Bi-factor MIRT True-Score Equating for Testlet-Based Tests

이규민(Gue min Lee),Won Chan Lee,Michael J Kolen,박인용(In Yong Park),Dong In Kim,Ji Seung Yang 한국교육평가학회 2015 교육평가연구 Vol.28 No.2

Lee and Lee (2014) proposed bi-factor multidimensional item response theory model (BFM) "observed-score" equating procedures. The main purposes of this study were to develop BFM "true-score" equating procedures, and to investigate applicability of the proposed procedures with actual data. Eight equating methods (including both true- and observed-score) based on dichotomous IRT (2-parameter logistic model: 2PL), polytomous IRT (graded response model: GRM), testlet response model (TRM), and BFM were compared with target equipercentile equating. Data for this study were from the Reading Comprehension test for a large-scale state assessment program, which consisted of several passages and corresponding groups of items. True- and observed-score equating methods based upon 2PL and BFM produced similar equating results. The GRM true- and observed-score equating methods provided equating results somewhat different from others, and more similar to the target equipercentile equating. Lee와 Lee(2014) 연구는 혼합형 검사에서의 bi-factor 다차원 문항반응모형을 적용한 IRT "관찰점수" 동등화 절차를 제안하였다. 이 연구는 Lee와 Lee(2014) 연구의 추수연구로 단위검사를 대상으로 bi-factor 다차원 문항반응모형을 적용한 IRT "진점수" 동등화 절차를 제안하고, 그 적용 가능성을 실제 자료를 이용하여 탐색하고자 하였다. 이를 위해 단위검사로 구성된 대규모 독해 검사 자료를 이용하여, 2모수 로지스틱 모형(2-parameter logistic model: 2PL), 등급반응모형(graded response model: GRM), 단위검사모형(testlet response model: TRM), bi-factor 모형(bi-factor model: BFM)을 적용하였으며, 관찰점수 및 진점수 동등화를 시행하여 총 8개의 동등화 방법을 적용하고, 산출된 결과를 동백분위 동등화 결과와 비교하였다. 연구 결과, 2PL과 BFM을 적용한 관찰점수 및 진점수 동등화는 유사한 결과를 산출하였으며, GRM을 적용한 관찰점수 및 진점수 동등화 방법은 다른 방법들과 다소 차이를 보이는 결과를 산출하였고, 비교 기준이 된 동백분위 동등화 결과와 보다 유사한 결과를 보였다.

쿠싱증후군 환자에서 당 대사 이상 정도에 따른 인슐린 감수성과 인슐린 저항성의 변화

정인경,김성훈,정재훈,민용기,이명식,이문규,유형준,안규정,노정현,김동준,김광원 대한내분비학회 2003 Endocrinology and metabolism Vol.18 No.4

