• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년 학술대회 논문집 정보 및 제어부문
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• pp.232-234
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• 2006

Diabetic neuropathy is one of the most common diabetic complications. In clinical practices, nerve conduction velocity (NCV) has been used as a standard method for diagnosing diabetic neuropathy. However, it applies maximum of 100mA electric stimulus to nerves causing stress and pain to patients. In this study. as a non-invasive method, $TcpO_2$ was utilized to investigate the difference and relationship between $TcpO_2$ and $SpO_2$ of normal and diabetic neuropathy subjects. In addition, a new method of diagnosing diabetic neuropathy using $TcpO_2$ is suggested. 50 normal subjects and 50 diabetic patients with neuropathy diagnosed by NCV participated in this study. Parameters used in this study were $TcpO_2,\;TcpCo_2$, and $SpO_2$. As a result of the $TcpO_2$ measurements, statistical significances were found from $TcpO_2$ of hands and feet from normal and patients group (p<0.01). $SpO_2$ measured from index finger of normal and patient groups showed no statistical significance (p>0.05). On the other hand, $SpO_2$ measured from great toes of normal and patient group showed statistical significance (p<0.01). Correlation coefficient between $SpO_2$ of finger and $TcpO_2$ of hand was 0.400 (p<0.01) and $SpO_2$ of toe and $TcpO_2$ of foot was 0.471 (p<0.01). Both correlation values were statistically significant. Sensitivities and specificities of the $TcpO_2$ method were found to be 66 % and 92 %, respectively. If suggested $TcpO_2$ method is used periodically. prevention and early diagnosis of diabetic neuropathy is possible.

• 전자공학회논문지SC
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• 제44권3호
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• pp.1-8
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• 2007

당뇨병성 신경병증은 당뇨병성 신증, 당뇨병성 망막병증과 함께 당뇨병의 가장 흔한 합병증 중의 하나로 임상에서는 신경전도검사(nerve conduction velocity: NCV)를 실시하여 신경병증의 유무를 진단한다. 그러나 신경전도검사는 피부에 직접적으로 최대 100mA의 전기자극을 가하므로 피검자가 놀라거나 고통을 호소하는 경우가 많다. 본 논문에서는 $TcpO_2$를 이용하여 비관혈적으로 신경병증이 있는 그룹과 정상인 그룹 간의 $TcpO_2$와 $SpO_2$의 차이를 확인하고, $TcpO_2$와 $SpO_2$가 어떠한 관계인지 살펴보았다. 또한 $TcpO_2$ 측정방법을 당뇨병성 신경병증의 새로운 조기 진단 방법으로 제안하고자 하였다. 실험은 정상인 50명과 NCV를 통해 신경병증으로 확진 받은 당뇨병 환자 50명을 대상으로 하였으며, 분석 파라미터는 $TcpO_2$, $TcpCO_2$, $SpO_2$이었다. 측정결과 $TcpO_2$는 정상인과 당뇨병성 신경병증 환자 그룹 간에 손과 발에서 모두 통계적으로 유의한 차이가 있었다(p<0.01). $SpO_2$는 검지에서는 정상인과 당뇨병성 신경병증 환자 간에 통계적으로 차이가 없었지만(p>0.05), 엄지발가락에서는 유의한 차이가 있었다(p<0.01). 손가락의 $SpO_2$와 손의 $TcpO_2$는 상관관계가 0.400(p<0.01), 발가락의 $SpO_2$와 발의 $TcpO_2$는 0.471(p<0.01)로 통계적으로 유의한 상관관계를 발견하였다. 정상인과 당뇨병성 신경병증 환자 그룹 간에 손과 발의 $TcpO_2$ 방법의 민감도는 66%, 특이도는 92%로 나타났다. 본 연구를 통해서 $TcpO_2$ 방법이 신경병증의 유무를 확인할 수 있는 사전검사 도구로 사용이 가능할 수 있으며, 주기적인 $TcpO_2$ 검사를 통해 혈관폐색과 신경병증을 조기에 발견할 수 있어 당뇨병으로 인한 혈관폐색과 신경병증을 조기에 진단 할 수 있는 유용한 방법이 될 것으로 사료된다.

• 한국진공학회지
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• 제19권3호
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• pp.230-235
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• 2010

본 논문에서는 TCP-CVD를 이용하여 실리콘 산화막 형성에서 산화막의 특성에 영향을 미치는 전력, 가스 유량, 기판 바이어스 등의 공정조건에 따른 증착률과 굴절률을 제어하고자 한다. 그 결과 기판온도 300 [$^{\circ}C$], $SiH_4$ : $O_2$=50 : 100 [sccm], TCP power 1 [kW], 기판 바이어스 200 [W]를 인가한 조건에서 매우 우수한 균일도(<1 [%]) 및 증착률(0.28 [${\mu}m$/min])과 굴절률 (1.4610-1.4621)을 나타내는 안정된 $SiO_2$ 산화박막을 제조할 수 있었다.

