• 대한의생명과학회지
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• 제28권4호
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• pp.211-222
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• 2022

After more than two years of efforts to end the corona pandemic, a gradual recovery is starting in countries with high vaccination rates. Easing public health policies for a full-fledged post-corona era, such as lifting the mandatory use of outdoor mask and quarantine measures in entry have been considered in Korea. However, the continuous emergence of new variants of SARS-CoV-2 and limitations in vaccine efficacy still remain challenging. Fortunately, T cells and memory T cells, which are key components of adaptive immunity appear to contribute substantially in COVID-19 control. SARS-CoV-2 specific CD4⁺/CD8⁺ T cells are induced by natural infection or vaccination, and rapid induction and activation of T cells is mainly associated with viral clearance and attenuated clinical severity. In addition, T cell responses induced by recognition of a wide range of epitopes were minimally affected and conserved against the highly infectious subsets of omicron variants. Polyfunctional SARS-CoV-2 specific T cell memory including stem cell-like memory T cells were also developed in COVID-19 convalescent patients, suggesting long lasting protective T cell immunity. Thus, a robust T-cell immune response appears to serve as a reliable and long-term component of host protection in the context of reduced efficacy of humoral immunity and persistent mutations and/or immune escape.

• 대한핵의학회지
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• 제21권2호
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• pp.167-174
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• 1987

Among noninvasive approaches for the evaluation of left ventricular performance, radionuclide ventriculography (RVG) has been shown to be of particular values. Phase analysis, recently introduced as more objective means for evaluating the temporal sequence of systolic ventricular wall motion than cine image of RVG comprises a pixel by pixel Fourier transformation of the time activity curve of a multiple gated acquisition equilibrium blood pool study. To examine the regional wall motion of ventricles in myocardial infarctions, we evaluated the phase image and histogram constructed for each ventricle by total phase angle range and full width of half maximum (FWHM). This study consisted of 7 normal subjects and 23 subjects with acute myocardial infarction. Contrast ventriculography and coronary angiography was performed in all partients with myocardial infarction. And we compared the result of phase analysis with cine image of RVG and examined the interrelationship between phase analysis and contrast ventriculography with coronary angiography. The results were as follows; 1) The total phase angle range and FWHM of LV phase histogram in myocardial infarction ($86^{\circ}\;and\;32^{\circ}$, repectively) were wider than those in normal control ($38^{\circ}\;and\;18^{\circ}$, respectively p<0.01). 2) RV phase angle range and FWHM in patients with right coronary artery (RCA) occlusion ($79^{\circ}\;and\;37^{\circ}$, respectively) were wider than those in normal control ($39^{\circ}\;and\;18^{\circ}$, respectively p<0.001) and the patients without RCA occlusion ($52^{\circ}\;and\;19^{\circ}$, respectively p<0.01). 3) Phase analysis was more sensitive (95%) than cine image of RVG (70%) for the detection of regional wall motion abnormality of LV.

• Journal of Chest Surgery
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• 제33권6호
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• pp.502-506
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• 2000

Background: Anticoagulant therapy can be required during pregnancy with prosthetic heart valves. Warfarin and heparin provide real protection against thromboembolic phenomena, but they also carry serious risks for the fetus and the mother. In an attempt to identify the best treatment for pregnant women with cardiac valve prostheses who are receiving anticoagulant, we studied 19 pregnancies, the warfarin was discontinued and heparin was administered every 12 hours by subcutaneous injection in doses adjusted to keep the midinterval aPTT in the therapeutic range(at least 2-2.5 control) from the conception to the 12th week of gestation and oral antiocagulant was then administered until the middle of the third trimester in the therapeutic range(at least 2 INR), and heparin therapy was restared until delivery. Also in order to avoid an anticoagulant effect during delivery, it has been our practice to instruct women to either discontinue their heparin injections with the onset of labur or to stop heparin injections 12 hours prior to the elective induction of labour. Result: The outcome of 19 pregnancies managed with above protocol was spontaneous abortion in 3 cases, voluntary termination in 2 cases, premature delivery at 35 weeks in 1 case and delivery at full-term in 14 cases. There was no maternal morbidity and moratality and fetopathy. Conclusion: We conclude that in the second and third trimester of pregnancy, warfarin provide effective protection against thromboembolism, Oral antiocagulant therapy should be avoided in 2 weeks before delivery because of the risk of serious perinatal bleeding caused by the trauma of delivery to the anticoagulated fetus. However, the substitution of heparin at first trimester and 2 weeks before delivery reduce the incidence of complications.