연구배경 당질 코르티코이드는 당 대사에 매우 중요한 호르몬으로 내인성 당질 코르티코이드 과다상태인 쿠싱증후군에서는 말초조직에서 인슐린 저항이 증가하고 이를 보상하고자 인슐린 분비의 증가로 고인슐린혈증이 동반된다고 보고되고 있다. 하지만 생체 내에서와 달리 시험관내에서는 췌도세포에 당질 코르티코이드를 장시간 처리하면, 인슐린 분비 및 생합성이직접적으로 억제됨이 확인된 바 있어 쿠싱증후군 환자에서 당뇨병의 원인으로는 아마도 말초조직에서 증가된 인슐린 저항성 뿐 아니라 이를 충분히 보상하지 못하는 췌장에서의 인슐린 분비 저하가 같이 동반되어있지 않을까 하는 가설을 세우게 되었고, 아직까지 당질코르티코이드가 당대사 이상을 일으키는 기전에 대해 쿠싱증후군을 당대사 정도에 따라 인슐린 감수성과 분비능을 분석한 연구는 없었기에 이를 알아보고자 하였다. 방법: 삼성서울병원에서 쿠싱증후군으로 진단 받은 환자 15명을 대상으로 하였다. 이에 대한 대조군으로는 쿠싱증후군 환자와 같은 성별 그리고 체질량지수를 갖은 15명의 건강한 성인을 대상으로 비교 하였다 쿠싱증후군 환자를 대상으로 경구당부하 검사를 통해 당대사 정도를 정상군, 내당능장애군, 그리고 당뇨병군으로 나눈 후 정맥 당부하 검사를 시행하여 각군의 인슐린 저항성과 인슐린 분비능의 지표를 비교하고, 수술 후 쿠싱증후군이 완치된 상태에서 수술 전후의 당대사 지표의 변화를 조사하였다. 결과: 1) 쿠싱증후군 환자 중 정상인은 20%, 내당능 장애는 27%, 그리고 당뇨병은 53%였다. 체질량지수, 나이, 그리고 발병 기간은 세 군간에 의미 있는 차이가 없었으나, 24시간 소변검사의 코르티솔 농도는 당뇨병군에서 의미있게 높았다. 2) 정맥당부하 검사 결과, 인슐린 감수성 지표인 Sl는쿠싱증추린」서 1.58±0.10[×10^(-4)(min^(-1)(μU/mL)^(-1)]로 정상 대조군의 3.37±0.49[×10^(-4)(min^(-1)(μU/mL)^(-1)]에 비해 의미있게 낮았으나(P=0.024), 쿠싱증후군 환자 중 NGT, IGT, DM 군간에 서로 통계적인 차이는 없었다. 3) SG는 정상 대조군과 쿠싱증후군 환자간에는 의미있는 차이가 없었고, 쿠싱 증후군에 있어서 당대사가 악화될수록 감소하는 경향을 보였으나 의미있는 차이는 없었다. 4) 인슐린 분비능의 지표인 AIRg는 정상인에 비해 전체 쿠싱증후군 환자의 경우 증가하는 경향을 보였으나 의미있는 차이는 없었다. 하지만 쿠싱증후군 환자중에서 당대사 상태에 따라 NGT군은 1299 (1297∼1310)(mu/g/min ×10^(-2))로 정상 대조군(368.9±98.6[mu/g/min ×10^(-2)]) 보다도 의미있게 높았고, DM군{202.2 (91.1~371.4) [mu/g/min ×10^(-2)}은 NGT군에 비해 의미있게 낮았다(P=0.0031). 5) 15명중 현재 완치 상태에 있는 6명에 대해 수술전과 후로 비교하였다. 수술 전 당대사 상태가 1명은정상, 1명은 내당능 장애, 그리고 4명은 당뇨병이었으나 수술 후 시행한 경구 당부하 검사상 모두 정상 당대사 상태를 보였다. 6) 수술 후 완치된 환자 6명에 있어 인슐린 감수성지표인 Sl는 수술전에 중앙값이 1.22[×10^(-4)(min^(-1)(μU/mL)^(-1)]로 대조군에 비해 의미있게 감고』어 있었으나(p.0.05), 수술후 10.95 [×10^(-4)(min^(-1)(μU/mL)^(-1)]로 정상 수준으로 회복되었고(P=0.0022), 인슐린 분비능을 나타내는 AIRg [mu/g/min ×10^(-2)] 값도 정상수준으로 회복되었다. 특히 인슐린 분비능의 회복양상은 혈당농도에 따라 판이하게 나타나서, 정상과 내당능장애 상태에 있던 2명은 수술전에 1201 [mu/g/min ×10^(-2)]로 증가되어 있던 AIRg 값이 수술 후 정상 수준으로 감소하였고, 수술 전에 당뇨병 상태에 있던 4명의 경우 245.9 [mu/g/min ×10^(-2)]로 인슐린 분비능이 감고il어 있었는데 이들은 수술 후 모두 정상 수준으로 증가되었다 (P=0.0286). 결론: 쿠싱증후군 환자에서 당대사 이상은 80%로 높은 유병률을 보였다. 모든 쿠싱증후군환자에서 인슐린 감수성은 정상인에 비해 저하되어 있어 말초조직의 인슐린 저항이 선행됨을 시사하며, 인슐린 분비능은 당대사의 정도에 따라 다르게 나타났는데, 정상 당대사군에서는 인슐린의 저항성을 극복할 만큼 정상 대조군보다 더 많은 양의 인슐린 분비를 하다가 고코르티솔혈증이 심할수록 인슐린 분비능의 감소로 당뇨병으로 진행됨을 확인할 수 있었고, 이런 인슐린 저항성과 인슐린 분비장애는 수술 후 다시 회복되는 가역적인변화를 보였다. Background: Glucocorticoid plays an important role in the control of carbohydrate metabolism. Patients with Cushing's syndrome have been reported to have an increased incidence of carbohydrate intolerance due to peripheral insulin resistance and hyperinsulinemia, although the exact incidence and nature of this disorder have remained unclear. Few results have been published about insulin resistance and insulin secretion according to the level of glucose concentration, or about the reversibility of such defects in patients with Cushing's syndrome. Methods: To assess the effect of glucocorticoid on the insulin sensitivity and insulin secretion in Cushing's syndrome, 15 patients with Cushing's syndrome were classified into 3 groups (normal glucose tolerance: NGT, impaired glucose tolerance: IGT, diabetes: DM) according to the degree of glucose tolerance based on the oral glucose tolerance test (OGTT). Insulin modified, frequently sampled, intravenous glucose tolerance test (FSIGT) was performed before and after curative surgery on these patients and on 15 healthy control subjects. Data were evaluated by non-parametric statistical analysis. Results: 1) Among the 15 patients with Cushing's syndrome, 3 (20%) were NGT, 4 (27%) IGT, and 8 (53%) DM, based on OGTT. Twenty-four hour urinary free cortisol (UFC) was significantly higher in the DM group. 2) Insulin sensitivity index (SI) of Cushing's syndrome was significantly lower than that of the control group p=0.0024), but was not significantly different among the three Cushing's syndrome groups of NGT, IGT and DM. 3) Glucose mediated glucose disposal (SG) (Ed- confirm this abbreviation; it does not seem to match the definition) of Cushing's syndrome was not significantly different from that of the control group. 4) Insulin secretion (AIRg) of Cushing's syndrome tended to be high, but it was not significantly different from that of control. However, according to the level of glucose concentration there was significant difference in AlRg among the three Cushing's syndrome groups p=0.0031); AIRg of DM was significantly lower than that of NGT. 5) After surgical treatment, parameters of insulin sensitivity and insulin secretion were normalized in 6 cured patients; 1 with NGT, 1 with IGT, and 4 with DM, preoperatively. Median SI of all 6 patients was significantly improved up to the normal range postoperatively p=0.0022). Median AIRg of these 6 patients was balanced around that of normal control postoperatively p=0.0286). Conclusion: Eighty percent of patients with Cushing's syndrome had abnormality of carbohydrate metabolism. Insulin sensitivity was significantly decreased in Cushing's syndrome. Insulin secretion was significantly higher only in the NGT and IGT groups of Cushing's syndrome. As the hypercortisolemia is exacerbated, insulin secretion is significantly decreased and causes DM, suggesting that glucocorticoid has a direct or indirect toxic effect on the pancreatic beta cell (J Kor SOC Endocrinol 18:392-403, 2003).