• 한국재료학회지
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• 제28권3호
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• pp.142-147
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• 2018

${\beta}-Tricalcium$ phosphate (TCP) was added to $Al_2O_3$ to make a biomaterial with good mechanical properties. Using a TCP powder synthesized by a polymer complexation method, $Al_2O_3$ composites containing 30 wt% TCP were fabricated and characterized for densification, phase, microstructure, strength, and fracture toughness. With optimizing the powder preparation conditions, a high densification of 97 % was obtained by sintering at $1350^{\circ}C$ for 2 h. No reaction between the two components occurred and there was no transition to ${\alpha}-TCP$. TCP grains with a size of $2-4{\mu}m$ were well surrounded by $Al_2O_3$ grains with a size of $1{\mu}m$ or less. Strength 61(Brazilian) or 187(3-p MOR) MPa, and fracture toughness 1.7 (notched beam) or 2.5 (indentation) $MPa{\cdot}m^{1/2}$ were obtained, which are large improvements over the strength of $TCP/Al_2O_3$ composites and toughness of TCP and hydroxyapatite in previous studies.

• 한국세라믹학회지
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• 제41권3호
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• pp.202-209
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• 2004

침전법 및 솔젤법에 의하여 10- l5 nm 및 500 nm 크기의 구형 TiO$_2$ 분말을 제조하고 수열합성법으로 50-70 nm 및 120-250 nm 크기의 침상 hydroxyapatite(이하 HA라 표기) 입자를 각각 제조한 다음, 두 분말의 조성비를 달리한 세 종류(HA/TiO$_2$비; 75/25, 50/50, 25/75wt%)의 HA/TiO$_2$ 복합분말을 planetary 볼밀로 혼합하여 각각 제조하였다. 복합분말을 탄소몰드에 넣고 hot-press를 사용하여 가압소결로 치밀체를 제조하였는데, 가압도중 대부분의 HA가 tricalcium phosphate(이하 TCP라 표기)로 분해되면서 $\beta$-TCP/TiO$_2$ 복합체가 제조되었다. 제조된 복합체의 미세구조와 소결밀도는 복합분말의 형태와 조성에 따라 변화하였는데, 입자가 균질하게 분산되어 있는 미세구조를 갖는 복합분말을 소결한 경우, 치밀한 소결체를 얻을 수 있었으며, 소결온도가 증가할수록 균질한 미세구조를 나타내었다. 또한 복합분말 내 HA 함량이 증가하면서 소결체의 입자크기가 증가한 반면, 소결밀도가 감소하고, 미세구조는 불균질하였다. 반대로 HA분말에 비하여 TiO$_2$분말의 함량이 큰 시편은 전체적으로 작은 입자크기와 균질한 미세구조를 나타냈으며, 소결밀도 또한 증가하였다.

• 한국재료학회지
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• 제17권9호
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• pp.480-483
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• 2007

Hydroxyapatites were prepared by the different $SiO_2$ addition at $1450^{\circ}C$ for 2h. With the increase of $SiO_2$ addition, microstructure, bulk density, porosity, mechanical strength of $hydroxyapatite/{\beta}-TCP$ composite were investigated. When the sintered HAp contained 1 wt% $SiO_2$, the each properties of the HAp were increased. But the excess addition of $SiO_2$ content above 1wt% the each property were decreased. This results were due to the ${\beta}-TCP$ phase. The ${\beta}-TCP$ phase appeared at 3 wt% $SiO_2$ addition and the ${\beta}-TCP$ phase was enhanced by the $SiO_2$ increasing.

• 한국세라믹학회지
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• 제52권5호
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• pp.374-379
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• 2015

Mullite-matrix and $Al_2O_3$-matrix composites were fabricated with 30 wt% hydroxyapatite (HA) and tricalcium phosphate (TCP), respectively, as additives to give bioactivity. A diphasic gel process was employed to lower the densification temperature of the mullite matrix to $1320^{\circ}C$. A polymer complexation process was used to synthesize a TCP powder that was fully densified at $1250^{\circ}C$, for application to the matrix. For the HA/mullite composite, HA decomposed during sintering by reactions with the matrix components of $Al_2O_3$ and $SiO_2$, resulting in a mixture of $Al_2O_3$, TCP, and other minor phases with a low densification of less than 88% of the theoretical density (TD). In contrast, the TCP/$Al_2O_3$ composite was highly densified by sintering at $1350^{\circ}C$ to 96%TD with no reaction between the components. Different from the TCP monolith, the TCP/$Al_2O_3$ composite also showed a fine microstructure and intergranular fracture, both of which characteristics are advantageous for strength and fracture toughness.

