• Current Applied Physics
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• 제18권12호
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• pp.1507-1512
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• 2018

The development of an organic-based aqueous redox flow battery (RFB) using quinone as an electroactive material has attracted great attention recently. This is because this battery is inexpensive, produces high energy density, and is environment friendly in stationary electrical energy storage applications. Herein, we investigate the redox potentials and solubilities of indole-5,6-quinone and indole-4,7-quinone derivatives in terms of the substituent effects of functional groups using theoretical calculations. Our results indicate that full-site substituted derivatives of indolequinone are more useful as active materials compared to single-site substituted derivatives. In particular, our calculations reveal that the substitution of $-PO_3H_2$ and $-SO_3H$ functional groups with multiple polar bonds is very effective in increasing the activity of the aqueous RFB. As a strategy to overcome the limitation that the aqueous solubility is intrinsically low because they are organic molecules, we suggest the substitution of functional groups with multiple polar bonds to the backbones of active organic materials. Among 180 indolequinone derivatives, 17 candidates that meet the redox potential standards ($${\leq_-}0.2V$$ or $${\geq_-}0.9V$$) and eight candidates with solubility exceeding 2 mol/L are identified. Three indolequinone derivatives that satisfy both conditions are finally presented as promising electroactive candidates for an aqueous RFB.

• 한국치위생학회지
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• 제21권1호
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• pp.5-16
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• 2021

Objectives: To evaluate the impact of an oral exercise program including whole-body exercises on oral function in older people. Methods: The participants (aged ≥65 years) were divided into three groups: intervention group I (only oral exercise), intervention group II (oral exercise with whole-body exercises), and control group (no intervention). The oral health status, saliva flow rate, and oral muscle strength were evaluated. Analyses were performed to compare the three groups and identify the changes in the aforementioned parameters before and after the program. Results: The saliva flow rate significantly increased in intervention groups I and II after the program. Oral muscle strength evaluation using the Iow a oral performance instrument showed that the anterior tongue strength increased significantly in intervention group I; the posterior tongue strength and cheek strength also increased but not significantly. The anterior tongue, posterior tongue, and cheek strengths significantly increased in intervention group II. Conclusions: The oral exercise program including whole-body exercises showed positive effects on the saliva flow rate and oral strength. No significant differences were observed in the quality of life related to oral health.

• 한국표면공학회지
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• 제54권4호
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• pp.164-170
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• 2021

Vanadium redox flow batteries (VRFB) have emerged as large-scale energy storage systems (ESS) due to their advantages such as low cross-contamination, long life, and flexible design. However, Hydrogen evolution reaction (HER) in the negative half-cell causes a harmful influence on the performance of the VRFB by consuming current. Moreover, HER hinders V²⁺/V³⁺ redox reaction between electrode and electrolyte by forming a bubble. To address the HER problem, carbon nanotube/graphite felt electrode (CNT/GF) with oxygen functional groups was synthesized through the hydrothermal method in the H₂SO₄ + HNO₃ (3:1) mixed acid solution. These oxygen functional groups on the CNT/GF succeed in suppressing the HER and improving charge transfer for V²⁺/V³⁺ redox reaction. As a result, the oxygen functional group applied electrode exhibited a low overpotential of 0.395 V for V²⁺/V³⁺ redox reaction. Hence, this work could offer a new strategy to design and synthesize effective electrodes for HER suppression and improving the energy density of VRFB.

• 한국정보시스템학회지:정보시스템연구
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• 제15권4호
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• pp.149-170
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• 2006

This research investigates the determinants of the customer's acceptance intuition for the ads on cellular phone. For this purpose, this research set up a model with such variables as entertainment information irritation, credibility, flow experience, attitudes and acceptance intention based on TAM and Flow theory. For the more reasonable and generalizable results, this study targets two different customer groups in Korea and Japan and compare the responses from these two groups using AMOS, the structural equation modeling and a second-generation multi - variant techniques.

• Educational Technology International
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• 제12권2호
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• pp.1-18
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• 2011

This study intends to examine the effects of motivational scaffolding in Computer-Supported Collaborative Learning (CSCL). This study was focused on the following two questions. Do motivational scaffolding lead to positive effects on the process in CSCL? Do motivational scaffolding lead to positive effects on the outcome in CSCL? In order to identify strategies for motivational scaffolding, we reviewed the "Flow Theory." Based on literature reviews, principles and strategies were drawn for the motivational scaffolding. An experimental study was conducted in order to investigate the effects of motivational scaffolding on process and outcome. In this study, 87 undergraduate students were divided into two different groups (control group, experimental group). Motivational scaffolding was provided to experimental group. The process was analyzed by examining learners' satisfaction in process. The outcome was analyzed by examining learners' satisfaction in product, group coherence, and quality of product. The difference between the two groups was statistically significant. From these results, we concluded that motivational scaffolding led to positive effects on process and outcome in CSCL environment.

