 대한기관식도과학회지
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• 제12권2호
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• pp.35-41
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• 2006

Traumatic pseudoaneurysm of the intracavernous internal carotid artery(ICA) is extremely rare, but it is life threatening condition because of massive recurrent epistaxis. Unfortunately, the prompt diagnosis and treatment of this disease are frequently delayed due to its rarity and variable latent period, so this disease is regarded as a challenge to clinicians. Optimal therapy for this diseases demands rapid suspicion for it and is essential in order to give the best functional outcome with minimizing its morbidity and mortality. The authors present a case of male patient with traumatic pseudoaneurysm of intracavernous ICA accompanying severe epistaxis. This patient was a 37-year-old male with unilateral blindness and recurrent massive epistaxis after suffering trauma to head. Computed tomography, MRI and carotid artery angiogram showed pseudoaneurysm of intracavernous ICA with sphenoid bone fracture. The patient was effectively managed with occlusion of the pseudoaneurysmal circulation by endovascular interventional embolization technique utilizing mechanically detachable tungsten coils.

• 한국응용곤충학회지
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• 제16권2호
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• pp.87-92
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• 1977

1963년부터 중부지방에 큰 피해를 주고 있는 맥류의 바이러스병을 동정하기 위하여 전자현미경에 의한 바이러스입자 관찰과 매개충을 이용한 전염시험 및 기주범위조사를 한 결과 정상입자의 평균 크기는 길이가 300-370nm였고 폭이 57-60nm였다. 매개충은 애멸구 Laodelphax striatellus(Fallen)로서 충체내 잠복기간은 7-19일이였고 대부분 10일간이었다. Host range는 보리, 옥수수, 밀, Rye맥, 구리 등으로 옥수수외의 기주식물들은 포장에서도 발병이 되고 있다. 그러므로 중부지방에서 발생되고 있는 맥류 바이러스병은 대부분이 북지모자익바이러스병으로 매년 $10\%$내외의 감염율을 보여주고 있으며 춘파맥에서는$100\%$ 감염 될 때도 있다.