• E2M - 전기 전자와 첨단 소재
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• 제9권1호
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• pp.24-29
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• 1996

A composite piezoelectric ceramic transducer is fabricated with three piezoelectric ceramic disk vibrators and two sheets of thin insulator. Its equivalent circuit is derived from the Mason's model of a thickness-driven piezoelectric vibrator. When the electric input near its fundamental resonance frequency is applied to the center vibrator and the output voltages across the left and the right vibrators are connected in series to the resistor loads, the load characteristics at resonance frequencies under the various resistor loads and the frequency characteristics near the resonance frequency without load are investigated. Furthermore, symbolic expressions for input impedances, voltage ratios, resonance frequencies, and bandwidths are derived. The data calculated from those symbolic expressions are agreed well with the measurement data.

• Steel and Composite Structures
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• 제31권3호
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• pp.277-290
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• 2019

This paper investigates the parametric instability (PI) of multilayered composite conical shells (MLCCSs) under axial load periodically varying the time, using the first order shear deformation theory (FOSDT). The basic equations for the MLCCSs are derived and then the Galerkin method is used to obtain the ordinary differential equation of the motion. The equation of motion converted to the Mathieu-Hill type differential equation, in which the DI is examined employing the Bolotin's method. The expressions for left and right limits of dimensionless parametric instability regions (PIRs) of MLCCSs based on the FOSDT are obtained. Finally, the influence of various parameters; lay-up, shear deformations (SDs), aspect ratio, as well as loading factors on the borders of the PIRs are examined.

• Journal of Chest Surgery
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• 제21권6호
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• pp.970-978
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• 1988

There is tendency of increasing number and decreasing age of patients who are indicated for Rastelli operation for their cyanotic congenital heart disease. So there is the need to find the criterion which saves the patients from early postoperative hemodynamic disturbances. We reviewed the 26 patients who had been performed Rastelli operation at Seoul national University Hospital from January 1981 to June 1988. mean age of the patients was 7.8*3.4 years[range 2.5-15years], mean body surface area[BSA] 0.79*0.25m2[range 0.49-1.51m2] and mean hematocrit 57.95*12%[range 48-80%]. We divided these patients into survived group and died group before postoperative 72 hours, and analyzed preoperative arterial oxygen saturation[SaO2], the ratio of diameter of right pulmonary artery to ascending aorta[RPA/AA], the ratio of both right and left pulmonary artery diameter to descending thoracic aorta[RPA+LPA/DTA], pulmonary artery index[PA index], cardiopulmonary bypass time, aorta cross-clamping time, postoperative perfusion state and total amount of dopamine infused postoperatively. The results showed that RPA+LPA/DTA and PA index were statistically significant factors to influence early postoperative cardiac death rate[P< 0.05]. Especially there were good linear correlations between PA index[X] and peripheral perfusion index[Y][Y= - 1.15+0.02 X, r=0.86, P<0.01]and between PA index[X] and total amount of dopamine infused before postoperative 72 hours[mg/kg, Y][Y=61.94 - 0.15 X, r=-0.80, P < 0.01]. Also there were tendencies that the higher RPA+LPA/DTA[Y], the better peripheral perfusion [X] and the lower need of dopamine[X], but no statistical significance.[Y=0.78+1.60 X, r =0. 49, P >0.05] And the discriminate analysis showed that patients with PA index over 221 mm2/BSA could undergo correction with 25 per cent of error rate. In conclusion, early postoperative hemodynamic states could be predicted by preoperatively measured PA index, and which can be used as a criterion for Rastelli operation performed on cyanotic congenital heart disease.

• Journal of Yeungnam Medical Science
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• 제7권2호
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• pp.141-149
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• 1990

The authors conducted a clinical observation of 55 cases of solitary pulmonary nodules at Yeungnam University Hospital from June 1986 to October 1990, and the following results were obtained : 1. The age distribution was ranged from 18 to 77 years, and the male-to-female ratio was 1.8:1. 2. Among 55 cases of nodules, 28 cases were benign and 27 cases were malignant nodules, and of malignant nodules, the primary lung cancer was 23 cases and of benign nodules, 18 cases were tuberculoma. 3. 23 cases (41.8%) was asymptomatic and the other 32 cases were symptomatic; chest pain 12 cases, hemoptysis; 8 cases, cough; 8 cases and dyspnea; 4 cases. 4. The non-smoker-to-smoker ratio was 1:1.04, but among 23 smoker over 20 pack years, 14 cases were malignant nodules. 5. According to nodular size, there is no striking differences between benign and malignant nodules except 3-4cm sized nodules. 6. The lobar distribution of nodules, 35 cases were in the right lung (upper lobe; 14 cases, middle lobe; 11 cases, and lower lobe; 10 cases) and 20 cases were in the left lung(upper lobe; 9 cases, lower lobe; 11 cases), and the malignant nodules were most commonly observed in the right upper lung.

