• Journal of Chest Surgery
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• v.19 no.4
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• pp.606-617
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• 1986

During the period from November 1981 through June 1986, 18 cases of coronary arterial bypass graft were performed at Department of Thoracic and Cardiovascular Surgery, Seoul National University Hospital. They consisted of 13 males and 5 females with the mean age of 49 [range: 28-69 years]. History of myocardial infarction was noted in 50% of the patients and cardiomegaly on chest PA in 2 patients with preserved LV function. On resting EKG, except the evidences of old myocardial infarction, the findings of LVH were noted in 7 cases, acute myocardial infarction in 2, diffuse myocardial ischemia in 1, and significant ventricular arrhythmia in 2 cases. The angina by type of presentation is stable in 3 patients, unstable in 15 patients with resting, postinfarction and progressive angina as the criteria of unstability. The patterns of involvement of significant disease were single vessel involvement [5 cases] double vessel involvement [8 cases], and triple vessel involvement [5 cases] including 5 cases of left main coronary arterial diseases. The pattern of coronary arterial disease in individual patient was one or more stenosis of the proximal left coronary arterial system with or without right coronary involvement, in every case. We performed 9 cases of double bypass and 9 cases of triple bypass with great saphenous vein using single anastomosis technique except in 4 cases, One of the 4 cases is our first case, sequential anastomosis between LAD and diagonal was performed due to shortage of the prepared vein graft. In the other 3 cases, our latest experience, we adopted the left internal mammary artery for the left anterior descending coronary revascularization. The distribution of sites of distal anastomosis revealed more striking predilection to LAD, showing our attention on the significance of the revascularization of LAD system. The ischemic time was 35 minutes per graft and mean number of grafts per patient was 2.5. Of the 18 patients, 13 [77.2%] had complete revascularization, and incomplete in 5 cases with the causes of incompleteness as presented. The early results of operation were as followed: surgical death in 2 [11%], perioperative infarction 2 [11%], need of inotropic support 5 [28%], arrhythmia 2 [11%], wound problem, bleeding, and emotional dysfunction. The actuarial anginal free survival during the period of 6 months through 2 years was 85.2% with excellent symptomatic control according to the angina classification of Canadian Cardiovascular Society.

• Journal of Chest Surgery
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• v.22 no.6
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• pp.1092-1100
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• 1989

Since May 1987 to April 1989, fifteen patients have been subjected to coronary artery bypass graft [CABG] including coronary thromboendarterectomy in 3 patients at Hanyang University Hospital. The correlation between the preoperative coronary angiography, electrocardiography, clinical status, operative finding and postoperative blood flow, complication and degree of clinical improvement were evaluated. 1. Ten patients [67 %] were male and five patients [33 %] were female, Ages ranged from 30 to 68 years. [average 52.2 years] 2. The angina by types of presentation was stable in 3 patients, unstable in 12 patients with resting, postinfarction and progressive angina as the criteria of unstability. 3. The number of involved vessels were single in 6 cases, double in 4 cases, triple in 5 cases including 1 case of left main coronary arterial disease. 4. The distribution of sites of distal anastomosis revealed predilection to left coronary arterial system [83 %], especially left anterior descending arterial system. 5. The author performed 4 cases of single bypass, 4 cases of double bypass, 5 cases of triple bypass and 2 cases of quadruple bypass. Of these 15 patients, 3 patients received coronary thromboendarterectomy, LAD in 2 patients and right coronary artery [RCA] in 1 patient. 6. The distal anastomosis were performed first with using saphenous vein grafts as conduits in all cases except 1 case using Gore-Tex conduit because of deficient in length and narrowed internal mammary artery and sequential bypass methods were employed in last 6 cases. 7. One operative death occurred and therefore, mortality rate was 6.7%. The perioperative myocardial infarction were occurred in 3 cases [20%] and its cause was supposed that they were triple vessel disease and therefore, aortic cross clamping times were relatively long. 8. All survivors were followed for 17.7 months on an average [range 5-28 months] and they have had symptomatic improvement except 1 case having mild degree of angina at 1.5 months after operation.

