역문제에 의한 구조물의 실동하중 해석

송준혁,노홍길,김홍건,유효선,강희용,양성모 한국공작기계학회 2004 한국생산제조학회지 Vol.13 No.2

Vehicle structures are composed of m y substructures connected to one another by various types of mechanical joints. In vehicle engineering, it is important to study these connected structures under various dynamic forces for the evaluations of fatigue life and stress concentration exactly. It is difficult to obtain the accurate load history of specified positions because of the errors such as modeling, measurement, and etc. In the beginning of design, exact load data are actually necessary for the fatigue strength and life analysis to minimize the cost and time of designing. In this paper, the procedure of practical dynamic force determination is developed by the combination of the principal stresses of F. E. Analysis and experiment. Least square pseudo inverse matrix is adopted to obtain an inverse matrix of analyzed stresses matrix. The error minimization method utilizes the inaccurate measured error and the shifting error that the whole data is stiffed over real data. The least square criterion is adopted to avoid these errors. Finally, to verify the proposed procedure, a bus is analyzed. This measurement and prediction technology can be extended to the structural modification of any geometric shape in complex structure.

Revisiting Social Discount Rates for Public Investment

송준혁 한국개발연구원 2017 KDI Journal of Economic Policy (KDI JEP) Vol.39 No.2

This paper aims to estimate the social discount rate (SDR) rather than dig into its theoretical foundation. As SDRs can be derived by investigating both the rate of return on investment and the social time preference rate, we estimate the marginal productivity of both private and public capital and the time preference rate based on the Euler equation. In order to provide a single representative SDR, the weighted averages of the marginal productivity and time preference rate, whose weights are determined by the flow of funds data reflecting the social demand of funds, are presented. Based on the empirical results, we argue that the marginal productivity of private capital stands in the middle of the 3% range while that of public capital varies from 4.5% to 8.6%, with the time preference rate showing a decreasing trend from 3.2% in the early 2000s to 1.2% by around 2030. The single representative SDR or the weighted SDR is estimated to be approximately 3.0~4.5% and expected to continue its downward trend for the foreseeable future.

Truck Frame 결합부의 강도평가에 관한 연구

송준혁,김종규,강희용,양성모 전북대학교 공업기술연구소 1998 工學硏究 Vol.29 No.-

A structural joint represents a critical element in virtually all hardware. The mechanical fastened joint of bolted type is probably the most established and formalized design methodology at the present time. An overall analysis of the structure or structural component has been performed to determine the joint design loads and the internal load distribution. In this paper, a finite element analysis is conducted to obtain the effective joint load with the internal load distribution for 2.5T truck frame. The joint external loads are determined by the analysis of overall structures and each substructure with the joint. Using the proposed procedure, designers are able to obtain the criterion and optimization of any new developing or modified structures.

소뇌 핍지-성상세포 혼합종에 합병된 경수 척수공동증 : 증례보고 A Case Report

송준혁,정용구,이기찬,이훈갑 대한신경외과학회 1995 Journal of Korean neurosurgical society Vol.24 No.6

The authors present a case of cervical syringomyelia associated with cerebellar mixed oligo-astrocytoma in an 18-month-old boy who was normally delivered at full-term. The child presented with an increasing incidence of vomiting and irritability, and a poor truncal control. Preoperative magnetic resonance imaging of the brain revealed cerebellar vermian tumor with an obstructive hydrocephalus and a small-sized syringomyelia at the 6th cervical vertebral level. The tumor was completely removed via suboccipital craniectomy. Histologically, the tumor consisted of mixed oligo-astrocytoma. The cervical syringomyelia was conservatively managed with no specific operative treatment. At two months postoperatively, magnetic resonance imaging of the cervical spine showed a remarkable reduction in size of the syringomyelic cavity.

요추 추간판 탈출증에서 황색 인대 보존 현미경 수술법의 임상 분석

송준혁 梨花女子大學校 醫科大學 醫科學硏究所 2000 EMJ (Ewha medical journal) Vol.23 No.2

Objectives : The microdiskectomy was developed out of attempts to refine the classical lumbar laminectomy and diskectomy. The ligament-sparing microdiskectomy, a more refined technique, was developed by the author. For this study a series of patients, operated by the present author, were reviewed. Methods : Consecutive patients admitted to Ewha Mokdong hospital between August 1997 and June 2000 who were to undergo virgin, unilateral single-level lumbar ligament-sparing microdiskectomy undergoing unilateral single-level microdiskectomies were included. The technique of the ligament-sparing diskectomy was described in detail. Results : A total of 83 patients were operated on(M : F/63 : 21), with an average age of 37.2 years. Successful outcome was achieved in 78 patients(93.9%). Surgical complications included one wound infection and one reoperation for residual disk herniation. Conclusion : The author believe that this technique is safe, can provide acceptable clinical outcome, and has an additional advantage of preserving the epidural fat.

