• Journal of Cardiovascular Imaging
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• 제26권4호
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• pp.229-237
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• 2018

BACKGROUND: Statins are thought to have little effect on the progression of aortic stenosis, but the data on their role in patients with aortic valve sclerosis (AVS) are limited and inconsistent. METHODS: We retrospectively analyzed 541 consecutive patients (214 men, age: $70{\pm}11$ years) with AVS. Each patient underwent two or more electrocardiography examinations at least 6 months apart at Kangwon National University Hospital from August 2010 to August 2015. AVS is defined as irregular thickening of the leaflets, focal increases in echogenicity and minimal elevation of the peak aortic valve velocity (> 1.5 and < 2 m/s). The progression rate of AVS was expressed as the increase in peak velocity per year (m/s/yr). RESULTS: The mean follow-up duration was $24.9{\pm}13.3$ months in the statin-treated group and $24.1{\pm}12.4$ months in the non-statin-treated group (p = 0.460). There were no differences between the statin-treated and non-statin-treated groups in mean age, gender or smoking status. Relative to the non-statin-treated group, a higher number of patients in the statin-treated group had hypertension, diabetes, ischemic heart disease, and stroke. The progression rate of AVS did not differ between the statin-treated and non-statin-treated groups ($0.012{\pm}0.340m/s/yr$ vs. $0.014{\pm}0.245m/s/yr$, p = 0.956). Multivariate analysis showed initial peak aortic jet velocity was significantly associated with AVS progression (${\beta}=0.153$, p = 0.009). CONCLUSIONS: Our study demonstrated that statins had no effect on the progression of AVS. However, well-designed studies are needed to define the prognosis and management of AVS.

• 한국산학기술학회논문지
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• 제13권6호
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• pp.2664-2671
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• 2012

본 연구는 노인들의 신체적 특성이 보행 속도에 어떠한 영향을 미치는지 알아보기 위하여 시행되었다. 연구대상자는 보조도구의 사용에 관계없이 독립보행이 가능한 노인 77명(남 38명, 여자 39명)을 대상으로 하였다. 상관분석과 단계적 다중 선형 회귀분석을 사용하여 신체적 특성(연령, 성별, 신장, 체중, 신체질량지수, 근육량, 허리/엉덩이둘레비, 심박수, 폐활량, 유연성, 최대산소섭취량, 눈감고 한발 서기)과 하지 근력(슬관절 신전근, 슬관절 굴곡근)이 보행 속도와 어떠한 관련성이 있는지 분석하였다. 보행 속도는 연령, 신장, 폐활량, 눈감고 한발 서기 시간, 슬관절 굴곡근 및 신전근의 근력과 상관관계가 있었다. 또한 슬관절 굴곡근에 의해 보행 속도는 27%로 설명력을 가지고 있었으며, 슬관절 신전근 변수가 추가되었을 때 설명력은 32%로 높아졌다. 이러한 결과는 노인의 보행 속도가 하지의 근력과 다양한 신체적 특성에 영향을 받는다는 것을 의미한다.

• 한국자연치유학회지
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• 제7권1호
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• pp.1-9
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• 2018

제주 곶자왈 삼림욕 후 혈관연령타입, 혈관연령지수, 심박세기, 혈관탄성도, 심장의 잔혈량 및 평균맥박의 비율 변화를 조사하기 위하여 대조군은 14명과 실험군은 49명을 대상으로 손끝의 맥파 측정기로 측정하여 변화를 통계적으로 분석 연구하는 것이 목적이었다. 연구결과에서는 혈관연령타입, 혈관연령지수, 심박세기(b/a 비율), 심장의 잔혈량(d/a 비율), 평균맥박의 비율의 변화는 대조군은 사전·사후의 평균치 차이는 유의성이 없었으나, 실험군에서는 유의성이 있었으며(p<.011), 사후의 분산분석에서는 그룹 내 및 간에서도 유의한 차이를 보였다(p<.011). 혈관탄성도(c/a 비율)변화는 대조군과 실험군은 사전 사후의 평균치 차이는 유의성이 없었으며, 사후의 평균 측정치의 분산분석에서는 그룹 내에서는 유의한 차이가 있었으나, 그룹 간에서는 유의성이 없었다. 평균맥박의 변화는 그룹 내에서는 유의성이 없었으나, 그룹 간에는 유의성이 있었다. 결론적으로 제주 곶자왈숲에서 2시간 이상의 삼림욕 후에는 심박동변이(HRV)가 유의성이 높게 나타나서 b/a, c/a, d/a, e/a 비율 변이가 HRV의 변화 측정에 유용한 도구라 생각하며, 삼림욕이 심혈관의 건강 유지에 우수한 자연요법이라 판단한다.