• 광물과 암석
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• 제36권4호
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• pp.337-343
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• 2023

감람석은 철감람석과 마그네슘감람석의 완전고용체로서 암석형 행성, 운석, 소행성, 행성간 먼지 등에 풍부하게 함유되어 있다. 감람석은 조성범위가 매우 넓기 때문에 감람석 함유 시료의 광물정량분석을 위해서는 다양한 조성의 감람석 표준물질을 구비해야 한다. 감람석 표준물질을 전기로와 스테인리스강관을 이용하여 1000~1100 ℃ 범위의 온도에서 합성하였다. 엑스선회절분석에 의하면 시료에 따라 합성불순물과 미반응물이 있으나 전반적으로 전조성 범위를 포함하는 감람석이 합성되었다. 합성 감람석들은 출발물질의 철감람석 몰비에 비례하여 단위포 치수가 선형으로 증가하는 경향을 보였으며, 회절강도도 자연산 감람석과 부합하였다. 그러나 철 함량이 높은 합성 감람석에서 불순물 함량이 증가하는 경향이 있어 아직 모든 합성 감람석을 표준물질로 사용할 수 없으며, 출발물질의 고순도화, 반응시간 및 온도 조절 등의 합성과정 개선이 필요하다.

• 방사성폐기물학회지
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• 제16권3호
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• pp.389-396
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• 2018

국내 가동원전 중 2-루프 가압경수로인 고리1호기는 약 40년 운전한 후, 2017년 6월 18일 영구정지되었다. 영구정지된 고리 1호기는 주요 해체작업을 수행하기전에 계통내 선량률을 저감시켜 작업자피폭을 최소화하기 위한 계통제염을 수행할 예정이다. 일반적으로, 계통제염 범위는 원자로압력용기, 가압기, 증기발생기, 화학 및 체적제어계통, 잔열제거계통 및 원자로 냉각재계통 주요배관을 포함한다. 이러한 계통 및 기기 등을 효율적으로 제염하기 위해서는 제염과정에서 원자로냉각재계통내 유동특성을 평가할 필요가 있다. 계통제염을 위해 순환유량을 제공하는 방법은 다양하나, 본 논문에서는 잔열제거펌프 운전에 따른 고리1호기 원자로냉각재계통내 유동특성을 평가하였다. 잔열제거펌프를 이용한 계통제염은 원자로냉각재 내 유량의 불균형을 초래하여 계통내 기기 및 배관 등에 불순물을 침적시켜 제염이 효율적이지 않다는 것으로 평가되었다.

• 스마트미디어저널
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• 제11권5호
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• pp.75-81
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• 2022

농업의 탄소 중립 및 기후변화 대응을 위해 그동안 내연기관 중심으로 발전해 왔던 농업기계도 온실가스의 배출이 없는 전동 기반의 기술로 전환이 필요하다. 이 연구에서는 농업용 전동 UTV의 진동과 충격을 저감시키고, 차량의 주행안정성과 조종성능을 향상하기 위하여 전동 UTV 서스펜션 설계를 위한 시뮬레이션을 수행하였다. 시뮬레이션은 차체의 공차 하중과 화물을 적재한 하중 상태로 나누어 수행되었다. UTV의 서스펜션 스프링의 가동 범위는 조건 B가 공차상태에서 가동범위 30% 이내의 수준을 나타내고, 적재 중량을 만재한 상태의 UTV 서스펜션 변위는 264mm→121mm로 작아지고, 댐핑속도는 260mm/s→300mm/s로 가동범위 60% 이내의 수준에 있음을 알 수 있었다. 다목적 농작업용을 위한 전동 UTV의 서스펜션은 주행과 지형 적응뿐 아니라 경운과 같은 견인작업에서 농작업 능력을 유지하기 위해 매우 중요한 요인이다. 이 연구의 결과는 전동 UTV를 다양한 농작업에 이용할 수 있도록 적절한 댐핑 범위를 갖는 스프링 파라메터를 결정하는데 유용하게 활용될 수 있을 것이다.

• 대한의용생체공학회:의공학회지
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• 제28권1호
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• pp.36-45
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• 2007

Today Human Personal Trainers are becoming very famous in this health conscious world. They teach user to achieve fitness goals in managed way. Due to their high fee and tight schedule they are unavailable to mass number of people. Another solution to this problem is to develop digital personal trainer portable instrument that may replace human personal trainers. We developed a portable digital exercise trainer device - BIOFIT that manages, monitors and records the user's physical status and workout during exercise session. It guides the user to exercise efficiently for specific fitness goal. It keeps the full exercise program i.e. exercises start date and time, duration, mode, control parameter, intensity in its memory which helps the user in managing his exercise. Exercise program can be downloaded from the internet. During exercise it continuously monitors the user's physiological parameters: heart rate, number of steps walked, and energy consumed. If these parameters do not range within prescribed target zone, the BIOFIT will alarm the user as a feedback to control exercise. The BIOFIT displays these parameters on graphic LCD. During exercise it continuously records the heart rate and number of steps walked every 10 seconds along with exercise date and time. This stored information can be used as treatment for the user by an exercise expert. Real-time ECG monitoring can be viewed wirelessly (RF Communication) on a remote PC.