이자율기간구조를 이용한 기대인플레이션의 추정 및 특징

송준혁 한국국제경제학회 2013 한국국제경제학회 학술대회발표 논문집 Vol.2013 No.4

본 연구에서는 거시 및 재무모형을 이용하여 우리나라 기대인플레이션을 추정하고자 한다. 기대인플레이션을 찾기 위한 방법으로는 일반적으로 거시 모형을 기반으로 수익률 정보를 활용하는 것과 재무 모형을 중심으로 거시 정보를 활용하는 방법으로 대별된다. 재무 모형의 경우에는 거시 변수에 적절한 확률 과정을 부여하고 이를 가격함수에 직접 대입한 뒤 최종적으로 자산가격 PDE를 도출하는 방법이고, 거시 모형을 기반으로 하는 경우에는 거시 변수와 금리 변수를 포함한 VAR을 구축한 뒤 이중 일부 변수를 은닉 요인으로 처리함으로써 무차익 거래 조건을 유지하면서 거시 변수를 도입하는 방법이다. 본고에서는 이들 두 방식을 모두 이용하여 재무와 거시 변수를 통한 우리나라 기대인플레이션의 시계열을 추출하고 그 추이를 살펴보고자 한다. 분석 결과 우리나라의 기대인플레이션은 글로벌 금융위기 이전에는 4%를 상회하는 높은 수준을 보였으나 2008년 후반을 기점으로 하여 상당폭 하락하는 모습을 시현하였다. 2009년 초 저점 이후 기대인플레이션은 반전하여 2012년 초까지는 증가하였으나 이후 다시 약화되는 모습을 시현하였다. 또한 본고에서는 재무모형에서 도출된 기대인플레이션과 실제 자료로 입수 가능한 기대인플레이션간의 비교를 통해 우리나라 기대인플레이션의 특징을 살펴보았다. 경제 주체의 기대인플레이션 형성에 체계적인 편의가 존재하지 않고(불편성), 기대 형성에 활용가능한 모든 정보가 반영되었는지(효율성)를 기준으로 합리성을 평가한 결과 분석에 이용된 모든 기대인플레이션에서 이러한 합리성이 모두 기각되는 것으로 나타났다. 한편 실제 인플레이션과 기대인플레이션간의 Granger 인과검정 결과 대체로 실제 인플레이션은 단기 기대인플레이션에, 기대 인플레이션은 장기 실제 인플레이션에 통계적으로 유의한 영향을 미치고 있음이 관찰되었다.

Cortical Spreading Depression과 Aspartate및 Glutamate와의 연관관계에 대한 실험적 연구

송준혁,박윤관,정용구,정흥섭,서중근,이기찬,이훈갑 대한신경외과학회 1996 Journal of Korean neurosurgical society Vol.25 No.2

The author has examined the effect of cortical spreading depression(CSD) on the changes in extracellular concentration of aspartate and glutamate in the neocortex ofanesthetized rats using microdialysis and high performance liquid chromatography(HPLC). The rats were prepared by halothane anesthesia and artificial ventilation. Rats were placed in a stereotaxic frame, and craniotomies were performed over the frontal and parietal cortices on one side. The CSD was elicited by local application of KCI-soaked small pellets to the frontal cortex. The CSD was monitored by the changes of direct current(DC) potential in the parietal cortex. The microdialysis probe was implanted in the anterior part of the parietal cortex. Amino acids were analyzed by HPLC and fluorescence detection. Baseline concentration of the aspartate was 34.9±15.9nM and that of glutamate was 189.9±29.1nM(mean standard deviation). The perfusate for analysis was obtained 30 minutes after the beginning of the 300mM KCI induced CSD. Aspartate was found to increase to 146±55% baseline, glutamate up to 173±30% baseline (mean standard deviation). The increment of glutamate was statistically significant(p<0.05). Then 2M KCI-soaked pellets were applied for more frequent CSD and the samples were collected. Aspartate increeased up to 258±97% baseline, glutamate up to 174±57% baseline (mean standard deviation). The increment of glutamate and aspartate accompanying 2M KCI induced CSD were also statistically significant (p<0.05). These data suggest that the excitatory amino acids were released during the CSD and this may explain the various aspects of CSD that could contribute to the secondary neuronal damage in the compromised nerve cell.

