• Smart Structures and Systems
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• 제26권2호
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• pp.195-211
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• 2020

Among anti-seismic technologies, base isolation is a very effective means of mitigating damage to structural and nonstructural components, such as equipment. However, most seismic isolation systems are designed for mitigating only horizontal seismic responses because the realization of a vertical isolation system (VIS) is difficult. The difficulty is primarily due to conflicting isolation stiffness demands in the static and dynamic states for a VIS, which requires sufficient rigidity to support the self-weight of the isolated object in the static state, but sufficient flexibility to lengthen the isolation period and uncouple the ground motion in the dynamic state. To overcome this problem, a semi-active VIS, called the piezoelectric inertia-type vertical isolation system (PIVIS), is proposed in this study. PIVIS is composed of a piezoelectric friction damper (PFD) and a leverage mechanism with a counterweight. The counterweight provides an uplifting force in the static state and an extra inertial force in the dynamic state; therefore, the effective vertical stiffness of PIVIS is higher in the static state and lower in the dynamic state. The PFD provides a controllable friction force for PIVIS to further prevent its excessive displacement. For experimental verification, a shaking table test was conducted on a prototype PIVIS controlled by a simple controller. The experimental results well agree with the theoretical results. To further investigate the isolation performance of PIVIS, the seismic responses of PIVIS were simulated numerically by considering 14 vertical ground motions with different characteristics. The responses of PIVIS were compared with those of a traditional VIS and a passive system (PIVIS without control). The numerical results demonstrate that compared with the traditional and passive systems, PIVIS can effectively suppress isolation displacement in all kinds of earthquake with various peak ground accelerations and frequency content while maintaining its isolation efficiency. The proposed system is particularly effective for near-fault earthquakes with long-period components, for which it prevents resonant-like motion.

• Clinical and Experimental Pediatrics
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• 제63권8호
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• pp.314-320
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• 2020

Background: The accumulation of unpaired α-globin chains in patients with β-thalassemia major may clinically create ineffective erythropoiesis, hemolysis, and chronic anemia. Multiple blood transfusions and iron overload cause cellular oxidative damage. However, α-tocopherol, an antioxidant, is a potent scavenger of lipid radicals in the membranes of red blood cells (RBCs) of patients with β-thalassemia major. Purpose: To evaluate the effects of α-tocopherol on hemolysis and oxidative stress markers on the RBC membranes of patients with β-thalassemia major. Methods: Forty subjects included in this randomized controlled trial were allocated to the placebo and α-tocopherol groups. Doses of α-tocopherol were based on Institute of Medicine recommendations: 4-8 years old, 200 mg/day; 9-13 years old, 400 mg/day; 14-18 years old, 600 mg/day. Hemolysis, oxidative stress, and antioxidant variables were evaluated before and after 4-week α-tocopherol or placebo treatment, performed before blood transfusions. Results: Significant enhancements in plasma haptoglobin were noted in the α-tocopherol group (3.01 mg/dL; range, 0.60-42.42 mg/dL; P=0.021). However, there was no significant intergroup difference in osmotic fragility test results; hemopexin, malondialdehyde, reduced glutathione (GSH), or oxidized glutathione (GSSG) levels; or GSH/GSSG ratio. Conclusion: Use of α-tocopherol could indirectly improve hemolysis and haptoglobin levels. However, it played no significant role in oxidative stress or as an endogen antioxidant marker in β-thalassemia major.

• 대한한의학회지
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• 제25권3호
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• pp.137-148
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• 2004

Objectives : To study change of external dermal formation, change of leukocytes in vasculature, change of lipid formation in stratum corneum and distribution of ceramide through administering Sihocheonggan-san (SC) extract on to the control (CON). This study was done through forcing injury to mice's back skin which have lipid protection formation in stratum corneum. Materials and Methods : The CON to which damage was caused intentionally using the external application on the mice's back skin used the SC. The change of leukocytes in vasculature were identified through optima 5.2 and Student's t-test and the results were made into a dermal formation graph. Results : After dispensing SC extract into the CON, dermal injury was decreased. Especially, recover of lipid protection formation, which includes lipid and ceramide in stratum corneum suppressing acute inflammation that some factors are PKC, TNF-α, IL-12B which controlled the secretion of relating inflammatory cytokine, also went onto decrease of angiogenesis, and a decrease of degranulated mast cells was noted. In addition, the decrease of epithelial injury also caused the growth of cells to decrease in stratum basale and cytoclasis. In the vasculature, the leukocytes were also decreased and it could relate to decrease in CON. Conclusions : SC has effect on CON suppressing the dermal injury through recovering of lipid protection formation in stratum corneum.