인간포배기 배아의 효과적인 유리화 동결법의 개발을 위한 연구

이상민,이주희,이상원,이승민,윤산현,임진호,박흠대,이성구,Lee, Sang-Min,Lee, Ju-Hee,Lee, Sang-Won,Lee, Seoung-Min,Yoon, San-Hyun,Lim, Jin-Ho,Park, Huem-Dai,Lee, Seong-Goo 대한생식의학회 2003 Clinical and Experimental Reproductive Medicine Vol.30 No.3

Objective: The purpose of this study was to evaluate the survival rate of vitrified blastocyst according to the freezing vessels, equilibration time in cryoprotectant and artificial dehydration method. Methods: Human blastocysts were vitrified after loading onto the plastic straw, open-pulled straw (OPS), electron microscopy grid (EM grid) for 1.5 min or 3 min. They also were directly plunged into LN2 within 30sec. For artificial shrinkage of blastocysts, 36 gauge fine needle was pushed at the cellular junction of the trophectoderm into the blstocoele cavity until it shrank without damage of inner cell mass. Results: The survival rate of vitrified blastocysts on plastic straw, OPS, EM grid as freezing vessels were 26.7, 13.0 and 60.5%, respectively. The survival rate of EM grid was significantly higher than that of plastic straw and OPS (p<0.05). For 1.5 min equilibrium, the survival rates of early blastocyst (EB), middle blastocyst (MB) and late blastocyst (LB) were 64.4, 81.0, and 20.0% respectively. For 3 min equilibrium, the survival rates of EB, MB, and LB were 69.9, 50.0 and 57.5% respectively. The survival rates of EB and MB were significantly higher than that of LB in 1.5 min equilibrium group (p<0.05), however, the significance was not observed in 3 min equilibrium groups. In cytoplasmic shrinkage before vitrification, the survival rates of EB, MB and LB were 92.9, 100 and 75.9% respectively. The survival rate of MB was significantly higher than that of LB (p<0.05). The survival rates of vitrified blastocysts by artificial dehydration and slow-frozen blastocysts were not significantly different as 88.9 and 66.7%, respectively. Conclusion: This study showed that the vitrification of human blastocysts using EM grid and artificial dehydration is an effective method. Therefore, these methods would be an useful techniques for blastocyst cryopreservation.