• Journal of the Korean Society of Physical Medicine
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• v.12 no.2
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• pp.53-57
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• 2017

PURPOSE: The purpose of study was to clear up the environmental risk factor that can be easily occurred unstability of hip during gait and one leg standing at various ramp angle. METHODS: Twenties healthy males of 69 subjects is participated in this study. Participants was measured activation on gluteus medius muscle during both conditions (walk across the ramp and one leg stand in the transverse direction) of seven different angle. The measured data were analyzed using one-way ANOVA to investigate the effect of muscle activation on the each condition. The statistical analyses were performed using SPSS ver. 18.0 and p-value less than .05 were considered significant for all cases. A post-hoc test was performed by Bonferoni method. RESULTS: The study showed that more muscle activities on gluteus medius is increased by increasing the ramp angle. Post-hoc analysis demonstrated that the peak and mean of muscle activity increased significantly with a ramp angle of $15^{\circ}$ and $25^{\circ}$ during gait and one-leg stand. CONCLUSION: According to the study results, impaired balance can be easily occurred when cross walk and one-leg stand on a ramp from higher than $15^{\circ}$, and highest risk was angle of $25^{\circ}$ or more. As a people with gluteus medius muscle weakness walks a ramp, the ramp angle has a cross relationship with the impaired balance. If people with gluteus medius weakness walk on the more than $10^{\circ}$ of ramp angle, they will need a lot of attention for prevent impaired balance.

• The Journal of Engineering Geology
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• v.17 no.4
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• pp.545-554
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• 2007

Landslides is mainly induced by a heavy rainfall, earthquake ground motion, and some other factors like soil mechanics, morphological-geological factors etc. Since the starting point of the failure seemed to be originated at a construction site in the study, it is meaningful to find out the relationship between the landslide and the construction. For this study, the slope failure factor was examined carefully to see that the original natural slope had vulnerability and that the complex ground had unstability changed by construction. A field survey was conducted on the original ground surface and filled-up ground. A laboratory test was also conducted to determine the geomechanical properties of soil samples. 2D and 3D limit equilibrium analysis with changing groundwater level were conducted at the failure depth using a seismic refraction survey. The result shows that the factor of safety is similar stability under all condition, but unstable under saturated condition.

• Journal of The Korean Society of Integrative Medicine
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• v.5 no.3
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• pp.57-61
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• 2017

Purpose : The purpose of study was to find out the environmental risk factor that can be easily occurred imbalance muscle activities according to direction for using the ramp during one legged standing. Method : The subjects were 20 normal adults with a mean age of $23.15{\pm}2.14years$ and a Body Mmass Index (BMI) of $22.74{\pm}1.07$. Participants were measured muscle activities on vastus medialis, vastus lateralis, tibialis anterior, peroneus longus during one legged stance at four conditions ramp (down ramp, up ramp, medial ramp, lateral ramp). The statistical analyses were performed using IBM SPSS(Ver. 23) and p-value less than .05 were considered statistically significant for all cases. Result : In this study, the activity of the lower extremity muscle and the ratio of the vastus medial and lateral muscles according to the direction of use of the ramp were investigated. The changes in the muscle activity of the lower limbs along the direction of the ramp were significantly different between the vastus medial muscle and the peroneus longus muscle. Conclusion : For a short time on a ramp or a pedestrian crossing, a clerk in a ramp can move or stand by placing the lower limbs in various directions, but if performed in consideration of the individual's disease characteristics or unstable foot position, It is thought that there will be an effect to prevent on the ankle and knee unstability.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.4
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• pp.332-340
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• 2011

A missile with a strapdown seeker should properly estimate line-of-sight(LOS) rate using its attitude information and the look angle of the seeker because LOS rate information in an inertial coordinate system, which is used for a proportional navigation(PN) homing guidance, can not be obtained directly. However, an unnecessary feedback loop(Parasite Loop) is formed in the guidance and control loop, and it may cause the guidance performance degradation or even the unstability of the system(Parasite Effect). This paper presents estimation methods for the LOS rate information and effective ways to minimize the parasite effect using Routh-Hurwitz stability criterion. Various numerical simulations are also included to verify the proposed methods.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.255-264
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• 2009