• 콘크리트학회논문집
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• 제13권4호
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• pp.406-413
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• 2001

본 연구는 기존 원심력 철근콘크리트관의 성능을 향상시킬 수 있는 방법으로 관체 표면을 일정한 두께로 방식 라이닝 모르타르로 처리함으로써 보다 더 내구적인 하수관을 개발하기 위하여 실시하였다. 이를 위해 원심력 철근콘크리트관 제작 시, 동시성형이 가능하고 촉진 증기양생 조건에서도 균열이 발생되지 않는 접착강도가 큰 폴리머 시멘트 모르타르를 제조하였다. 폴리머 시멘트 모르타르를 원심력 철근콘크리트관용 라이닝 재료로 사용하기 위한 기초적 실험결과, 보통 시멘트 모르타르에 비해 역학적 성질 및 내구성이 우수하였으며, 현장적용결과, 동시성형 및 양생조건에 따라 적용될 수 있는 방법은 다양하나, 폴리머의 종류에 관계없이 폴리머 시멘트비를 20% 이하로 하며, 양생온도는 8$0^{\circ}C$이하의 양생조건을 제안할 수 있었다. 또한 현장조건이 가능하면, 2일간 기중양생(2$0^{\circ}C$)을 실시하여 폴리머 시멘트 모르타르 속의 폴리머 필름이 형성된 후, 8$0^{\circ}C$에서 양생시키는 방법이 이상적인 것으로 나타났다.

• 대한간호학회지
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• 제49권3호
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• pp.317-328
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• 2019

Purpose: The purpose of this study was to identify the effect of ghrelin on memory impairment in a rat model of vascular dementia induced by chronic cerebral hypoperfusion. Methods: Randomized controlled groups and the posttest design were used. We established the representative animal model of vascular dementia caused by bilateral common carotid artery occlusion and administered $80{\mu}g/kg$ ghrelin intraperitoneally for 4 weeks. First, behavioral studies were performed to evaluate spatial memory. Second, we used molecular biology techniques to determine whether ghrelin ameliorates the damage to the structure and function of the white matter and hippocampus, which are crucial to learning and memory. Results: Ghrelin improved the spatial memory impairment in the Y-maze and Morris water maze test. In the white matter, demyelination and atrophy of the corpus callosum were significantly decreased in the ghrelin-treated group. In the hippocampus, ghrelin increased the length of hippocampal microvessels and reduced the microvessels pathology. Further, we confirmed angiogenesis enhancement through the fact that ghrelin treatment increased vascular endothelial growth factor (VEGF)-related protein levels, which are the most powerful mediators of angiogenesis in the hippocampus. Conclusion: We found that ghrelin affected the damaged myelin sheaths and microvessels by increasing angiogenesis, which then led to neuroprotection and improved memory function. We suggest that further studies continue to accumulate evidence of the effect of ghrelin. Further, we believe that the development of therapeutic interventions that increase ghrelin may contribute to memory improvement in patients with vascular dementia.

• 대한족부족관절학회지
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• 제26권1호
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• pp.16-21
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• 2022

도수 또는 중력 외회전 부하 방사선 검사는 족관절 양과 유사 골절과 단독 외과 골절을 구별할 수 있는 기준이 된다. 부하 방사선 검사상 내측 관절 간격이 넓어지면 삼각인대 손상을 진단할 수 있고 비골 골절에 대한 수술적 처치가 권장된다. 비골 골절에 대하여 관혈적 정복술 후 Cotton test를 시행하여 경비원위인대가 벌어질 경우 이에 대한 고정을 시행한 후 삼각인대의 봉합술 시행 여부는 술자의 선호도 및 수술장 내 소견에 의하여 결정된다. 삼각인대 봉합술은 내과에 suture anchor를 삽입하고 심부와 천부 삼각인대에 대하여 중첩술 후 내과에 anchor를 통하여 고정함으로써 시행한다. 유일하게 무작위로 시행된 족관절 골절에서의 삼각인대 봉합술의 유용성 평가 연구에서는 삼각인대 봉합술의 유용성에 대하여 긍정적인 결론을 도출하지 못하였으나 연구 자체의 제한점이 많아 해석을 하는 데 있어 한계가 있었다. 추후 이에 대한 심도 있는 연구가 필요하리라 판단된다.