• 한국재료학회지
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• 제29권2호
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• pp.129-135
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• 2019

A powder mixture of 70 wt% $Al_2O_3$ and 30 wt% hydroxyapatite (HA) is sintered at $1300^{\circ}C$ or $1350^{\circ}C$ for 2 h at normal pressure. An $MgF_2$-added composition to make HA into fluorapatite (FA) is also prepared for comparison. The samples without $MgF_2$ show ${\alpha}$ & ${\beta}$-tricalcium phosphates (TCPs) and $Al_2O_3$ phases with no HA at either of the sintering temperatures. In the case of $1,350^{\circ}C$, a $CaAl_4O_7$ phase is also found. Densification values are 69 and 78 %, and strengths are 156 and 104 MPa for 1,300 and $1,350^{\circ}C$, respectively. Because the decomposition of HA produces a $H_2O$ vapor, fewer large pores of $5-6{\mu}m$ form at $1,300^{\circ}C$. The $MgF_2$-added samples show FA and $Al_2O_3$ phases with no TCP. Densification values are 79 and 87 %, and strengths are 104 and 143 MPa for 1,300 and $1,350^{\circ}C$, respectively. No large pores are observed, and the grain size of FA ($1-2{\mu}m$) is bigger than that of TCP ($0.7{\mu}m{\geq}$) in the samples without $MgF_2$. The resulting $TCP/Al_2O_3$ and $FA/Al_2O_3$ composites fabricated in situ exhibit strengths 6-10 times higher than monolithic TCP and HA.

• 한국세라믹학회지
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• 제30권11호
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• pp.905-910
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• 1993

$\alpha$-tricalcium phosphate($\alpha$-TCP) powders were synthesized and their hydration properties were investigated in Tris. solution. Two kinds of $\alpha$-TCP powder samples were prepared; the one is reaction product of CaHPO4.2H2O and CaCO3, and another is that of hydroxyapatite(HAp) and $\beta$-Ca2P2O7. They were satisfied with Ca/P mole ratio 1.5 and were heated at 150$0^{\circ}C$ for 5 hours. In the hydration of $\alpha$-TCP samples the powder which was synthesized from HAp and $\beta$-Ca2P2O7 was hydrated faster than that from CaHPO4.2H2O and CaCO3. The hydration reaction of $\alpha$-TCP powder transformed rapidly into HAp accompanying setting and hardening. It was realized that the hydration reaction of $\alpha$-TCP was due to the solution-precipitation mechanism and the hydrates from the reaction were Ca-deficient HAp having funtional group HPO42-.

• Archives of Plastic Surgery
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• 제37권5호
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• pp.547-554
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• 2010

Purpose: The purpose of this study is to delineate the optimal time of venous revascularization for preventing the flap necrosis due to venous occlusion, and to clarify the usefulness of tissue oxygen pressure ($TcpO_2$) in the determination of the point of time for venous revascularization. Methods: Thirty-six, $3{\times}3\;cm$ sized epigastric island flap was elevated in left abdomen of male Sprague-Dawley rat weighing 250 gram. Flaps were randomly assigned to six groups of six flaps according to the duration of venous occlusion with microvascular clamp; 10 minutes in the group I as the control, 60 minutes in the group II, 2 hours in the group III, 3 hours in the group IV, 4 hours in the group V, and 6 hours in the group VI, respectively. Just before removal of clamp after flap was reposed in situ, the ratio of $TcpO_2$ (tissue oxygen pressure) of the island flap to that of right abdomen was calculated in each group, and tissue specimen was harvested from the distal area of the flap for histological evaluation of vascular change. Five days later, survival area of the flap was estimated, and evaluated the correlation between the tissue oxygen pressure and the rate of flap survival. Results: The $TcpO_2$ and the survival rate of flap were decreased proportionally with the duration of venous occlusion. The ratio of the $TcpO_2$ of the flap is decreased abruptly to below sixty percentile compared to the $TcpO_2$ of normal tissue, and the survived area of the flap is decreased to nine-tenth of the designed size after three hours of total venous occlusion. Histologically, the number of congested vessels was increased according to venous occluded time, and proportionally increased after 3-hours of occlusion significantly. Conclusion: There is a close correlation between the $TcpO_2$ and the survival rate of flaps according to the duration of venous occlusion. Therefore, the $TcpO_2$ represents the hemodynamic changes within the flap, and thought to be an alternative effective tool in the flap monitoring for venous revascularization.