• 대한소아치과학회지
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• 제29권2호
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• pp.255-261
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• 2002

유동성 복합레진은 치면 열구 전색이나 작은 교합면 우식의 예방적 레진 수복 및 깊은 와동의 이장재로 사용할 수 있으나 이에 대한 임상적 연구는 부족한 실정이다. 본 연구는 유동성 복합레진이 치면 열구 전색, 예방적 레진 수복, 깊은 와동의 이장의 세 가지 임상적 용도로 적용될 경우, 기존의 재료와 비교한 대체가능성과 타당성을 검토할 목적으로, 각 용도에서의 양재료들이 나타내는 미세누출 양상을 비교분석하였다. 교합면이 건전한 120개의 발거된 대구치를 6개의 군으로 나누어 각 군당 20개색 시편을 구성하였다. 제 1군과 2군에는 각각 Concise와 Tetric flow로 치면 열구 전색을, 제 3군에는 Z-100과 Concise, 제 4군에는 Tetric flow로 예방적 레진 수복을 시행하였으며, 제 5군에는 Vitrebond, 제 6군에는 Tetric flow를 이장재로 이용하여 sandwich technique 수복을 시행하였다. 100회의 열 순환 및 색소 침투후 색소 침투 정도를 관찰하고 미세누출 정도를 판단하여 비교, 분석한 결과 다음과 같은 결론을 얻었다. 1. 열구 전색재인 Concise와 유동성 복합레진인 Tetric flow로 각각 치면 열구 전색을 시행한 경우 미세누출의 차이가 나타나지 않았다(p>0.05). 2. 복합레진인 Z-100과 열구전색재인 Concise로 예방적 레진 수복을 시행한 군과 유동성 복합레진인 Tetric flow 단일 재료로 수복한 군 간에도 미세누출의 차이는 없었다(p>0.05). 3. 이장재로 Resin-modified glass ionomer cement 인 Vitrebond와 유동성 복합레진인 Tetric flow를 사용하여 sandwich technique으로 복합레진 수복을 시행한 경우에도 양 군간에 미세누출의 차이는 나타나지 않았다(p>0.05).

• Journal of Chest Surgery
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• 제18권2호
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• pp.182-192
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• 1985

[here are so many reports that pulsatile blood flow provides physiologic organ perfusions during cardiopulmonary bypass. So, we compared the recent 30 cases undergoing cardiac surgery by Cobe-Stckert pulsatile roller pump with another 30 cases by Polystan nonpulsatile roller pump. Pulsatile flow was applied during aortic-cross clamping period when synchronized to internal EKG simulator, and perfusion mode was changed to continuous nonpulsatile flow after declamping of aorta. Age, sex, weight, and disease entities were comparable and operative techniques were similar between two groups. 1. There were no differences in average ACC time, ECC time, and Operation time. 2. Postoperative artificial respiration time was 6hrs 30mins in nonpulsatile group and 4hrs 48mins in pulsatile group, and detubation time after ventilator weaning was 2hrs 44mins in nonpulsatile group and 1hrs 43mins in pulsatile group. 3. Average pulse pressure was 8mmHg in nonpulsatile group and 55mmHg in pulsatile group, and a mean arterial pressure was 66.0mmHg in nonpulsatile group and 60.7mmHg in pulsatile group. 4. Mean urine-output during ACC;ECC period was 9.717.3;9.913.2ml/kg/hr in nonpulsatile group and 14.215.0;15.817.5 in pulsatile group [p<0, 05], and thereafter progressive decrease of differences in urine output between two groups until POD 2, and lesser amounts of diuretics was needed in pulsatile group during same postoperative period. Serum BUN/Cr level showed no specific difference and urine concentration power was well preserved in both groups. 5. Plasma proteins and other Enzymes showed no differences between two groups, but serum GOT/GPT level was higher in nonpulsatile group till POD 2. 6. Serum Electrolytes showed no differences between two groups. 7. WBC, RBC, Platelet counts, Hgb and Hct were not different and Coagulogram was well preserved in both groups. 8. Plasma free Hgb level was 7.09mg% in pulsatile group compared with 3.48mg% in pulsatile group on POD 1 but was normalized on POD 2. Gross hemoglobinuria after ECC was noted in 6 cases [20%] of pulsatile group and 4 cases [13%] of nonpulsatile group. 9. In both groups, most patients were included in NYHA class III to IV [28 cases;93% in nonpulsatile group, 22 cases;73% in pulsatile group] preoperatively, and well improved to class I to 11[22 cases; 73% in nonpulsatile group, 30 cases; 100% in pulsatile group] postoperatively. There were 7 operative mortalities in nonpulsatile group only, which were 5 cases of TOF with hepatic failure, 1 case of multiple VSDs with low out-put syndrome, and 1 case of mitral valvular heart disease with cardiomyopathy. We concluded that the new, commercially available Cobe-Stckert pulsatile roller pump device was safe, simple, and reliable.