Soils containing vanishing materials lead changes in the microstructure of particulate media due to water inflow. Thus, dissolution renders some local unstability. As the moisture contents decease, the component of the vanished materials may affects on the cementation of paniculate materials. This cementation phenomenon has a huge influence on the stiffness, strength and stability under lower stress level. The goal of this study is to introduce the cementation effects on a compressional wave velocity, a shear wave velocity, and the resonant frequency of shear waves. The glass bead and salt water with different mole contents are used. Test results show that the changes of shear and compressional wave velocities consist of three stages. In the first region, compressional wave velocities increase and shear wave velocities decrease with a decreases in reducing water contents from 100% to 90~95%. In the second region, shear and compressional wave velocities become stable at 90~95% to 10% of the water contents. In the third region, shear and compressional wave velocities increases dramatically with a decrease in the water content due to the capillary force and cementation of salt. Furthermore, the resonant frequency of the shear waves shows similar phenomenon. Specimens prepared by glass beads and salt water are proved to be able to provide a meaningful insight in under structural behaviors of the cementation.

• Journal of Korean Academy of Nursing
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• v.47 no.3
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• pp.420-430
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• 2017

Purpose: The aim of this study was to explore characteristics of and risk factors for accidental inpatient falls. Methods: Participants were classified as fallers or non-fallers based on the fall history of inpatients in a tertiary hospital in Seoul between June 2014 and May 2015. Data on falls were obtained from the fall report forms and data on risk factors were obtained from the electronic nursing records. Characteristics of fallers and non-fallers were analyzed using descriptive statistics. Risk factors for falls were identified using univariate analyses and logistic regression analysis. Results: Average length of stay prior to the fall was 21.52 days and average age of fallers was 61.37 years. Most falls occurred during the night shifts and in the bedroom and were due to sudden leg weakness during ambulation. It was found that gender, BMI, physical problems such elimination, gait, vision and hearing and medications such as sleeping pills, antiarrhythmics, vasodilators, and muscle relaxant were statistically significant factors affecting falls. Conclusion: The findings show that there are significant risk factors such as BMI and history of surgery which are not part of fall assessment tools. There are also items on fall assessment tools which are not found to be significant such as mental status, emotional unstability, dizziness, and impairment of urination. Therefore, these various risk factors should be examined in the fall risk assessments and these risk factors should be considered in the development of fall assessment tools.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.2
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• pp.18-23
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• 2016

Self-assembly of organic molecules is formed spontaneously on surfaces by electrostatic interaction with substrate. This research has shown that the self-assembly improves safety and handling tractability of high-energetic materials (HEMs). According to the recent study, control of the specific crystal size for reducing the internal defects is mightily important, because the internal defects are a factor in unstability of HEMs. In turn, we performed self-assembly of organic molecules and HEMs by using nano-sized HEMs, which were produced by drowing-out or milling/crystallization. Surface modification efficiency was decided by size distribution, zeta-potential, friction sensitivity and electrostatic charge.

• Proceedings of the KSR Conference
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• 2003.10c
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• pp.236-246
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• 2003

This paper is implemented a control algorithm in order to be stable and minimized to entire train traffic system at delayed case. Signal ing system is described wi th algebraic equations given for train headway, Discrete-event simulation principles are reviewed and a demonstration block signaling model using the technique is implemented. Train congestion at station entrance for short headway operation is demonstrated and the propagation of delays along a platform of trains from any imposed delay to the leading train is also shown. A rail way signaling system is by nature a distributed operation with event triggered at discrete intervals. Although the train kinematic variables of position, velocity, and acceleration are continually changing, the changes are triggered when the trains pass over section boundaries and arrive at signals and route switches. This paper deals with linear-mode1ing, stability and optimal control for the traffic on such metro line of the model is reconstructed in order to adapt the circuits. This paper propose optimal control laws wi th state feedback ensuring the stability of the modeled system for circuits. Simulation results show the benefit to be expected from an efficient traffic control. The main results are summarized as follows: 1. In this paper we develop a linear model describing the traffic for both loop lines, two state space equations have been analyzed. The first one is adapted to the situation where a complete nominal time schedule is available while second one is adapted when only the nominal time interval between trains is known, in both cases we show the unstability of the traffic when the proceeding train is delayed following properties, - They are easily implemented at law cost on existing lines. - They ensure the exponetial stability of loop system. 2. These control laws have been tested on a traffic simulation software taking into the non-linearites and the physical constraints on a metro line. By means of simulation, the efficiency of the proposed optimal control laws are shown.