• 대한의용생체공학회:의공학회지
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• 제17권1호
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• pp.49-60
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• 1996

An experimental investigation was performed under steady flow condition to assess hydrodynamic performance of floating-type monoleaflet polymer valves (MLPV) withdifferent leaflet thickness. The St. Jude Medical valve (SJMV) was also used for comparison test. Pressure drops of MLPVS are larger than those for other types of polymer valves and mechanical valves. Furthermore, the thicker is the leaflet thickness of the polymer valve, the larger are the corresponding pressure drop. The velocity profiles for MLPs reveal a large reversed flow region downward to the valve position. The maximum wall shear stresses of MLPVS at a flow rate of $30{\ell}$/min are in the range 50-130 dyn/$cm^2$, and the corresponding maximum Reynolds shear stresses are in the range of 100-500 dyn/$cm^2$, respectively, which are beyond the allowable limit clinically. In contrast, floating-type monoleaflet polymer valves show better hydrodynamic performance in leakage volume. From the designing point of view, it may be concluded that the optimum thickness of leaflet for better hydrodynamic performance is one of the Important parameters.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1995년도 춘계학술대회
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• pp.241-246
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• 1995

An experimental investigation was performed under steady flow condition to assess hydrodynamic performance of floating-type monoleaflet polymer valves (MLPV) with different leaflet thickness. The St. Jude Medical valve (SJMV) was also used for comparison tests. Pressure drops of MLPVs are larger than those for other types of polymer valves and mechanical valves. Furthermore, the thicker is the leaflet thickness of a polymer valve, the larger arc the corresponding press drop. The velocity profiles for MLPV reveal a large reversed flow region downward to the valve position. The maximum wall shear stresses of MLPVs at a flow rate of 30 l/min are in the range $54-130\;dyn/cm^2$, and the corresponding maximum. Reynolds shear stresses are in the range of $100-500\;dyn/cm^2$, respectively. Both arc beyond the allowable limit clinically. In contrast, floating-type monoleaflet polymer valves show better hydrodynamic performance in leakage volume. From the designing point of view, it can be concluded that the optimum thickness of leaflet for better hydrodynamic performance is one of the important parameters.

• 대한통합의학회지
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• 제11권4호
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• pp.27-39
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• 2023

Purpose : The aim of this study was to identify the influence of transient isokinetic exercise on cardiac autonomic modulation and muscle properties in healthy male subjects. Methods : Twenty-eight healthy males underwent isokinetic exercise of both knee joints using a Biodex systems 3 isokinetic dynamometer with an angular velocity of 60 °/sec. The changes in activity of the autonomic nervous system, as determined by heart rate variability (HRV), and in muscle properties were evaluated at three times: pre-exercise, immediately post-exercise, and 10 min post-exercise. Results : The time domain analysis of HRV revealed significant changes in the beat count and mean and minimal heart rate (HR) measured at pre-exercise, immediately post-exercise, and 10 min post-exercise (p<.001). The beat count and mean HR were markedly increased immediately post-exercise compared to pre-exercise, but then significantly decreased at 10 min post-exercise (p<.001). All parameters of the frequency domain were significantly altered by isokinetic exercise (p<.01). The low frequency/high frequency (LF/HF) ratio, as an index for the sympathovagal balance, was elevated by exercise and remained at a similarly high level at 10 min post-exercise (p<.01). The muscle properties of rectus femoris were changed as follows: Muscle tone and stiffness were significantly increased between pre-exercise and immediately post-exercise (p<.001), and between pre-exercise and at 10 min post-exercise (p<.001). Whereas, the elasticity showed no significant change. Conclusion : These results demonstrated that transient isokinetic exercise could induce changes in cardiac autonomic control and muscle properties. In particular, up-regulation of LF/HF ratio after exercise signifies thus enhanced sympathetic modulation by isokinetic exercise. Therefore, it is needed to understand the cardiovascular risks that may arise during isokinetic exercise for providing the basic evidence to establish appropriate isokinetic exercise protocols as effective rehabilitation exercises.

