병원 밖 심정지 환자에서 뇌출혈 유무에 따른 특징 및 예후 차이 분석: 후향적 분석

장연식,임용수,조진성,김진주,현성열,양혁준,이근 대한응급의학회 2013 대한응급의학회지 Vol.24 No.2

Purpose: Spontaneous intracranial hemorrhage (ICH) is not an uncommon cause of cardiac arrest. The purpose of this study was to identify the prognosis of patients with ICH for Out-of-Hospital Cardiac arrest (OHCA). Methods: From January 2008 to December 2010, a total of 214 patients were checked brain computed tomography (CT) in OHCA. The majority of patients were male (136,63.8%), and the median age was 55.0 (±16.7). We included all patients who were checked through brain CT for nontraumatic OHCA. Data were collected from electronic medical records and pre-hospital records. Demographic, clinical and laboratory data were compared between the ICH and non-ICH group. Results: The detection of ICH by clinical manifestations and laboratory data was difficult. Out of 214 patients, 21(9.8%) patients were positive for ICH and 193(90.2%)patients had a normal brain CT. In demographic and clinical data, the neurological outcome (CPC score, p=0.009) and 30-day survival rate (p<0.001) were statistically different between the two groups. Using the Cox proportional hazards model, the ICH group had a 3.54 hazard ratio compared with non-ICH group. In addition, pH (p=0.033), lactate (p=0.023) in ABGA, potassium (p=0.008), glucose (p=0.026), and S-100 (p=0.047) showed significant results. Conclusion: The prognosis of ICH patients in OHCA is poor; further studies are needed to improve the prognosis of ICH patients after ROSC in OHCA.

S&P500 지수, Emini S&P500 지수선물, KOSPI200 간의 정보이전 효과

장연식,오형식 대한산업공학회 2010 대한산업공학회 추계학술대회논문집 Vol.2010 No.11

본 논문에서는 미 국의 정규장 시간에 거래되는 S&P500 지수 및 미국 정규장이 끝난 이후의 거래되는 E-mini S&P500 이 각각 한국 시장에 정보이전 효과를 가져오는지 실증분석 하였다. 또한 전날 장이 끝나고 발생한 정보가 모두 시가에 반영되는지 아니면 장중에도 지속적으로 영향을 끼치는지 분석하였다. 분석 모델로는 MA(1)-GARCH(1,1) in Mean 과 MA(1) -GARCH(1,1) wi t h Regres s ion을 이용하였다. 우리의 실증적 분석결과는 다음과 같다 . 본 연구결과 첫째 , 미국 정규장이 끝난 후에 거래되는 E-mini S&P500 지수선물은 S&P500 지수와 정보이전 효과를 지닌다는 결과가 도출되었다. 둘째, S&P500 지수의 정보이전은 장시작과 해소되는 경향이 있고 , 한국시장에서 과민반응을 보이는 결과가 도출되었다. 셋째, E-mini S&P500 의 정보이전은 장시작과 동시에 모두 해소되지 않고, 장중 지속적인 영향을 끼친다는 결과가 도출되었다. 넷째 변동성의 비대칭적인 현상은 리만사태 이후 더욱 강력해졌다는 결과가 나타났다.

부모와의 의사소통이 대학생의 행복감에 미치는 영향: 자아정체성의 매개효과를 중심으로

장연식 한국복지상담교육학회 2016 복지상담교육연구 Vol.5 No.2

This study aims to examine the effect on college students’ happiness of their communication with their parents and verify the mediating relations of ego-identity. As for variables influencing college students’ happiness, their communication with their parents was set as an independent variable, while ego-identity was a mediating variable. A survey of 437 college students, from freshmen to seniors, who attend colleges in the central part of Korea was conducted, and the results were used for this study. Data were analyzed with the SPSS win 21.0 descriptive statistics software. The exploratory factor analysis was carried out with Cronbach’s alpha, correlation analysis, and frequency, hierarchical regression, was used to conduct the cleansing work with the most appropriate measurement variable. Regression analysis was conducted for the mediating effect, and hierarchical regression analysis was conducted to determine the causal relationship among observed variables. As a result of this study, the variable that directly influences college students’ sense of happiness was found to be their communication with their parents, and ego-identity was identified as a relevant variable with an indirect mediating effect. It was therefore concluded that college students’ happiness is directly influenced by their communication with their parents and indirectly through ego-identity. 본 연구는 부모와의 의사소통이 대학생의 행복감에 미치는 영향에서 자아정체성의 매개효과를 검증하는데 그 목적이 있다. 대학생의 행복감에 영향을 미치는 변인으로서는 부모와의 의사소통을 독립변수로 하고 자아정체성을 매개변수로 설정하였다. 연구의 방법으로는 우리나라 중부권에 재학하고 있는 대학생 1∼4학년 437명을 대상으로 설문조사한 결과의 내용을 사용하였다. 자료의 처리는 SPSS 21.0 프로그램을 이용하여 기술통계, 상관분석, Cronbach’s α,계수를 산출하였으며, 매개효과를 위해서 회귀분석을 실시하였으며, 측정변인들의 인과관계의 추론을 위해서 위계적 회귀분석을 실시하였다. 연구결과로서 대학생의 행복감에 직접적인 영향을 미치는 변인은 부모와의 의사소통이며, 간접적인 영향력의 매개효과는 자아정체성이 관련변인으로 확인되었다. 따라서 부모와의 의사소통은 대학생의 행복감에 직접적인 영향을 미치고, 자아정체성을 통해서 간접적인 영향을 미친다는 결론을 얻었다.

