• Journal of the Korean neurological association
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• v.36 no.4
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• pp.294-301
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• 2018

Background: Neuroimaging can play a crucial role in discovering potential abnormalities to cause secondary headache. There has been a progress in the fields of headache diagnosis and neuroimaging in the past two decades. We sought to investigate neuroimaging findings according to headache disorders, age, sex, and imaging modalities in first-visit headache patients. Methods: We used data of consecutive first-visit headache patients from 9 university and 2 general referral hospitals. The International Classification of Headache Disorders, third edition, beta version was used in headache diagnosis. We finally enrolled 1,080 patients undertook neuroimaging in this study. Results: Among 1,080 patients (mean age: $47.7{\pm}14.3$, female: 60.8%), proportions of headache diagnosis were as follows: primary headaches, n=926 (85.7%); secondary headaches, n=110 (10.2%); and cranial neuropathies and other headaches, n=43 (4.1%). Of them, 591 patients (54.7%) received magnetic resonance imaging (MRI). Neuroimaging abnormalities were found in 232 patients (21.5%), and their proportions were higher in older age groups and male sex. Chronic cerebral ischemia was the most common finding (n=88, 8.1%), whereas 76 patients (7.0%) were found to have clinically significant abnormalities such as primary brain tumor, cancer metastasis, and headache-relevant cerebrovascular disease. Patients underwent MRI were four times more likely to have neuroimaging abnormalities than those underwent computed tomography (33.3% vs. 7.2%, p<0.001). Conclusions: In this study, the findings of neuroimaging differed according to headache disorders, age, sex, and imaging modalities. MRI can be a preferable neuroimaging modality to identify potential causes of headache.

• Journal of the Korean Burn Society
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• v.22 no.2
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• pp.66-70
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• 2019

Purpose: The necrotizing fasciitis is a terrifying infectious disease that can rapidly spreads to surrounding tissues when fascia is infected and it can cause sepsis to death if not properly diagnosed and treated. The purpose of this study is to investigate the characteristics, causes, and treatment methods of necrotizing fasciitis in Korea through reviewing patients admitted to our burn center. Methods: 21 patients with necrotizing fasciitis were selected for this study among those inpatients with electronic medical records (EMR) admitted to Hallym University Hangang Sacred Heart Medical Center from Jan 1, 2008 to June 30, 2019. The medical records and wound photos of those 21 selected subjects were reviewed. Results: There were 13 male and 8 female patients and mean age was 58.76 years old. 13 of 21 subjects were survived and 8 died (38% mortality rate). The surgical treatments performed were I&D, fasciotomy, debridement, allograft, burring, STSG, flap, and amputation. The most common causes were burns in 9 subjects (6 contact burns) and cellulitis occurred on skins in 5 subjects. And other various causes were observed as fournier's gangrene, stab wound, intramuscular injection, tumor and bleu toe syndrome (toe necrosis). The infected areas were 11 feet and legs, 7 hips, 3 abdomen and trunk in 21 subjects. Of the 8 deaths, 3 were infected in feet and legs, 2 were infected in hips, and 2 were infected in abdomen and trunk. As for underlying diseases, 12 patients with hypertension or diabetes were the highest and others such as cancer and stroke were found. Conclusion: The only method to increase the survival rate is to 'suspect' the disease as much as possible and perform early extensive excision. It is advisable to treat the disease by the burn center to properly provide adequate and optimal wound management, infection control, medical care and nutritional supports.

• Journal of the Korean Geotechnical Society
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• v.34 no.2
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• pp.55-63
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• 2018

In order to support the load of the train with enough stiffness, a study on an effective method for the characterization of the stiffness of the compacted subgrade is required. In this study, the crosshole-type dynamic cone penetrometer (CDCP) is used for the stiffness characterization of the subgrade along the depth. For the application of the CDCP test, three points of compacted subgrades are selected as the study sites. For the study sites, CDCP test, in-situ density test, and light falling weight deflectometer (LFWD) test are conducted. As the results of CDCP tests, shear wave velocity profiles are obtained by using the travel times and the travel distances of the shear waves along the depth. In addition, maximum shear modulus ($G_{max}$) profiles are estimated by using the density of the subgrades and the shear wave velocity profiles. The averaged maximum shear moduli at each testing point are highly correlated with the dynamic deflection moduli ($E_{vd}$) determined by LFWD tests. Therefore, a reliable stiffness characterization of the subgrade can be conducted by using CDCP tests. In addition, because CDCP characterizes the stiffness of the subgrade along the depth rather than a representative value, CDCP test may be effectively used for the stiffness characterization of the subgrade.