가압가열 및 microwave에 의한 중력분 반죽 gliadin의 항원성 변화

곽지희(Ji-Hee Kwak),김꽃봉우리(Koth-Bong-Woo-Ri Kim),이청조(Chung-Jo Lee),김민지(Min-Ji Kim),김동현(Dong-Hyun Kim),선우찬(Chan Sunwoo),정슬아(Seul-A Jung),김현지(Hyun-Jee Kim),최정수(Jung-Su Choi),김성원(Seong-Won Kim),안동현(Dong-Hyun 한국식품과학회 2012 한국식품과학회지 Vol.44 No.1

본 연구에서는 가압가열 및 microwave 처리에 의한 중력분 반죽 추출물 내의 gliadin 단백질의 항원성 변화에 대해 살펴보았다. 중력분 반죽에 가압가열과 microwave를 단독 또는 병행으로 처리하여 ci-ELISA, SDS-PAGE 및 immunoblotting을 실시하였으며, 가압가열 처리에 의해서 anti-gliadin IgG 항체와 gliadin과의 결합력이 다소 감소한 것을 확인하였다. 특히 30 min 이상 처리시 더욱 감소한 것으로 나타났으며, SDS-PAGE와 immunoblotting 결과에서도 gliadin band의 강도가 약해지고 항체와의 반응도 나타나지 않았다. Microwave 처리의 경우, 5 min 이상 처리시 일부 gliadin 단백질의 소실이 관찰되었으나, 항원성에는 큰 변화가 없었다. 또한 가압가열 및 microwave 병행 처리에 의해 항원-항체 결합력이 더욱 감소되었으며, 특히 가압가열 50 min, microwave 10 min 처리시 약 35.0%로 감소되었다. 이상의 결과를 통해 가압가열 처리에 의해 중력분 반죽 추출물 내 gliadin의 항원성이 감소되는 것을 확인하였으며, microwave와 병행 처리하는 경우, 더욱 감소하는 것을 확인하였다. The aim of this study was to determine the optimal physical treatment to reduce the antigenicity of gliadin in wheat dough. Medium wheat dough was treated with an autoclave (5, 10, 30, and 50 min at 121℃, 1 atm), a microwave (1, 5, and 10 min) or both (10, 30, and 50 min/5, 10 min). The proteins in the dough extracts were analyzed by SDS-PAGE and the binding ability of anti-gliadin IgG to gliadin was examined by ci-ELISA and immunoblotting. Results showed that the ability of anti-gliadin IgG to bind to gliadin in wheat dough treated with an autoclave alone or in combination with a microwave was decreased. Especially, it declined to ~77% after autoclaving for 30 min and 35% after both autoclaving for 50 min and microwaving for 5 min. In addition, the intensity of gliadin bands in SDS-PAGE were weakened and anti-gliadin IgG did not recognize gliadin in immunoblotting. However, microwaving alone did not affect the antigenicity of gliadin in wheat dough. These results indicate that autoclaving may affect the reduction of the antigenicity of gliadin in medium wheat dough. Moreover, autoclaving in combination with microwaving is more effective for reducing the antigenicity of wheat dough.