Sensitivity of Suspension Pattern of Numerically Simulated Sediments to Oscillating Periods of Channel Flows over a Rippled Bed

장연식,황진환,박영규 대한토목학회 2017 KSCE JOURNAL OF CIVIL ENGINEERING Vol.21 No.5

In this study, we investigated the sediment suspension process over a ripple, using large eddy simulation and a Lagrangian particle tracking model to numerically calculate the individual motion of sediment grains in turbulent boundary layer flows. We examined the relationship of the sediment convection process with the formation of lee eddies at the back of the ripple. We tested three flow conditions by changing the oscillating period while keeping other conditions. In all three cases lee eddies developed, but they formed at different flow phases and differed in their duration. These lee eddies significantly influenced the turbulent kinetic energy distribution and sediment suspension pattern as they showed phase differences between the cases, according to their lee eddy formation. We compared two types of sediment suspension rates by counting the number of suspended sediment grains. Both these rates showed that maximum sediment pick-up occurred earlier in the oscillating flow phase as the period increased, but the magnitude of the pick-up rate decreased with increasing period. The results of our study indicate that the suspension pattern may vary significantly with the period. Therefore, formulas for sediment pick-up rates, which usually give maximum rates at the time of flow reversal over ripples, may require an additional controlling factor—the oscillation period. The sediment suspension pattern, however, shows some discrepancies from that observed by van der Werf et al. (2007) as the sediments were not suspended at the time of flow reversal. This is likely due to the low steepness of the ripple and the employment of an unrealistically small sediment size in our study experiment.

실물옵션을 통한 신재생에너지 가치평가

장연식,이덕주,오형식 대한산업공학회 2011 대한산업공학회 춘계학술대회논문집 Vol.2011 No.5

For recent several years, the oil price has fluctuated due to the weak dollar and financial risk. Specially, WTI crude oil price recorded $147 per barrel in July 2008 which is the highest record in the history. And climate change concerns are driving to increase R&D about alternative energy instead of fossil energy. To evaluate the R&D of renewal energy, we need to calculate the net present value and also the insurance value of the R&D. In this paper we evaluate the renewable energy R&D with real option method which considers the uncertainty of fossil energy and the uncertainty of renewal energy R&D success. We assume that the fossil price follows geometric mean reverting process and the success probability of renewal energy R&D follows binomial probability model. We also consider option to abandon R&D, option to deploy R&D, option to delay R&D, and option to continue R&D in our model. And we analyze the value of Korean renewal energy R&D using this model.

KOPSI200 시장에서 변동성 및 상관계수의 비대칭성과 수익률

장연식,최규원,권수정,오형식 대한산업공학회 2010 대한산업공학회 추계학술대회논문집 Vol.2010 No.11

본 논문에서는 KOSPI200 주가 데이터를 가지고 수익률과 변동성 및 상관계수에 관한 실증적 분석을 하였다. 그 결과 우리는 다음 결론을 도출하였다. 첫째, 변동성과 수익률은 음의 상관관계가 나타났다. 둘째, 주식보다 지수에서 변동성의 비대칭적 현상이 뚜렷이 나타났다. 셋째, 수익률과 변동성간의 관계는 주로 전날 종가와 아침시가사이의 불연속적인 갭 구간에서 발생했다. 넷째, 개별 주식들 간의 상관계수와 지수 수익률 간에는 음의 상관관계 나타났다. 이는 시장이 상승할 때보다 하락 때 포트폴리오의 분산 효과가 줄어들 수 있음을 시사한다.