• 한국자동차공학회논문집
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• 제25권2호
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• pp.242-249
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• 2017

In this study, the relationship between the shape of a passenger airbag and the possibility of injury is analyzed using the Taguchi method. The optimal shape combination is proposed for a design guideline that can reduce the possibility of injury to the dummy. The airbag FE model for analysis is obtained using a CAD system that can change the shape through several independent variables. The widths of the left / right, top / bottom, and back / forth direction of the airbag shape are set as the design factors, and the effect of the combination injury probability according to the shape is analyzed. The minimum geometric combinations are obtained using the orthogonal array method. The signal to noise ratio is calculated and the optimal shape combination is obtained through sensitivity analysis. The obtained optimal shape combination is compared with the possibility of injury of the initial airbag shape to confirm improved airbag performance.

• 대한치과의사협회지
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• 제49권4호
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• pp.211-218
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• 2011

Purpose: An impacted tooth is defined as a tooth that shows delayed eruption and is expected to erupt incompletely by clinical and radiograph examination despite it reaching its expected time of eruption. The aims of this study were to investigate the clinical and radiological characteristics and treatment duration and method of impacted teeth in Korean patients. Materials and Methods: For this study we used clinical records, study models, panoramic radiographs and intraoral photographs of patients who attended Gachon University Gil Hospital Orthodontic Department between 2005 and 2008. There were 164 patients with a total number of 202 impacted teeth. Results: Male patients shows a little more prevalence than female patients (1.13:1). The under 12 age group had the highest prevalence of tooth impaction, and the over 19 age group showed the least prevalence of tooth impaction. The ratio of tooth impaction between the left to right ratio was 1.73:1 and maxilla and mandible was 1.84:1. The impacted teeth were most commonly positioned buccally (76 cases, 41.5%). Full nap closure technique (108 cases, 81.2%)was most frequently used for attachment of surgical traction hooks. Maxillary canine impaction was most commonly encountered both in male and female patients. The mean treatment period was 12.2 months and the success rate of treatment was 90.3%. The canine tooth shows the longest treatment time and highest failure rate. The ankylosis was the major cause of failure. Conclusion: Impacted teeth most commonly show in left side maxilla in the under 12 age group. And it is most commonly positioned buccally. The mean treatment period was 12.2 months, and the success rate of treatment was 90.3%.

• 대한핵의학회지
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• 제37권4호
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• pp.235-244
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• 2003

목적: 주의력결핍 과잉행동장애 (Attention Deficit Hyperactivity disorder : 이하 ADHD)는 도파민계의 이상 기능으로 생기는 대표적 소아정신과 질환이다. Methylphenidate는 dopamine transporter(DAT)를 차단함으로써 ADHD 증상을 호전시키는 약물로 널리 알려져 있다. 따라서 본 연구에서는 ADHD 아동들을 대상으로 I-123 IPT SPECT를 이용하여 methylphenidate 투여 전후의 DAT density 양상을 비교해 보고자 한다. 대상 및 방법: 연구대상은 9명의 ADHD 아동과 7명의 정상 대조군이었다. ADHD 아동군과 정상 대조군에게 모두 약물 비노출 상태에서 $[^{123}I]IPT$를 정맥 주사후 2시간이 경과한 상태에서 SPECT를 촬영하였다. 이후 ADHD 아동군을 대상으로 methylphenidate 0.7mg/kg/d을 투여한 후 약 8주가 경과한 상태에서 $[^{123}I]IPT$ SPECT를 재촬영 하였다. Methylphenidate 투여 전과 후의 좌, 우측 기저 신경절 DAT 특이결합/비특이결합 비율을 구한 뒤 비교하였고, 약물 투여 후의 ADHD 증상 척도로 측정한 증상 호전도와 좌, 우측 기저 신경절 DAT 특이결합/비특이결합 비율 변화사이의 상관관계를 알아보았다. 결과: ADHD 아동군에서 약물 비노출 상태와 정상 대조군 사이의 좌, 우측 기저 신경절 DAT특이결합/비특이결합 비율을 비교한 결과 DAT 결합 비율이 정상 대조군에 비해서 유의하게 증가되었다. (Right : z=2.057, p=0.041 ; Left z=2.096, p=0.032). 또한 ADHD 아동들에게 methylphenidate 투여 전과 후 상태에서의 기저 신경절 DAT 특이결합/비특이결합 비율을 비교한 결과, methylphenidate 투여 후 상태가 methylphenidate 투여 전 상태에 비해 좌, 우측 DAT 결합비율이 유의하게 낮아진 것을 관찰할 수 있었다. (우측 : t=3.239, p=0.018 ; 좌측 : t=3.133, p=0.020). ADHD 증상의 호전도와 좌, 우측 기저 신경절 DAT 특이결합/비특이결합 비율 변하사이에는 유의한 상관관계를 보이지 않았다. 결론: 이러한 결과는 주의력결핍 과잉행동장애의 치료제인 methylphenidate가 작용하는 기전을 이용하여 주의력결핍 과잉행동장애의 병태생리와 연관된 도파민계 기능이상 가능성을 지지한다고 생각된다.