주요우울증에 대한 벤라팍신의 효과 및 안전성

이민수,남종원,강성민,연병길,오병훈,이철,정인과,채정민,백인호 대한신경정신의학회 2000 신경정신의학 Vol.39 No.6

연구목적 : 주요우울증 환자에서 벤라팍신의 치료 효과와 안정성을 조사하기 위해 다기관 개방연구를 시행하였다. 방 법 : DSM-IV 진단 기준에 의거하여 주요우울증으로 진단된 환자중 벤라팍신 투여에 동의한 환자를 대상으로 하였다. 선택된 환자에서 다른 항우울제를 복용하고 있는 경우 14일 이상의 약물 배설기간을 가진후 벤라팍신을 6주간 투여하였으며, 기준점, 1주, 2주, 4주, 6주 후에 HAM-D, MADRS, 그리고 CGI등을 사용하여 평가하였다. 본 연구기간중 발생된 모든 부작용은 부작용의 발생 및 소설 시기, 심한 정도, 발생 빈도, 벤라팍신과의 관련성, 관련 조치 및 결과에 대하여 증례기록서에 기록하도록 하였다. 결 과 : 총 141명을 대상으로 하였으며, 이중 94명(66.7%)이 6주간의 연구를 완결하였고, 47명(33.3%)이 중도탈락하였다. HAM-D총점수는 벤라팍신 투여 1주후부터 유의한 감소를 나타내었으며, 2주,4주, 6주후에도 지속적인 감소를 보였다. MADRS의 총점수도벤라팍신 투여 1주 후부터 유의한 호전을 나타내었으며, 2주, 4주, 6주 후에도 지속적인 감소를 보였다. CGI에서도 기준점, 1주, 2주, 4주, 6주 후 각각의 시점 사이에 유의한 호전이 보였다. 활력징후, 일반 혈액학, 생화학, 심전도 검사 등에서 유의한 변화는 없었다. 벤라팍신과 관련된 부작용으로 흔히 보고한 증상은 오심(10.6%), 소화불량(9.5%), 변비(8.5%), 현기증(8.5%)등 이었다. 결 론 : 다기관 개방연구를 통해 주요우울증 환자에 대한 벤라팍신의 투여는 우울증상의 호전에 효과적이었으며 안전하였다. Objective : A Multicenter open-label study was conducted to evaluate the clinical efficacy and safety of venlafaxine for the tretment in patients with major depression. Method : The study was done in patients with major depression diagnosed by DSM-IV who accepted venlafaxine medication. In cases of the patients taking other antidepressants, 6 weeks of venlafaxine medication was carried out after 14 days of drug excretion period and evaluation using HAM-D, MADRS, and CGI was done at baseline, and after 1, 2, 4, and 6 weeks. Regarding all side effects that had occurred during the period of our study such as their developed/disappeared time, severities, incidences, relationship with venlafaxine, managements and results have been putted into the records. Results : A total of 141 patients were enrolled. Among 94 of them finished the 6 weeks of research and 41 of them did not make it through the research. Total HAM-D scores showed significant decrease after 1 week of venlafzxine medication and continous decrease through the study period. Total scores of MADRS also showed significant improvement after 1 week and continuous decrease through the study period. Similarly, CGI showed significant improvement between baseline, 1, 2, 4, and 6 weeks. There were no significant changes in vital sign, CBC, chemistry, and EKG. The commonly reported side effects of venlafaxine were nausea(10.6%), indigestion(9.5%), constipation(8.5%), and dizziness(8.5%). Conclusion : According to the results, venlafaxine was effective and safe in the treatment of patients with major depression.

Active Balancing of Li-Ion Battery Cells Using Transformer as Energy Carrier

Lee, Kyung-Min,Lee, Sang-Won,Choi, Yoon-Geol,Kang, Bongkoo Institute of Electrical and Electronics Engineers 2017 IEEE transactions on industrial electronics Vol.64 No.2

<P>A circuit for balancing Li-ion battery cells is proposed. This circuit requires one small transformer and N + 3 bilateral switches to equalize the charging states of N serially connected battery cells. The transformer works as an energy carrier, and the switches select two unbalanced cells that require an energy transfer from one to the other cell. The circuit was tested for a 12-cell Li-ion battery under static, cyclic, and dynamic charging/discharging conditions. Under static condition, the power-transfer efficiency was measured as 80.4% at a balancing power of 0.78W; two 4400-mA . h battery cells at a state of charge (SOC) = 70 and 80% were equalized after 78 min. The results of cyclic and dynamic charging/discharging conditions show that the circuit is appropriate for balancing the Li-ion battery cells for vehicles and energy storage systems.</P>