• 대한가정학회지
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• 제39권5호
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• pp.39-47
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• 2001

The purpose of this study was to investigate two different kinds of t-shirts on thermal responses at air temperature of $23{\pm}2^{\circ}C$, relative humidity of $70{\pm}5%$ and wind velocity not more than 0.5 m/sec. Five healthy men wearing boxy type t-shirts or fitted type t-shirts, participated as the subjects. Rectal temperature, skin temperatures, heart rate, clothing microclimate and subjective sensation were measured every 2 minute during experiment(rest, walking, recovery each 20 min.) and compared between two experimental garments(boxy type and fitted type t-shirts). Rectal temperature was lower in recovery phase at wearing fitted type t-shirts. Chest skin temperature was higher at wearing fitted type t-shirts and thigh and leg skin temperature were higher at wearing boxy type t-shirts.

• 대한약리학회지
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• 제18권2호
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• pp.89-102
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• 1982

The $Na^+-and\;K^+-induced\;Ca^{++}$ release was measured isotopically by millipore filter technique in pig heart mitochondria. With EGTA-quenching technique, the characteristics of mitochondrial $Ca^{++}-pool$ and the sources of $Ca^{++}$ released from mitochondria by $Na^+\;or\;K^+$ were analyzed. The mitochondrial $Ca^{++}-pool$ could be distinctly divided into two components: internal and external ones which were represented either by uptake through inner membrane, or by energy independent passive binding to external surface of mitochondria, respectively. In energized mitochondria, a large portion of $Ca^{++}$was transported into internal pool with little external binding, while in de-enerigzed state, a large portion of transported $Ca^{++}$ existed in the external pool with limited amount of $Ca^{++}$ in the internal pool which was possibly transported through the $Ca^{++}-carrier$ present in the inner membrane. $Na^+$ induced the $Ca^{++}$ release from both internal pool and external pool and external binding pool of mitochondria. In contrast, $K^+$ did not affect $Ca^{++}$ of the internal pool, but, displaced $Ca^{++}$ bound to external surface of the mitochondria. When the $Ca^{++}-reuptake$ was blocked by EGTA, the $Ca^{++}$ release from the internal pool by $Na^+$ was rapid; the rate of $Ca^{++}-efflux$ appeared to be a function of $[Na^+]^2$ and about 8mM $Na^+$ was required to elicit half-maximal velocity of $Ca^{++}-efflux$. So it was revealed that $Ca^{++}-efflux$ velocity was particulary sensitive to small changes of the $Na^+$ concentration in physiological range. Energy independent $Ca^{++}-binding$ sites of mitochondrial external surface showed unique characteristics. The total number of external $Ca^{++}-binding$ sites of pig heart mitochondria was 29 nmoles per mg protein and the dissociation constant(Kd) was $34{\mu}M$. The $Ca^{++}-binding$ to the external sites seemed to be competitively inhibited by $Na^+\;and\;K^+$; the inhibition constant(Ki) were 9.7 mM and 7.1 mM respectively. Considering the intracellular ion concentrations and large proportion of $Ca^{++}$ uptake in energized mitochondria, the external $Ca^{++}-binding$ pool of the mitochondria did not seem to play a significant role on the regulation of intracellular free $Ca^{++}$ concentration. From this experiment, it was suggested that a small change of intracellular free $Na^+$ concentration might play a role on regulation of free $Ca^{++}$ concentration in cardiac cell by influencing $Ca^{++}-efflux$ from the internal pool of mitochondria.