• Journal of Chest Surgery
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• 제37권2호
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• pp.113-118
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• 2004

혈관재건술에 사용되는 냉동 보존된 동종동맥편에 대한 지금까지의 연구는 주로 냉동방법, 냉동전처치, 보존온도에 관심이 집중되어 있었으나, 최근에 해동방법이 균열발생의 중요한 인자가 된다는 연구가 있었다. 이에 저자들은, 같은 조건으로 냉동 보존된 대동맥조직을 서로 다른 두 가지 방법으로 해동시켜, 조직손상 정도를 비교함으로써 이상적인 조직의 해동방법을 알아보고자 하였다. 대상 및 방법: 2,500 g의 토끼에서 대동맥편을 획득한 후, 일반적인 방법에 따라 냉동 보존한 뒤 37$^{\circ}C$의 온수에 급속 해동한 군(RT)과 1$^{\circ}C$/min의 속도로 완속 해동시킨 군(ST)으로 나누고, 각 군에서 apoptosis 발생을 평가하기 위해 각 군의 전체 세포 중 TUNEL (＋) 세포의 비를 비교하였고, 광학현미경하에서 해동된 조직편의 조직학적 특성을 비교 관찰하였다. 결과: 1. TUNEL test상, RT군에서 ST군에 비해 TUNEL (＋) 세포의 비가 유의하게 높았다. 2. 광학현미경하 조직소견상, RT군에서 세포부종과 혈관내피층의 박탈, 소수포 형성, 그리고 이형성세포 등의 소견이 ST군에 비해 더 많이 관찰되었다. 결론: 냉동 보존된 토끼의 대동맥조직에 대한 해동방법의 차이에서, 완속 해동방법이 조직의 형태학적 손상과 apoptosis발생을 감소시켰다. 따라서, 향후 냉동조직을 이용한 이식술에서 술 후 합병증의 발생을 감소시키고 예후를 개선하기 위해서는 기존의 급속 해동하는 방법보다 완속 해동하는 방법의 사용을 고려해야 할 것이다.

• Journal of Korean Neurosurgical Society
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• 제61권3호
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• pp.363-375
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• 2018

Intraoperative monitoring (IOM) utilizes electrophysiological techniques as a surrogate test and evaluation of nervous function while a patient is under general anesthesia. They are increasingly used for procedures, both surgical and endovascular, to avoid injury during an operation, examine neurological tissue to guide the surgery, or to test electrophysiological function to allow for more complete resection or corrections. The application of IOM during pediatric brain tumor resections encompasses a unique set of technical issues. First, obtaining stable and reliable responses in children of different ages requires detailed understanding of normal age-adjusted brain-spine development. Neurophysiology, anatomy, and anthropometry of children are different from those of adults. Second, monitoring of the brain may include risk to eloquent functions and cranial nerve functions that are difficult with the usual neurophysiological techniques. Third, interpretation of signal change requires unique sets of normative values specific for children of that age. Fourth, tumor resection involves multiple considerations including defining tumor type, size, location, pathophysiology that might require maximal removal of lesion or minimal intervention. IOM techniques can be divided into monitoring and mapping. Mapping involves identification of specific neural structures to avoid or minimize injury. Monitoring is continuous acquisition of neural signals to determine the integrity of the full longitudinal path of the neural system of interest. Motor evoked potentials and somatosensory evoked potentials are representative methodologies for monitoring. Free-running electromyography is also used to monitor irritation or damage to the motor nerves in the lower motor neuron level : cranial nerves, roots, and peripheral nerves. For the surgery of infratentorial tumors, in addition to free-running electromyography of the bulbar muscles, brainstem auditory evoked potentials or corticobulbar motor evoked potentials could be combined to prevent injury of the cranial nerves or nucleus. IOM for cerebral tumors can adopt direct cortical stimulation or direct subcortical stimulation to map the corticospinal pathways in the vicinity of lesion. IOM is a diagnostic as well as interventional tool for neurosurgery. To prove clinical evidence of it is not simple. Randomized controlled prospective studies may not be possible due to ethical reasons. However, prospective longitudinal studies confirming prognostic value of IOM are available. Furthermore, oncological outcome has also been shown to be superior in some brain tumors, with IOM. New methodologies of IOM are being developed and clinically applied. This review establishes a composite view of techniques used today, noting differences between adult and pediatric monitoring.

