• 한국지구과학회지
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• 제30권5호
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• pp.630-645
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• 2009

The tropopause fold event that took place on January 1, 1997 over mid-region on the Korean Peninsula is examined by means of a numerical simulation based on a Mesoscale Model (MM5). The purpose of this paper is to investigate the effects of moisture in reinforcing a tropopause fold linked to an explosive cyclone. Two types of simulations were carried out; 1) simulations for moist conditions in which full physical and dynamic processes are considered and 2) simulations for dry conditions in which cumulus parameterization and cloud microphysics process are excluded. The results of the moist condition simulations demonstrate that the intensity of the central pressure of the cyclone was overestimated compared with the observed values and that the location of the center and the pressure deepening rates (-17 hPa/12 hr) complied with the observed values. The potential vorticity (PV) anomaly on the isentropic surface at 305 K continued to move in a southeast direction on January 1, 1997 and thus created a single tube of tropopause fold covering the northern and the middle area of the Korean Peninsula and reaching the ground surface at 0300 UTC and 0600 UTC. The results of the dry condition simulations show that the tropopause descended to 500 and 670 hPa in 0300 and 0600 UTC, respectively at the same location for the moist condition simulation; however, there was no deep tropopause fold observed. A comparison of the simulated data between the moist and the dry conditions suggests that a deep tropopause fold should happen when there is sufficient moist in the atmosphere and significantly large PV in the lower atmosphere pulls down the upper atmosphere rather than when the tropopause descends itself due to dynamic causes. Thus, it is estimated that moisture in the atmosphere should have played a crucial role in a deep tropopause fold process.

• International Journal of Fluid Machinery and Systems
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• 제2권4호
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• pp.269-277
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• 2009

The current paper focuses on the analysis of transient cavitating flow in pressurised polyethylene pipes, which are characterized by viscoelastic rheological behaviour. A hydraulic transient solver that describes fluid transients in plastic pipes has been developed. This solver incorporates the description of dynamic effects related to the energy dissipation (unsteady friction), the rheological mechanical behaviour of the viscoelastic pipe and the cavitating pipe flow. The Discrete Vapour Cavity Model (DVCM) and the Discrete Gas Cavity Model (DGCM) have been used to describe transient cavitating flow. Such models assume that discrete air cavities are formed in fixed sections of the pipeline and consider a constant wave speed in pipe reaches between these cavities. The cavity dimension (and pressure) is allowed to grow and collapse according to the mass conservation principle. An extensive experimental programme has been carried out in an experimental set-up composed of high-density polyethylene (HDPE) pipes, assembled at Instituto Superior T$\acute{e}$cnico of Lisbon, Portugal. The experimental facility is composed of a single pipeline with a total length of 203 m and inner diameter of 44 mm. The creep function of HDPE pipes was determined by using an inverse model based on transient pressure data collected during experimental runs without cavitating flow. Transient tests were carried out by the fast closure of the ball valves located at downstream end of the pipeline for the non-cavitating flow and at upstream for the cavitating flow. Once the rheological behaviour of HDPE pipes were known, computational simulations have been run in order to describe the hydraulic behaviour of the system for the cavitating pipe flow. The calibrated transient solver is capable of accurately describing the attenuation, dispersion and shape of observed transient pressures. The effects related to the viscoelasticity of HDPE pipes and to the occurrence of vapour pressures during the transient event are discussed.

• Safety and Health at Work
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• 제9권3호
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• pp.277-289
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• 2018

Background: Lancashire Fire and Rescue Service (LFRS), the subject of this evaluative research document employs 1400 people. 80% of employees are operational firefighters and officers whom operate across a range of duty systems and support functions, providing prevention, protection and emergency response to the communities of Lancashire. Methods: The overarching purpose of this epidemiological study is to assess the prevalence of posttraumatic stress disorder (PTSD) amongst operational LFRS personnel and to analyse the effects upon those who may be suffering from it, whether brought about by a single traumatic event or by repeated exposure to traumatic occurrences over a period of time. A combination of primary and secondary research was carried out. Primary data was collated using two recognised clinical questionnaires and statistical analysis was conducted with the aid of the software package SPSS. Results: The findings and statistical analysis showed that out of the 100 people surveyed, 30% of respondents had signs of probable distress. Of this quota, 4% showed symptoms of PTSD. The study considers how an organisation can recognise and manage PTSD and provides recommendations to assist in better recognising and managing the associated risks. Conclusion: Based upon the findings, the authors conclude that the level of PTSD within LFRS is slightly lower than those found in other studies undertaken within the Fire and Rescue Service sector. The paper provides recommendations for future studies and a series of actions for consideration by LFRS senior management to improve PTSD support services for employees.