• Journal of The Korean Association of Information Education
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• v.26 no.2
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• pp.129-140
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• 2022

Our society is undergoing rapid changes due to COVID-19, and in particular, online learning using digital technology is being tried in various forms in the educational field. A change has occurred. However, the limitations of distance learning, such as reduced learning immersion in non-face-to-face educational situations, lack of interaction between teachers and learners, and lower basic academic ability, are constantly being raised, and an appropriate educational strategy is needed to solve these problems. This study focused on the concept of 'Metaverse' based on the interaction between the virtual world and the real world, and tried to verify the effectiveness of educational activities based on it. In detail, we propose an educational framework for realizing flipped learning in the Metaverse Virtual Classroom, and a frame developed by measuring the learning immersion of a single group with a teaching/learning program developed based on this. The effectiveness of the work was verified. When the metaverse platform-based flip learning framework and education program proposed in this study were applied, it was confirmed that learners' immersion in learning was improved.

• Journal of the Korean Burn Society
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• v.22 no.1
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• pp.1-9
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• 2019

Purpose: The aim of this study was to investigate the characteristics of Acute Kidney Injury Network (AKIN)-defined nephrotoxicity in patients undergoing intravenous colistimethate sodium (CMS) therapy for major burns. Methods: This retrospective study included burn patients who received more than 48 h of intravenous CMS between September 2009 and December 2015. Data collection was performed using the institution's electronic medical record system. Patients assigned to the developed nephrotoxic group experienced aggravation of current AKIN stage during CMS treatment; those assigned to the non-nephrotoxic group experienced no change in current or exhibited improved AKIN stage during CMS therapy. Results: A total of 306 patients were included in this study. All patients were grouped according to AKIN stage: AKIN 0 (n=152); AKIN 1 (n=6); AKIN 2 (n=9); AKIN 3 (n=139). The baseline creatinine (Cr) level was 0.73 mg/dL. The incidence of nephrotoxicity was 50.3% according to AKIN stage; overall mortality was 45.8%. The non-nephrotoxic group consisted of 127 (74.7%) patients and 43 (25.3%) were in the developed nephrotoxic group. In patients requiring continuous renal replacement therapy (CRRT), baseline Cr level was 0.83 mg/dL, pre-CMS Cr level was 1.17 mg/dL, and post-CMS Cr level was 1.34 mg/dL. Conclusion: CMS can be administered without signs of nephrotoxicity for a certain period (approximately 1 week), it can be used relatively safely for 2 weeks. Application of CMS is a reasonable option for treating infections caused by multi-drug resistant gram-negative bacteria in patients with major burns. The caution should be exercised nevertheless.

• Journal of the Korea Concrete Institute
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• v.22 no.3
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• pp.399-407
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• 2010

The flexural behaviors of two types of beam members exposed to freeze-thaw cycles were evaluated. This study aims to examine the effect of freeze-thaw cycles on the behavior characteristics of reinforced concrete (RC) beams. For the purpose, a part of the beam specimens were damaged until yielding of tension reinforcement was reached, before they were exposed to 150 and 300 cycles of freeze-thaw. Cyclic tests, as well as monotonic tests, were conducted to evaluate the stiffness degradation characteristics when same cycle is repeated. The material tests showed that relative dynamic modulus of concrete exposed to 300 cycles of freeze-thaw moderately decreased to 86.8% of normal concrete, indicating that concrete used in this study has good durability against freeze and thaw damage. The results of monotonic tests showed reduction of flexural strength, ductility and stiffness of the beam specimens exposed to freeze-thaw cycles compared with those of the control speciments. In particular, BDF13 specimens, which had been subjected to artificial cracking damage, did not showed enough flexural strength to satisfy nominal moment required by current concrete structure design code. In the monotonic tests results, BF75 specimens exposed to freeze-thaw cycles showed 10% or more cyclic stiffness degradation. Therefore, it was thought that deformation of concrete in compression have to be considered in design process of members under cyclic load, such as seismic device.