Measurement of Turbulence Properties at the Time of Flow Reversal Under High Wave Conditions in Hujeong Beach

장연식,도종대,김선신,안경모,진재율,Chang, Yeon S.,Do, Jong Dae,Kim, Sun-Sin,Ahn, Kyungmo,Jin, Jae-Youll Korean Society of Coastal and Ocean Engineers 2017 한국해안해양공학회 논문집 Vol.29 No.4

교란운동에너지(TKE)와 레이놀즈 응력의 수직성분($-{\bar{u^{\prime}w^{\prime}}}$)에 대한 한 주기 파장 안에서의 시간변화를 관측자료를 사용하여 분석하였다. 관측자료는 동해에서 온대성저기압이 발달하였던 2017년 1월 14일부터 18일까지 동해안 후정해변에서 측정한 파랑자료를 사용하였다. 이 기간 동안 관측된 모든 파랑자료들 중에서 비슷한 형태를 갖는 수백 개의 규칙파들을 구분하였으며 이 자료를 토대로 Ensemble Average 기법을 사용하여 이 기간 파랑특성을 대표하는 세 개의 평균파를 계산하였다. 그리고 이 평균파를 기준으로 각 파의 요동을 측정하여 한 주기 동안의 교란운동에너지와 레이놀즈 응력을 계산하였다. 이렇게 계산된 자료들을 분석한 결과 교란운동에너지는 파랑의 평균유속과 비슷한 분포를 나타내었으나(즉 유속이 최대값을 나타낼 때 교란운동에너지도 최대값을 나타내었다), $-{\bar{u^{\prime}w^{\prime}}}$는 파랑의 수평유속 방향이 전환되는 '방향전환점'에서 가파르게 증가하는 경향을 나타내었다. 이러한 $-{\bar{u^{\prime}w^{\prime}}}$의 독특한 분포는 Nielsen(1992)에 의해 제안된 난류 convection 현상을 뒷받침하는 발견으로 퇴적물과 같은 물질들의 부유현상이 파랑의 '방향전환점(한 주기 안에서 파랑의 횡단방향 유속 부호가 바뀌는 시점)'에서 촉진될 수 있음을 보여준다. 이렇게 관측된 난류에너지 분포 특성을 CADMAS-SURF 모델을 사용하여 구현해 보았다. 그 결과 교란운동에너지의 경우 모델결과와 관측치 사이에 유사성이 발견되었으나 레이놀즈 응력($-{\bar{u^{\prime}w^{\prime}}}$)의 경우 모델이 '방향전환점'에서의 증가현상을 구현해 내지 못하였다. 이는 CADMAS-SURF와 같은 Reynolds-Averaged Navier-Stokes(RANS) 모델들이 가지는 한계점으로 RANS 모델의 경우 레이놀즈 응력과 같은 난류에너지가 평균유속의 분포에 강한 영향을 받기 때문인 것으로 판명되었다. The temporal distribution of the turbulence kinetic energy (TKE) and the vertical component of Reynolds stresses ($-{\bar{u^{\prime}w^{\prime}}}$) was measured during one wave period under high wave energy conditions. The wave data were obtained at Hujeong Beach in the east coast of Korea at January 14~18 of 2017 when an extratropical cyclone was developed in the East Sea. Among the whole thousands of waves measured during the period, hundreds of regular waves that had with similar pattern were selected for the analysis in order to give three representing mean wave patterns using the ensemble average technique. The turbulence properties were then estimated based on the selected wave data. It is interesting to find out that $-{\bar{u^{\prime}w^{\prime}}}$ has one clear peak near the time of flow reversal while TKE has two peaks at the corresponding times of maximum cross-shore velocity magnitudes. The distinguished pattern of Reynolds stress indicates that vertical fluxes of such properties as suspended sediments may be enhanced at the time when the horizontal flow direction is reversed to disturb the flows, supporting the turbulence convection process proposed by Nielsen (1992). The characteristic patterns of turbulence properties are examined using the CADMAS-SURF Reynolds-Averaged Navier-Stokes (RANS) model. Although the model can reasonably simulate the distribution of TKE pattern, it fails to produce the $-{\bar{u^{\prime}w^{\prime}}}$ peak at the time of flow reversal, which indicates that the application of RANS model is limited in the prediction of some turbulence properties such as Reynolds stresses.