• 한국지반환경공학회 논문집
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• 제18권12호
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• pp.37-45
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• 2017

구조물은 영하의 온도가 유지되는 겨울철에 동상으로 인해 크고 작은 피해가 발생한다. 동상은 동토지반의 가장 대표적인 공학적 특성으로 다양한 동상민감성 판정법이 존재한다. 동상민감성 판정법은 크게 3가지로 분류할 수 있다. 첫 번째 동상민감성은 입도분포를 이용하여 결정된다. 많은 국가들이 지반의 입도분포를 이용해 비교적 간편한 동상민감성 판정법을 현장에 적용하고 있다. 그러나 본 논문에서 몇 가지 시료의 입도분포를 이용해 동상민감성 판정 기준에 적용한 결과에 따르면 입도분포로 토질의 동상민감성을 판정하기에는 다소 무리가 있다. 두 번째로는 동상시험에 의한 동상민감성 판정법이다. 새롭게 개발된 온도제어형 삼축셀을 이용한 동상 실내시험을 통해 동상민감성 기준 신뢰성을 분석하였다. 새롭게 개발된 장비와 시험방법은 기존에 제시하고 있는 동상민감성 판정 기준을 충족하는 것으로 판단되었다. 세 번째로는 복합적인 동상민감성 판정법으로 흙의 입도분포, 분류, 그리고 동상시험을 고려한 복합적인 동상민감성 판정 기준 그래프를 제시하고 있다. 본 논문에서 몇 가지 시료에 대해 복합적인 동상민감성 판정 기준에 적용한 결과 다양한 토질에 대한 추가적인 데이터를 바탕으로 복합적인 동상민감성 판정 그래프를 보완해야 할 것으로 판단되었다.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2003년도 생물공학의 동향(XII)
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• pp.40-44
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• 2003

Soil-borne infectious disease including Pythium aphanidermatum and Rhizoctonia solani causes severe damage to plants, such as cucumber. This soil-borne infectious disease was not controlled effectively by chemical pesticide. Since these diseases spread through the soil, chemical agents are usually ineffective. Instead, biological control, including antagonistic microbe can be used as a preferred control method. An efficient method was developed to select an antagonistic strain to be used as a biological control agent strain. In this new method, surface tension reduction potential of an isolate was included in the ‘decision factor’ in addition to the other factors, such as growth rate, and pathogen inhibition rate. Considering these 3 decision factors by a statistical method, an isolate from soil was selected and was identified as Bacillus sp. GB16. In the pot test, this strain showed the best performance among the isolated strains. The lowest disease incidence rate and fastest seed growth was observed when Bacillus sp. GB16 was used. Therefore this strain was considered as plant growth promoting rhizobacteria (PGPR). The action of surface tension reducing component was deduced as the enhancement of wetting, spreading, and residing of antagonistic strain in the rhizosphere. This result showed that new selection method was significantly effective in selecting the best antagonistic strain for biological control of soil-borne infectious plant pathogen. The antifungal substances against P. aphanidermatum and R. solani were partially purified from the culture filtrates of Bacillus sp. GB16. In this study, lipopeptide possessing antifungal activity was isolated from Bacillus sp. GB16 cultures by various purification procedures and was identified as a surfactin-like lipopeptide based on the Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), high performance liquid chromatography mass spectroscopy (HPLC-MS), and quadrupole time-of-flight (Q-TOF) ESI-MS/MS data. The lipopeptide, named GB16-BS, completely inhibited the growth of Pythium aphanidermatum, Rhizoctonia solani, Penicillium sp., and Botrytis cineria at concentrations of 10 and 50 mg/L, respectively. A novel method to prevent the foaming and to provide oxygen was developed. During the production of surface active agent, such as lipopeptide (surfactin), large amount of foam was produced by aeration. This resulted in the carryover of cells to the outside of the fermentor, which leads to the significant loss of cells. Instead of using cell-toxic antifoaming agents, low amount of hydrogen peroxide was added. Catalase produced by cells converted hydrogen peroxide into oxygen and water. Also addition of corn oil as an oxygen vector as well as antifoaming agent was attempted. In addition, Ca-stearate, a metal soap, was added to enhance the antifoam activity of com oil. These methods could prevent the foaming significantly and maintained high dissolved oxygen in spite of lower aeration and agitation. Using these methods, high cell density, could be achieved with increased lipopeptide productivity. In conclusion to produce an effective biological control agent for soil-borne infectious disease, following strategies were attempted i) effective screening of antagonist by including surface tension as an important decision factor ii) identification of antifungal compound produced from the isolated strain iii) novel oxygenation by $H_2O_2-catalase$ with vegetable oil for antifungal lipopeptide production.