• International Journal of Highway Engineering
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• v.10 no.2
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• pp.1-13
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• 2008

This study presents a case study of condition evaluation of various asphalt pavement sections to estimate performance lives. The pavement surface conditions including cracking and rutting are first evaluated using a automatic pavement analyzer, ARAN. HPCI(Highway Pavement Condition Index) values are estimated using the pavement surface distress data. It is observed from the pavement distress survey that the major distress type of the sections is top-down cracking. The modulus value of each pavement layer is back-calculated from the defection data obtained from a FWD(Falling Weight Deflectometer) and compared with the laboratory measured dynamic modulus values. Remaining lives of the various pavement sections are estimated based on a mechanistic-empirical approach and AAHTO 1993 design guide. The structural capacities of the all pavement sections based on the two approaches are strong enough to maintain the pavement sections for the rest of design life. Since the major distress type is top-down cracking, the remaining lives of the pavement sections are estimated based on HPCI and existing performance database of highway pavements. To evaluate the causes of premature pavement distress, various material properties, such as air void, asphalt binder content, aggregate gradation, dynamic modulus and fatigue resistance, are measured from the field cores. It is impossible to accurately estimate the binder contents of field samples using the ignition method. It is concluded from the laboratory tests that the premature top down cracking is mainly due to insufficient compaction and inadequate aggregate gradation.

• The Journal of Engineering Geology
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• v.8 no.2
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• pp.131-143
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• 1998

The study area, Beulgok-myon Nonsan-goon Chungcheongnan-do is consist of Changri slate(Och, okcheon system), lithic tuff(Kslt, kyoungsang system), granite (Kqb, kyoungsang system) and quartz porphyry(Kgf, kyoungsang system). More than 3000 joints were measured and classified by direction. Main dipdirection/dips of Kqb are 228~257/73~88, 010~150/70~85, Och are 134~164/40~90, 214~249/55~89, Kslt are 291~332/75~82, 235~241/73~71. But Kgf are not appeared distinct directions of joint. In field, p-wave velocities(Vp) are measured on the bed rock. Vp of Kgf are $5000m(240^{\circ})~2380(360^{\circ})m/s$, Kqb are $3846(210^{\circ})~1408(150^{\circ})m/s$, Kslt are $5000(360^{\circ})~2323(150^{\circ})m/s$ and Och are $6657(180^{\circ})~2000(030^{\circ})m/s$. Also P-wave velocities on specimen are measured. It is slightely higher than it's measured on the bed rock. For engineering properties of rock, we measured Poisson's ratio, rigidity, Young's modulus and bulk modulus by dynamic method.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.3
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• pp.251-260
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• 2003

A three dimensional (3-D) method of analysis is presented for determining the free vibration frequencies and mode shapes of deep, tapered rods and beams with circular cross section. Unlike conventional rod and beam theories, which are mathematically one-dimensional (1-D), the present method is based upon the 3-D dynamic equations of elasticity. Displacement components u/sup r/, u/sub θ/ and u/sub z/, in the radial, circumferential, and axial directions, respectively, are taken to be sinusoidal in time, periodic in , and algebraic polynomials in the r and z directions. Potential (strain) and kinetic energies of the rods and beams are formulated, the Ritz method is used to solve the eigenvalue problem, thus yielding upper bound values of the frequencies by minimizing the frequencies. As the degree of the polynomials is increased, frequencies converge to the exact values. Convergence to four-digit exactitude is demonstrated for the first five frequencies of the rods and beams. Novel numerical results are tabulated for nine different tapered rods and beams with linear, quadratic, and cubic variations of radial thickness in the axial direction using the 3D theory. Comparisons are also made with results for linearly tapered beams from 1-D classical Euler-Bernoulli beam theory.