• Wind and Structures
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• 제35권4호
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• pp.269-285
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• 2022

The pressure-mitigating effects of a high-speed train passing through a tunnel with a partially reduced cross-section are investigated via the numerical approach. A compressible, three-dimensional RNG k-ε turbulence model and a hybrid mesh strategy are adopted to reproduce that event, which is validated by the moving model test. Three step-like tunnel forms and two additional transitions at the tunnel junction are proposed and their aerodynamic performance is compared and scrutinized with a constant cross-sectional tunnel as the benchmark. The results show that the tunnel step is unrelated to the pressure mitigation effects since the case of a double-step tunnel has no advantage in comparison to a single-step tunnel, but the excavated volume is an essential matter. The pressure peaks are reduced at different levels along with the increase of the excavated earth volume and the peaks are either fitted with power or logarithmic function relationships. In addition, the Arc and Oblique-transitions have very limited gaps, and their pressure curves are identical to each other, whereas the Rec-transition leads to relatively lower pressure peaks in C_Pmax, C_Pmin, and ΔC_P, with 5.2%, 4.0%, and 4.1% relieved compared with Oblique-transition. This study could provide guidance for the design of the novel railway tunnel.

• 한방재활의학과학회지
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• 제31권4호
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• pp.157-166
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• 2021

Objectives This study is designed to evaluate the safety of Bojungikgi-tang soft extract in healthy male volunteers. Methods 12 healthy male volunteers were recruited and this study was carried out by a single center. Laboratory test results, vital signs of the volunteers were collected to evaluate safety. According to registration order, the 12 subjects were allocated by serial number. To evaluate safety, blood samples were taken and vital signs were checked 4 times - screening, pre administration, post administration and follow up-during the whole trial. The difference between pre (before medication [0 hr]) and post-administration (after medication [48 hr]) variables was summarized as mean±standard deviation. The normality test was performed using the Kolmogorov-Smirnov test and Shapiro-Wilk test. When the normality is satisfied, the paired t-test is applied. Otherwise, the non-parametric method, Wilcoxon signed rank test is applied. The significance level was p<0.05. The incidence of all adverse effects are shown in percentage. Results In the case of red blood cell, hemoglobin, hematocrit, lymphocytes, neutrophils, protein, γ-glutamyl transpeptidase values, the normality test result of the variable for the difference value before and after the dosing has a significance level <0.05. But most of values did not deviate from the normal range, and the deviation from the normal range could not be regarded as the significance associated with this clinical trial. And adverse event wasn't observed associated with the clinical trial drug. Conclusions Bojungikgi-tang soft extract were considered to be safe for healthy male volunteers.

• 한국항공우주학회지
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• 제34권11호
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• pp.76-83
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• 2006

통신해양기상위성의 통신 탑재체가 겪게 될 우주 방사선 환경을 포획된 입자, 태양 양성자 그리고 우주선으로 구분하여 각각 NASA AP8/AE8 모델, JPL91 모델, 그리고 NRL CREME 모델을 사용하여 전산 모사 하였다. 이러한 우주 방사선 환경이 위성 내 통신 탑재체에 미치는 영향을 추정하기 위해 총 이온화 방사선 효과의 분석에 필요한 Dose-Depth 곡선 및 단일사건효과 발생률 계산에 필요한 LET 스펙트럼 구하였다. 통신 탑재체 내의 각 장치별 차폐 효과 차이를 고려한 총 이온화 방사선 효과의 예측을 위해서 기계 구조 모델을 만든 후 구형 분할 방법을 적용하였다. 이를 통해 통신 탑재체 내 각 장치의 위치별 총 이온화 방사선 효과를 예상하였으며 동일한 외부 방사선 환경에 대해서 차폐 효과에 따라 최고 8배까지 방사선 효과가 다르게 나타났다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 1999년도 Proceedings of International Symposium on Remote Sensing
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• pp.208-213
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• 1999

Space Physics Sensor (SPS) on-board the KOMPSAT-1 consists of the High Energy Particle Detector (HEPD) and the Ionospheric Measurement Sensor (IMS). The HEPD is to characterize the low altitude high energy particle environment and the effects on the microelectronics due to these high energy Particles. It is composed of four sensors: Proton and Electron Spectrometer(PES), Linear Energy Transfer Spectrometer (LET), Total Dose Monitor (TDM), and Single Event Monitor(SEM). 35MeV proton beam from the medical KCCH cyclotron, at Korea Cancer Center Hospital in Seoul, is used to calibrate the PES. Primary proton beam of 35MeV scattered by polypropylene target is converted to various energy Protons according to the elastic collision kinematics. In this calibration, the threshold level of the proton in the PES can be determined and the energy ranges of PES channels are also calibrated.