Dual Mass Flywheel 시스템의 설계 파라미터에 관한 연구

송준혁,강희용,홍동표,양성모 한국생산제조학회 1996 한국공작기계학회 추계학술대회논문집 Vol.1996 No.-

KOSPI200 변동성의 장기기억 모형과 국면전환 모형간 예측력 비교 분석

송준혁 한국은행 2011 經濟分析 Vol.17 No.4

This paper investigates the long memory property of KOSPI200 volatility and compare the forecasting power between the long memory and regime switching models. When no regime-switching is assumed, the realized volatility and VKOSPI show no signs of permanent memory, but suggest that both of them have stationary long memory properties. Long memory can be spurious in the presence of structural or regime changes. In order to see this, 1-day and 5-day ahead volatility forecasting test, based on Diebold-Mariano(1995), are conducted to compare model prediction power between long memory and regime-switching models. The test shows that regime-switching model is more accurate in 1-day ahead realized volatility forecasting, while 1-day ahead forecasting shows no difference between the models. It suggests that long memory process of stock volatility can be better understood when structural-changing features of the volatility are given more attention. 본 논문에서는 KOSPI200 지수 변동성의 장기기억 속성을 분석하는 한편 장기기억과 레짐 스위칭 모형간의 예측력에 대한 실증 분석을 수행하였다. 레짐의 변화를 고려하지 않은 상태에서 실현변동성과 VKOSPI를 대상으로 단위근 검정을 수행한 결과 단위근의 존재는 발견되지는 않았으나, ARFIMA 모형을 이용하여 추정한 결과 이들 변동성들은 안정적인 장기기억 과정인 것으로 분석되었다. 장기기억 과정은 시계열에 구조 변화가 존재할 경우 가성적(spurious) 현상일 수 있다. 실제로 이를 검정하기 위해 구조 변화를 고려한 마코프 스위칭모형과 1일 및 5일 이후의 예측성과를 Diebold-Mariano(1995) 검정을 통해 살펴본 결과 실현변동성의 1일 예측에서는 마코프 스위칭모형의 예측력이 높게 나타난 반면 그 외의 경우에서는 두 모형간의 큰 차이는 발견되지 않았다. 이러한 결과는 장기기억 과정에 대한 이해를 높이기 위해서는 구조적 변화가 변동성에 가지는 의미에 관심을 둘 필요가 있음을 시사한다.

Actazolamide와 Fluphenazine의 뇌척수액 생성에 대한 효과

송준혁,박윤관,정흥섭,서중근,이훈갑,이기찬,주정화 대한신경외과학회 1993 Journal of Korean neurosurgical society Vol.22 No.10

The purpose of this study was to investigate the effect of acetazolamide and fluphenazine on the formation of CSF. Studies were performed in 12 cats those were divided into 2 groups ; A-F group included animals received initial acetazolamide infusion and additional infusion of fluphenazine to the initial infusion and the F-A group for vice versa. The rate of CSF formation was measured at 3㎝ above zero outflow pressure by force transducer which connected to personal computer. After obtaining steady value of CSF formation rate, the drugs were infused intravenously according to the protocol. Base line CSF formation rate, 18.87±6.52μl/min, is reduced to 6.67±2.45μl/min after acetazolamide infusion and further reduced to 3.48±4.06μl/min after additional fluphenaxine. In fluphenazine group, the base line CSF formation rate, 16.34±4.58μl/min is reduced to 9.63±4.58μl/min after initial infusion of fluphenazine and further to 6.45±3.64μl/min, after additional infusion of acetazolamide. Mean reduction of CSF formation after initial intravenous infusion of acetazolamide and fluphenazine were 59% and 37% respectively. Although statistically insignificant, the CSF formation reduction in A-F group revealed more even and profound value comparing with that of F-A group. These date suggest that in addition to the effect of acetazolamide to reduce the formation of CSF, some other mechanism may exist in CSF formation that major tranquilizer exert the effect on CSF formation.