• Magazine of the Korean Society of Agricultural Engineers
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• v.39 no.1
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• pp.75-82
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• 1997

건설기술과 산업의 발전에 따라 구조물은 대형화되어 가고, 건설공사의 급격한 팽창으로 골재 수용량이 급증함에 따라 천연골재자원은 점차 부족현상을 면치 못할 처지에 있다. 또한, 무리한 천연골재의 채취는 자연환경을 훼손시킬 뿐만 아니라 자연보호 측면에서도 심각한 공해문제로 대두되고 있어 공급량 부족현상은 날로 심화되고 있다. 이에 세계 몇몇 나라에세는 산업부산물을 이용한 골재 생산으로 공해예방과 폐기물 활용방법을 연구하고 있다. 산업부산물중 플라이 애쉬 생산량은 전 세계적으로 매년 약 2억여톤에 달하고 있으나 이중 일부만 활용되고 있는 실정이다. 이와같은 부산물을 활용하기 위한 일환으로 산업부산물인 PFA(Pulverized Fuel Ash)로 만든 인공경량골재의 년생산량이 영국은 600,000$m^3$, 미국은 300,000$m^3$이며, 매년 증가주세에 있다. 고성능 경량골재 콘크리트는 단위중량의 증가없이 내구성과 강도를 향상시켜 실용화 측면에서 경제적인 효과가 있으며, 플라이 애쉬로 만든 경량골재는 시멘트와의 친화력이나 접착면에서 우수한 것으로 알려져 있다. 본 시험에 사용한 골재는 플라이 애쉬로 만든 인공경량 조골재와 강모래이고, 결합제로서 프틀랜드 시멘트를 사용하였다. 부수적인 결합재로서는 플라이 애쉬, 슬래그, 실리카 흄을 사용하였으며, 고성능 경량골재 콘크리트를 개발코자 재령 28일과 180일의 압축강도가 각각 50MPa와 60MPa가 되도록 배합설계를 하였다. 본 연구에서는 플라이 애쉬, 슬래그, 시리카 흄과 같은 산업부산물을 혼입했을때 경량골재 콘크리트의 압축강도, 휨강도, 동탄성계수, 공극체적, 공극률, 단위중량, 공극 크기별 분포등의 변화를 실험적으로 구명하여 재반 구조용 콘크리트에 활용하기 위한 기초자료를 마련코저 한다.있어 특정한 발육단계의 난포 사망기전을 연구하기 어렵다. 또한 난포는 생체 내에서 다양한 호르몬을 동시에 분비하기 때문에 특정한 난소국부호르몬이 사망기전에 미치는 영향을 조사하기 힘든 점이 있다. 최근 들어 난포체외배양이 다양하게 개발되면서, 이러한 어려운 점을 극복할 수 있게 되었다. 본 논문은 각 발육단계의 난포를 절단해 체외배양하면서, apoptosis DNA 절단 현상을 이용하여 각종 난소국부 호르몬들이 난포발육단계별로 사망기전에 미치는 영향을 요약해 보였다. 난포는 발육하면서 점차 복잡한 호르몬 경로를 생존을 위해 필요로 한다. Prevulatory난포생존에 필요한 난소국부호르몬들은 early antral 단계의 난포에서는 그 미치는 영향이 감소되다가 preantral단계의 난포에서는 영향을 전혀 미치지 못했다. 단지 예외는 cGMP처리로써, 세포내 cGMP수준을 일정하게 유지시켜주는 것이 난포발육단계에 무관하게 생존에 중요한 인자로, 장래 연구는 난포 세포내의 cGMP수준을 조절하는 기작을 규명하는데 있을 것이다.인정되지 않았다. 7. 농지보전 처리구인 배수구와 초생수로구는 비처리구에 비해 낮은 침두 유출량과 낮은 토양유실량을 나타내었다.구보다 14% 절감되는 것으로 나타났다.작용하는 것으로 사료된다.된다.정량 분석한 결과이다. 시편의 조성은 33.6 at% U, 66.4 at% O의 결과를 얻었다. 산화물 핵연료의 표면 관찰 및 정량 분석 시험시 시편 표면을 전도성 물질로 증착시키지 않고, Silver Paint 에 시편을 접착하는 방법으로도 만족한 시험 결과를 얻을 수 있었다.째, 회복기 중에 일어나는 입자들의 유입은 자기폭풍의 지속시간을 연장시키는 경향을 보이며 큰 자기폭풍일수록 현저했다. 주상에서 관측된 이러한 특성은 서브스톰 확장기 활동이 자기폭풍의 발달과 밀접한 관계가