• Journal of Microbiology and Biotechnology
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• 제20권1호
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• pp.45-53
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• 2010

We have developed an efficient and precise method for genome manipulations in Bacillus subtilis that allows rapid alteration of a gene sequence or multiple gene sequences without altering the chromosome in any other way. In our approach, the Escherichia coli toxin gene mazF, which was used as a counter-selectable marker, was placed under the control of a xylose-inducible expression system and associated with an antibiotic resistance gene to create a "mazF-cassette". A polymerase chain reaction (PCR)-generated fragment, consisting of two homology regions joined to the mazF-cassette, was integrated into the chromosome at the target locus by homologous recombination, using positive selection for antibiotic resistance. Then, the excision of the mazF-cassette from the chromosome by a single-crossover event between two short directly repeated (DR) sequences, included in the design of the PCR products, was achieved by counter-selection of mazF. We used this method efficiently and precisely to deliver a point mutation, to inactivate a specific gene, to delete a large genomic region, and to generate the in-frame deletion with minimal polar effects in the same background.

• Clinical and Experimental Pediatrics
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• 제59권1호
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• pp.35-39
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• 2016

Purpose: This study compared the efficacy and tolerability of intravenous (i.v.) phenobarbital (PHB) and i.v. levetiracetam (LEV) in children with status epilepticus (SE) or acute repetitive seizure (ARS). Methods: The medical records of children (age range, 1 month to 15 years) treated with i.v. PHB or LEV for SE or ARS at our single tertiary center were retrospectively reviewed. Seizure termination was defined as seizure cessation within 30 minutes of infusion completion and no recurrence within 24 hours. Information on the demographic variables, electroencephalography and magnetic resonance imaging findings, previous antiepileptic medications, and adverse events after drug infusion was obtained. Results: The records of 88 patients with SE or ARS (median age, 18 months; 50 treated with PHB and 38 with LEV) were reviewed. The median initial dose of i.v. PHB was 20 mg/kg (range, 10-20 mg/kg) and that of i.v. LEV was 30 mg/kg (range, 20-30 mg/kg). Seizure termination occurred in 57.9% of patients treated with i.v. LEV (22 of 38) and 74.0% treated with i.v. PHB (37 of 50) (P=0.111). The factor associated with seizure termination was the type of event (SE vs. ARS) in each group. Adverse effects were reported in 13.2% of patients treated with i.v. LEV (5 of 38; n=4, aggressive behavior and n=1, vomiting), and 28.0% of patients treated with i.v. PHB (14 of 50). Conclusion: Intravenous LEV was efficacious and safe in children with ARS or SE. Further evaluation is needed to determine the most effective and best-tolerated loading dose of i.v. LEV.

• 한국항공우주학회지
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• 제42권11호
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• pp.981-987
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• 2014

DC/DC 컨버터는 임의의 직류전원을 부하가 요구하는 형태의 직류전원으로 변환시키는 효율이 높은 전력변환기이다. DC/DC 컨버터는 MOSFET(산화물-반도체 전계 효과 트랜지스터), PWM-IC(펄스폭 변조 집적회로) 제어기, 인덕터, 콘덴서 등으로 구성되어있다. MOSFET는 스위치 기능을 수행하는데 코발트 60 ($^{60}Co$) 저준위 감마발생기를 이용한 TID 실험에서 방사선의 영향으로 문턱전압과 항복전압의 변화와 SEGR 실험에 적용된 5종류의 중이온 입자는 MOSFET의 게이트(gate)에 영향을 주어 게이트가 파괴된다. MOSFET의 TID 실험은 40 Krad 까지 수행하였으며, SEGR 실험은 제어보드를 구현한 후 LET(MeV/mg/$cm^2$)별 cross section($cm^2$)을 연구하는데 있다.