• Clinical and Experimental Pediatrics
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• 제48권8호
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• pp.846-856
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• 2005

목 적 : 최근 심장 기능 평가에 많이 사용되는 TDI 지표들에 대해서 우리나라의 정상 소아에 대한 연구가 아직 미흡한 실정이다. 이에 정상 소아 72례(남아 : 42례, 여아 : 30례)를 대상으로 한 TDI 및 31례를 대상으로 한 M-형 심초음파 검사를 이용한 지표들에 대한 계측치를 확인하고, 이러한 계측치에 여러 변수들(몸무게, 심박동수, 측정한 위치 등)이 미치는 영향에 대해서 관찰하였다. 방 법 : 선천성 심질환이나 심장에 영향을 미칠 수 있는 질환이 없는 건강한 소아를 대상으로 하여, 심첨 4방도, 심첨 2방도의 여러 부위에서 PW-TDI를 이용하여 최대 심근 속도를 측정하고, 측정 부위에 따른 계측치의 차이, 나이, 몸무게 및 심박동수 등이 이러한 측정치들에 미치는 영향에 대해서 연구하였다. 또한 심첨 4방도에서 각각의 판막륜 방향으로 M-형 심초음파 검사를 시행하여 나이, 몸무게 및 심박동수와 연관 관계가 있는지 알아보았다. 또한 M-형 심초음파 검사에서 측정한 값들과 TDI 계측치들과의 관계에 대해서도 연구하였다. 결 과 : TDI로 측정한 여러 변수들은 남녀, 심초음파 기기간 및 검사를 시행한 의사간에는 의미있는 차이를 보이지 않았다. 판막륜과 판막륜 및 심첨의 중간 부위에서 측정한 값간에는 판막륜에서 측정한 값들이 의미있게 높게 측정되었으며, 우심실 측벽의 측정치가 심실 중격 및 좌심실 부위에서 측정한 값보다 높았다. 심근 단축률과 TDI 측정치간에는 상관 관계를 보이지 않았다. 심박동수와의 상관 관계를 보면 S-및 E-파형의 경우 심박동수와 상관 관계가 없었으나, A-파형 및 A/E 비는 심박동수와 양의 상관 관계를 보였다. 몸무게와의 상관 관계도 측정한 부위 및 계측치 들마다 일정한 상관 관계를 보여 주지는 못하였다. M-형 심초음파 검사로 측정한 판막륜의 움직임은 성별간에 유의한 차이를 보이지 않았으며, ALD는 몸무게와 양의 상관 관계를, 이동률은 음의 상관 관계를 보이는 경향이 있었다. 그러나 이동률과 TDI 계측치들 간에는 유의한 상관 관계를 발견할 수 없었다. 결 론 : 정상 소아들에서 TDI를 이용하여 최대 심근 속도를 측정하고, 또한 M-형 심초음파 검사를 이용한 판막륜의 움직임을 관찰해 보았다. 이러한 계측치들을 토대로 좀더 많은 례를 통한 한국 소아들의 TDI 및 M-형 심초음파 검사를 이용한 판막륜의 움직임에 대한 정상치를 확립하여야 하겠으며, 선천성 및 후천성 심질환을 가진 환아들에서의 임상 적용을 기대해 본다.

• 한국전문물리치료학회지
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• 제12권4호
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• pp.26-32
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• 2005

This study was purposed to provide basic information on the correct application of a wheelchair's backrest angle by investigating the change in cardiopulmonary function according to backrest angle during propulsion. This study examined the effects of the wheelchair's backrest angle on the cardiopulmonary function by varying the angle to $0^{\circ}$, $10^{\circ}$ and $20^{\circ}$ with a propulsion velocity of 60 m/min. The experimental parameters were respiration rate, oxygen consumption rate and oxygen consumption rate/kg which were measured by a portable wireless oxygen consumption meter (COSMED, $K4b^2$). The results of the study were as follows: 1) There were no statistically significant differences in respiration rates due to changes in the wheelchair backrest angle (p>.05). 2) There were statistically significant differences in oxygen consumption rates due to changes in the wheelchair backrest angle (p<.05). 3) There were also statistically significant differences in the oxygen consumption rate/kg due to changes in the wheelchair backrest angle (p<.05). In conclusion, changes in the backrest angle of wheelchairs during propulsion influences oxygen consumption rates and heart rates, while respiration rates are not affected. Therefore, a training program for good seating and posture needs to be provided, and the wheelchair seating system should be equipped with the unadjustable-angle wheelchair to reduce the functional load on the cardiopulmonary system.