Suspension of Sediment Particles over a Ripple due to Turbulent Convection under Unsteady Flow Conditions

장연식,박영규 한국해양과학기술원 2016 Ocean science journal Vol.51 No.1

We analyzed the motions of small sediment particles over a sinusoidal ripple due to an unsteady turbulent boundary layer flow using Large Eddy Simulation. The motions of sediment particles are described in terms of the Lagrangian framework as it is helpful in studying the structure of sediment suspension in detail. Strong coherent vortical structures are well developed along the upslope of the ripple surface during the accelerating flow phase, which effectively drag the particles to the ripple crest. At the maximum flow rate and at the decelerating flow phase, a cloud of vortical structures is developed vertically in the lee area of the ripple. Sediment particles render strong dispersion in the vertical direction when they are captured by these turbulent vortices, causing convective sediment flux that cannot be explained by the mean flows. The convective sediment suspension is strongest at the time of flow deceleration, while over a flat bed at the time of flow reversal. This observation suggests that bed form effect should be considered in modeling convective sediment flux.

Seasonal Variation of Submesoscale Flow Features in a Mesoscale Eddy-dominant Region in the East Sea

장연식,최병주,박영규 한국해양과학기술원 2018 Ocean science journal Vol.53 No.2

Seasonal changes in the distribution of submesoscale (SM) flow features were examined using a fine-resolution numerical simulation. The SM flows are expected to be strong where mesoscale (MS) eddies actively develop and also when the mixed layer depth (MLD) is deep due to enhanced baroclinic instability. In the East Sea (ES), MS eddies more actively develop in summer while the MLD is deeper in winter, which provided the motivation to conduct this study to test the effects of MLD and MS eddies on the SM activity in this region. Finite-scale Liapunov exponents and the vertical velocity components were employed to analyze the SM activities. It was found that the SM intensity was marked by seasonality: it is stronger in winter when the mixed layer is deep but weaker in summer - despite the greater eddy kinetic energy. This is because in summer the mixed layer is so thin that there is not enough available potential energy. When the SM activity was quantified based on parameterization, (MLD × density gradient), it was determined that the seasonal variation of MLD plays a more important role than the lateral density gradient variation on SM flow motion in the ES.

이중과제수행이 뇌졸중 환자의 체간조절능력과 상지기능에 미치는 효과

장연식,백지영,오명화,이성아 한국장애인재활협회 2012 재활복지 Vol.16 No.2

This study was to investigate the effect of dual task performance on the trunk control ability and upper extremity function of chronic stroke patients. Thirty subjects after six month post stroke and they are divided into two groups of dual task performance and single task performance, each fifteen patients in a random selection for 30-min sessions 5 times every week during 8 week. For the function restoration of the subject, it was measured of the trunk control ability by using TIS and PASS, and it was measured of upper extremity function by using KWMFT and CMS-10. The results of this study were as follows. First, after the dual task performance program, the trunk control ability showed statistically significant differences. Second, after the dual task performance program, the upper extremity function showed statically significant differences. Third, in the surveyed comparison result between dual task group and single task group, trunk control ability and upper extremity function was significant differences. Thus, the dual task performance applied to the stroke patients must be one of the effective treatments on trunk control ability and upper extremity function of the stroke patients. 본 연구는 이중과제 수행이 뇌졸중 환자의 체간조절능력과 상지기능에 미치는 효과를 알아보고자 한다. 연구대상은 대상자 선정기준에 맞는 편마비 환자 총 30명을 대상으로 이중과제 수행군과 단일과제 수행군 각각 15명씩 무작위로 나누어 총 8주 동안 주 5회 30분 프로그램을 적용하였다. 대상자의 기능회복을 알아보기 위해 체간 손상 척도(Trunk Impaired scale)와 뇌졸중 환자의 자세조절 능력검사(Postural Assessment Scale for Stroke)를 사용하여 체간조절능력을 측정하였고, 한글판 울프 운동 기능 검사(Korean Wolf motor function test)와 삼차원 동작분석 시스템(3-dimensional motion analysis system, CMS-10)을 이용하여 실험 전과 실험 후의 상지기능을 측정하였다. 이에 대한 연구 결과는 다음과 같았다. 첫째, 이중과제 수행군과 단일과제 수행군의 각 실험 전․후 체간조절능력은 통계학적으로 유의한 차이를 보였다. 둘째, 이중과제 수행군과 단일과제 수행군의 각 실험 전․후 상지기능은 통계학적으로 유의한 차이를 보였다. 셋째, 이중과제 수행군과 단일과제 수행군의 두 군 간의 차이를 비교한 결과 체간조절능력과 상지기능에 통계학적으로 유의한 차이를 보였다. 따라서 이중과제수행은 뇌졸중 환자의 체간조절능력과 상지기능 향상에 효과적인 치료방법 중의 하나임을 알 수 있었다.