비복신경이식을 이용한 긴 거리의 말초신경 결손부 수복

이종호,이세영,김명진,이은진,안강민,김성민,최원재,명훈,황순정,서병무,최진영,정필훈 大韓顎顔面成形再建外科學會 2003 Maxillofacial Plastic Reconstructive Surgery Vol.25 No.2

The surgery of oral and maxillofacial area poses the risk of cranial nerve damage such as trigeminal nerve or facial nerve. Inferior alveolar nerve is prone to damage in the third molar extraction, implant installation, orthognathic surgery, open reduction and rigid fixation, and tumor ablation surgery. On the other hands,facial nerve is likely to be damaged or sacrificed with trauma or parotidectomy. In case of inferior alveolar nerve injury, the incidence is reported to be about 1.3%. The nerve function will almost recover in minimal damage, but it won't recover at last in total damage of a part of nerve unit. In latter cases, nerve regeneration in intended by allograft as nerve substitute or various route of merve condit. But the recovery with autograft is believed to be most relialbe mrthod in the rapair of long-span(longer than 15㎜)nerve defect. We have performed autologous sural nerve graft in the repair of nerve defect, which is caused by resection of benign or malignant tumor. Hereby we report the method of nerve harvesting, recovery of defected peripheral nerve and the complications of donor site with the discussion of sural nerve anatomy.

개의 췌도분리에서 췌장의 팽창과 콜라겐 분해요소

이상훈,김성주,박정환,김종성,오승훈,한진수,정인경,양태영,김동준,김광원,이문규,민용기,이명식,정재훈,함종렬 대한당뇨병학회 2000 Diabetes and Metabolism Journal Vol.24 No.2

Backgrounds: One of the main problems conditioning the outcome of islet transplantation is the ability to separate a sufficient number of viable islets with preserved function. Islet purification is critically affected by all of the isolation stages. Thus, it is necessary to set up the standard isolation method that islets are separate well from acinar without compromising islet yield and viability. Methods: Twenty three adult mongrel dogs were used for the experiment of total pancreatectomy with islet isolation. The islets were properly isolated by a modified Recordi method. The obtained islets were further purified by centrifugation on discontinuous gradients using cell separation system (Model 2991, Cobe, Lakewood Colo). We evaluated islet number (islet equivalent number, 150 um equivalents/kg of recipient body weight, IEq/kg), purity, cell volume, viabilty, recovery rate, and comparison of outcome according to the isolation conditions. Results: 1) The mean of islet numbers before purification were 13543±9431Eq/kg, digestion times were 13.8±2.6 min., digestion temperature was 37.4±0.2℃, purity was 59.7?.0%, viability was 90.0±2.1%, cell volume was 4.7±1.1 mL, islet number after purification were 4064±361 IEq/kg, and recovery rate was 29±2.9%. 2) Isolated islet numbers were different according to the degree of pancreas distension with collagenase, digestion temperature, and digestion time. 3) The best conditions for islet isolation were above 37.5℃ in temperature at recirculation of collagenase, within 12 min in digestion time and well distended pancreas with collagenase. 4) According to multiple regression adjusted by variable factors, the degree of pancreas distension with collagenase and digestion time were independently associated factors for successful islet isolation. Conclusions: In this study, we concluded that the degree of pancreas distension with collagenase and digestion time were independent factors for successful islet isolation and the best conditions for islet isolation were above 37.5℃ in temperature at recirculation of collagenase, within 12 min in digestion time and well distended pancreas with collagenase.

Characterizations of Modified Silica Nanoparticles(I)

Min, Seong-Kee,Park, Chan-Young,Lee, Won-Ki,Seul, Soo-Duk Materials Research Society of Korea 2012 한국재료학회지 Vol.22 No.6