• 대한기계학회논문집B
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• 제27권8호
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• pp.1033-1041
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• 2003

Two-phase flow pattern data during horizontal in-tube flow boiling are presented for pure and mixed refrigerants of R134a and Rl23, The flow pattern is observed through tubular sight glasses located at inlet and outlet of the test section, which is made of a stainless steel tube, 2m long with 10mm I.D., 1.5mm wall thickness. The obtained results are compared with the available various correlations for flow pattern. The flow pattern map of Hashizume was in good agreement with the present data except the region of low mass velocity. Weisman flow pattern map was also known to satisfactorily predict data for refrigerants in the region of annular flow. In this study, the flow pattern are simply classified into two groups; stratified(including intermittent, stratified and stratified-wavy) flow and annular flow. The transition quality from stratified to annular flow was obtained by modifying the liquid Froude number.

• Journal of Chest Surgery
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• 제49권3호
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• pp.145-150
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• 2016

Background: Extracorporeal circulation (ECC) can induce alterations in blood viscoelasticity and cause red blood cell (RBC) aggregation. In this study, the authors evaluated the effects of pump flow pulsatility on blood viscoelasticity and RBC aggregation. Methods: Mongrel dogs were randomly assigned to two groups: a nonpulsatile pump group (n=6) or a pulsatile pump group (n=6). After ECC was started at a pump flow rate of 80 mL/kg/min, cardiac fibrillation was induced. Blood sampling was performed before and at 1, 2, and 3 hours after ECC commencement. To eliminate bias induced by hematocrit and plasma, all blood samples were adjusted to a hematocrit of 45% using baseline plasma. Blood viscoelasticity, plasma viscosity, hematocrit, arterial blood gas analysis, central venous $O_2$ saturation, and lactate were measured. Results: The blood viscosity and aggregation index decreased abruptly 1 hour after ECC and then remained low during ECC in both groups, but blood elasticity did not change during ECC. Blood viscosity, blood elasticity, plasma viscosity, and the aggregation index were not significantly different in the groups at any time. Hematocrit decreased abruptly 1 hour after ECC in both groups due to dilution by the priming solution used. Conclusion: After ECC, blood viscoelasticity and RBC aggregation were not different in the pulsatile and nonpulsatile groups in the adult dog model. Furthermore, pulsatile flow did not have a more harmful effect on blood viscoelasticity or RBC aggregation than nonpulsatile flow.

• 한국체육학회지인문사회과학편
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• 제54권1호
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• pp.535-544
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• 2015

이 연구는 노인 여성에 대한 저항성 훈련 시 혈류제한(blood flow restriction)을 적용할 경우 저강도 운동을 통해서도 하지의 근력과 근육량을 효과적으로 향상시킬 수 있는지를 검증하기 위해 수행되었다. 총 16명의 노인 여성(연령 70.9±4.6)을 저강도 운동 집단(30% 1 RM, n=8)과 고강도 운동 집단(75% 1 RM, n=8)으로 구분하였다. 두 그룹 모두 우측 하지는 대퇴 근위부에 혈류제한용 커프(cuff)를 착용한 상태에서, 좌측 하지는 혈류제한 장치 없이 동일한 운동을 수행한 후 트레이닝 전·후의 근육량과 근력 변화를 분석하였다. 저항성 운동 프로그램은 leg press, leg extension, leg curl을 12회 반복으로 3세트씩 총 10주간 주 2회 실시하였다. 자기공명영상분석기(MRI)로 근 횡단면적(CSA)과 근육량을 산출하였으며, 체성분 변화는 이중에너지 방사흡수 계측기(DEXA), 근력 평가는 등속성 운동 장비(HUMAC Norm)를 이용하였다. 연구를 통해 10주간의 저항성 훈련 후 혈류제한을 적용한 상태에서 고강도 운동을 수행한 집단의 대퇴사두근 근횡단면적(15.2%, p<.001)과 근육량(13.8%, p<.001)이 증가하였으며 이러한 긍정적 변화는 혈류제한 상태에서 저강도로 운동한 집단의 횡단면적(9.8%, p<.001)과 근육량(6.9%, p<.001) 변화에서도 확인할 수 있었다. 한편, 근력은 운동 수행만으로도 향상되었으나 혈류를 제한할 경우 향상도가 더 높은 경향을 보였다. 따라서 이 연구는 혈류제한을 적용할 경우 저항성 운동을 저강도로 수행하더라도 노인 여성의 근 비대와 근력 증가에 효과적으로 작용할 가능성을 시사한다.