• Journal of Power Electronics
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• 제10권1호
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• pp.9-13
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• 2010

This paper proposes an input-series-output-parallel connected ZVS full bridge converter with interleaved control for photovoltaic power conditioning systems (PV PCS). The input-series connection enables a fully modular power-system architecture, where low voltage and standard power modules can be connected in any combination at the input and/or at the output, to realize any given specifications. Further, the input-series connection enables the use of low-voltage MOSFETs that are optimized for a very low RDSON, thus, resulting in lower conduction losses. The system costs decrease due to the reduced current, and the volumes of the output filters due to the interleaving technique. A topology for a photovoltaic (PV) dc/dc converter that can dramatically reduce the power rating and increase the efficiency of a PV system by analyzing the PV module characteristics is proposed. The control scheme, consisting of an output voltage loop, a current loop and input voltage balancing loops, is proposed to achieve input voltage sharing and output current sharing. The total PV system is implemented for a 10-kW PV power conditioning system (PCS). This system has a dc/dc converter with a 3.6-kW power rating. It is only one-third of the total PV PCS power. A 3.6-kW prototype PV dc/dc converter is introduced to experimentally verify the proposed topology. In addition, experimental results show that the proposed topology exhibits good performance.

• 대한기계학회논문집A
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• 제34권11호
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• pp.1741-1747
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• 2010

본 연구에서는 원격 조정 매니퓰레이터에 적용할 수 있는 보급형 서비스 로봇 암을 개발하였다. 생체 모방학을 활용하여 새로운 형태의 로봇 손에 대한 개념을 도출하였다. 손가락과 손목은 인체 팔의 근골격에 분석을 통하여 상박에 설치된 와이어와 액추에이터에 의하여 구동된다. DC 모터에 의해 구동되는 스크류-너트 매커니즘을 통하여 구동 케이블에 높은 장력을 발생시킨다. 파지력의 쉬운 제어를 위하여 스크류-너트 메커니즘에 조합 스프링을 적용하였다. 첫 번째 설계에서 손가락 제어 문제, 손가락과 손목 운동의 간섭 문제가 발견되었다. 트리즈의 모순 분석을 통하여 이러한 문제에 대한 해결안을 도출하였다. 두 번째 설계에 대하여 다양한 형태와 무게의 물체에 관하여 파지와 동작 테스트를 시행하였다.

• The Korean Journal of Physiology and Pharmacology
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• 제10권5호
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• pp.243-249
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• 2006

The effect of genistein, widely used as a specific tyrosine kinase inhibitor, on rat brain Kv1.5 channels which were stably expressed in Chinese hamster ovary cells was investigated using the whole-cell patch-clamp technique. Genistein inhibited Kv1.5 currents at +50 mV in a concentration-dependent manner, with an $IC_{50}$ of $54.7{\pm}8.2\;{\mu}M$ and a Hill coefficient of $1.1{\pm}0.2$. Pretreatment of Kv1.5 with protein tyrosine kinase inhibitors ($10\;{\mu}M$ lavendustin A and $100\;{\mu}M$ AG1296) and a tyrosine phosphatase inhibitor ($500\;{\mu}M$ sodium orthovanadate) did not block the inhibitory effect of genistein. The inhibition of Kv1.5 by genistein showed voltage-independence over the full activation voltage range positive to 0 mV. The activation (at +50 mV) kinetics was significantly delayed by genistein: time constant for an activation of $1.4{\pm}0.2$ msec under control conditions and $10.0{\pm}1.5$ msec in the presence of $60\;{\mu}M$ genistein. Genistein also slowed the deactivation of the tail currents, resulting in a crossover phenomenon: a time constant of $11.4{\pm}1.3$ msec and $40.0{\pm}4.2$ msec under control conditions and in the presence of $60\;{\mu}M$ genistein, respectively. Inhibition was reversed by the application of repetitive depolarizing pulses, especially during the early part of the activating pulse. These results suggest that genistein directly inhibits Kv1.5 channels, independent of phosphotyrosine-signaling pathway.