• 대한의용생체공학회:의공학회지
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• 제30권6호
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• pp.521-528
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• 2009

This study is about to evaluation of postural stability according to characteristics of electrical stimulation on the ankle muscles. We measured body sway(center of pressure, COP) when various parameters of electrical stimulation was applied to ankle muscles in stable and unstable posture. Subjects consisted of 10 young adults, and electrical stimulation was delivered on right and left of tibialis anterior and Achilles tendon. The body sway was measured during electrical stimulation of three duty cycle and frequencies in stable posture and three amplitudes of sensory threshold in unstable posture. Consequently, the COP Shift is higher during electrical stimulation of 1/30(duty ratio) and 100Hz(frequency) in stable posture. In unstable posture, 100% amplitude of sensory threshold induced postural stability. These findings are important for the rehabilitation system of postural stability and the use of electrical stimulation as somatosensory information.

• Journal of Chest Surgery
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• 제29권9호
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• pp.945-950
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• 1996

경북대학교병원 흉부외과학교실에서 1982년 4월부터 1995년 3월사이에 개심술을 시행하였던 좌심실-우심방 단락 12례에 대한 치료경험을 보고한다. 환자들의 연령은 3세에서 26세까지로, 평균연령은 8.5세 이 었고, 성별은 남자가 7명, 여자가 5명이었다. 술전의 단순흉부 X-선소견상 심흉비의 평균치는 0.59이었고, 폐혈관음영의 증가가 3례, 우심방의 확장이 4례에서 있었다. 기록을 확인할 수 있었던 9례에서의 술전 심초음파검사소견에 의하면, 진단명은 좌심실-우심방 단락 2례, 심실중격결손 6례 및 심방중격 결손 1례로 되어 있었다. 따라서 이 검사에 의한 좌심실-우심방판락의 진단률은 22.2%(219)였다. 술전의 심혈 관조영소견으로는, 좌심실-우심방 단락 5례, 심실중격결손 5례, 심방중격결손 1례, 그리고 심실중격 결손 및 심방중격결손 1례로 진단되었다. 그러므로 이 검사에 의한 진단률은 41.6% (5112)였다. 수술소견상, 좌심실-우심방 단락의 형태는 판막상부형 결손 5례(42%), 판막하부형 결손4례(33%)및 복합형 결손3 례 (25%)로 분류되었다. 한편 판막하부형 결손례들은 모두 삼첨 판막 중격엽의 이상을 동반하고 있었는데, 즉 천공이 3례, 구열\ulcorner 1례에서 있었다. 그러나 판막상부형이나 복합형 결손에서는 삼첨판의 이상은 볼 수 없었다. 수술은 1례를 제외하고는 모두 우심방절개하에 결손부의 일차봉합을 시행하였고, 수술사 망례는 없었다. 그러나 잔존 심실중격 결손이 1례에서 발견되어 술후 6개월에 재수술을 시행하여 완치되었다. 그밖의 환자들에서의 술후 경과는 모두 양호하였다.

• 한국안전학회지
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• 제25권3호
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• pp.15-21
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• 2010

A differential case equipped with LSD(limited slip differential) has several advantages over a normal type for rear wheel drive vehicles. Specially, the torque distribution can be done between left and right drive wheel in the state of limited slip differential. Also although LSD types are very various according to operating type, medium and torque distribution, a multi-clutch type is generally applied to rear wheel drive vehicles. So, this study presents the analysis of design parameters for development of a friction plate for multi-clutch type LSD using vehicle road test, the simulation of analytical model and the development of vehicle dynamics model by a benchmark product. According to this investigation, the design parameters which are pre-load of coil spring, friction plate and contact area quantity, friction coefficient and TBR(torque bias ratio) for a friction plate are derived from experiment and simulation and consequently, vehicle dynamics model has been constructed for the development of friction plate for multi-clutch type LSD.