(3-mercaptopropyl)trimethoxysilane (MPTMS) was used as a silylation agent, and modified silica nanoparticles were prepared by solution polymerization. 2.0 g of silica nanoparticles, 150 ml of toluene, and 20 ml of MPTMS were put into a 300 ml flask, and these mixtures were dispersed with ultrasonic vibration for 60 min. 0.2 g of hydroquinone as an inhibitor and 1 to 2 drops of 2,6-dimethylpyridine as a catalyst were added into the mixture. The mixture was then stirred with a magnetic stirrer for 8 hrs. at room temperature. After the reaction, the mixture was centrifuged for 1 hr. at 6000rpm. After precipitation, 150 ml of ethanol was added, and ultrasonic vibration was applied for 30 min. After the ultrasonic vibration, centrifugation was carried out again for 1 hr. at 6000rpm. Organo-modification of silica nanoparticles with a ${\gamma}$-methacryloxypropyl functional group was successfully achieved by solution polymerization in the ethanol solution. The characteristics of the ${\gamma}$-mercaptopropyl modified silica nanoparticles (MPSN) were examined using X-ray photoelectron spectroscopy (XPS, THERMO VG SCIENTIFIC, MultiLab 2000), a laser scattering system (LSS, TOPCON Co., GLS-1000), Fourier transform infrared spectroscopy (FTIR, JASCO INTERNATIONL CO., FT/IR-4200), scanning electron microscopy (SEM, HITACHI, S-2400), an elemental analysis (EA, Elementar, Vario macro/micro) and a thermogravimetric analysis (TGA, Perkin Elmer, TGA 7, Pyris 1). From the analysis results, the content of the methacryloxypropyl group was 0.98 mmol/g and the conversion rate of acrylamide monomer was 93%. SEM analysis results showed that the organo-modification of ultra-fine particles effectively prevented their agglomeration and improved their dispensability.

선인장 양심실 보조장치의 설계 및 임상적용을 위한 평가

민병구,박찬영,최재순,이혁수,황창모,김삼성,윤걸중,김종원,선경,이경갑,정종태,김원곤 제주대학교 인공심장이식연구소 2001 인공심장 연구 Vol.2 No.1

현재 개발되고 있는 맥동형 이식형 인공심장은 완전이식형 인공심장과 좌심실보조장치 뿐이다. 좌심실보조장치를 장착한 환자의 10~15%가 우심실의 보조를 필요로하고 완전이식형 인공심장의 장착을 위해서는 자연심장을 제거해야하는 상황에서 이식형 양심실보조장치에 대한 필요성이 대두되고 있다. 본 연구진은 완전이식형 인공심장으로 개발된 한국형 인공심장을 개선하여 양심 실 보조장치를 개발하였다. 양심실보조장치는 이동형 작동기식 미케니즘을 이용하고 있으며 에너지 변환장치와 감속기로 구성된 작동기와 혈액주머니, 그리고 내장형 제어기로 구성되어 있다. 선인장 펌프로 명명된 KAH350은 캐뉼라의 연결을 위한 커넥터를 포함하여 길이 177mm, 폭 164mm, 높이 67 이고 무게 780g이며 최대 심박출량은 5L/min 이다. 양심실보조장치로 개발된 선인장펌프는 좌심실보조장치로도 응용이 가능하다. 이식적합성과 생체적합성을 평가하기 위하여 좌심실보조장치로 5회, 양싱실보조장치로 6회의 동물실험을 수행하였다. 각각 최장 28일간 생존하였으며 11회의 동물실험중 장치의 결함에 의한 것이 3회 있었는데 이들은 모두 전자장치의 결함과 방수처리문제였다. 현재 이식적합성과 일박출량을 향상시킨 KAH400모델이 개발중이다. The types of pulsatile implantable artificial hearts that are on the way of development and have been developed are totally implantable artificial heart and implantable left ventricular assist device (LVAD). Approximately 10% to 15% of all patients Implanted with wearable VADs have required right heart support with another device. And it is reluctant to patient who should remove his or her own heart to be implanted with total artificial heart. These situations drive the development of implantable bi-ventricular assist device (BVAD). The Korean BVAD was develophed by modifying the moving actuator type Korean artificial heart. This electro-mechanical BVAD comprises actuator including energy converter and reduction gear train, blood sacs, and internal motor and energy controllers. The KAH350 which is named as 'Cactus Pump' is 177mm in length, 164mm in width, and 67mm in thickness including connectors and nuts. The weight and maximum cardiac output of Cactus Pump is 780g and 5L/min, respectively. The Cactus Pump that was developed as BVAD could be used as LVAD by attaching compliance caps on the 2 ports of one ventricle. The animal experiments were undergone 5 times for LVAD, and 6 times for BVAD. The best records were 28 days survival in both applications. There were 3 times of device failure and they were all associated with electrical connection and hermetic sealing. The KAH400 that has improved anatomical fitting characterisitcs and stroke volume is on development.