• Journal of Chest Surgery
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• v.29 no.11
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• pp.1267-1269
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• 1996

Coronary artery bypass grafting without cardiopulmonary bypass is now one of accepted technique of myocardial revascularization. This technique is an alternative method for patients with lesions in the left anterior descending coronary artery and right coronary artery. We report a case of coronary artery bypass grafting without cardiopulmonary bypass or cardiac arrest.

• Journal of Chest Surgery
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• v.42 no.4
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• pp.532-536
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• 2009

Bypass surgery is performed for insuring continuity of a blood supply that is restricted due to obstruction of the native blood supply. Two types of surgery are commonly carried out: one is anatomic bypass and the other is extraanatomic bypass. Especially, extraanatomic bypass surgery is performed in patients who are a high risk for performing anatomical bypass surgery. The risk factors for anatomical bypass surgery are old age, infection, previous surgery and trauma. A 96-year-old patient underwent extraanatomic bypass surgery from the right femoral artery to the left femoral artery due to total occlusion of the left iliac artery, and 7 years after that operation, a pseudoaneurysm abruptly and spontaneously appeared from the bypass suture site without any predisposing factor. The lesion was revealed to be an organizing thrombus.

• Journal of Chest Surgery
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• v.35 no.5
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• pp.365-368
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• 2002

Background: Coronary artery bypass grafting(CABG) imposes large amount of medical costs, which are greatly affected by the surgical approach, quality of perioperative care and associated co-morbidities. Recently, off-pump CABG(OPCAB) has been introduced and performed with increasing frequency. To evaluate the efficacy of OPCAB in view of financial impact, we analyzed the costs and medical resources of OPCAB and compared with conventional CABG. Material and Method: From January 1998 to July 1999, 184 patients underwent CABG operation; 111 patients with OPCAB(group I) and 73 patients with conventional CABG(group II). We prospectively collected clinical data including risk factors and retrospectively reviewed the hospital resources. Result: Preoperative parameters including risk factors, postoperative mortality, morbidity and length of hospital stay were not different between the two groups, Duration of stay in the intensive care unit(ICU) (51.3 vs 128.3 hours, p<0.01) and ventilator, support time(14.9 vs 56.2 hours, p<0.01) were significantly shorter in the OPCAB group. Total hospital coats were 17,220,000 add 21,250,000(Korean Won) in group I and II, respectively(p<0.01). There were significant differences in operation fee, costs for operative materials, transfusion and diagnostic radiology between two groups. In group I, all the resources except diagnostic radiology were significantly decreased compared with group II. Conclusion: OPCAB has a beneficial effect on hospital charge and resource utilization. Shorter duration of the ICU stay and ventilatory support time may reduce the total hospital costs.

• Journal of the Korean Association of Geographic Information Studies
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• v.7 no.1
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• pp.84-93
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• 2004

Recently, domain-specific demands with respect to practical applications and analysis scheme using spatial thematic information are increasing. Accordingly, in this study, GIS-based application program is implemented to perform spatial analysis in transportation geography with base road layer data. Using this program, quantitative estimation of circuity and accessibility, which can be extracted from nodes composed of the graph-typed network structure, in a arbitrary analysis zone or administrative boundary zone is possible. Circuity is a concept to represent the difference extent between actual nodes and fully connected nodes in the analysis zone. While, accessibility can be used to find out extent of accessibility or connectivity between all nodes contained in the analysis zone, judging from inter-connecting status of the whole nodes. In put data of this program, which was implemented in AVX executable extension using AvenueTM of ArcView, is not transportation database information based on transportation data model, but layer data, directly obtaining from digital map sets. It is thought that computation of circuity and accessibility can be used as kinds of spatial analysis functions for GIS applications in the transportation field.

• Journal of Chest Surgery
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• v.38 no.11 s.256
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• pp.733-738
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• 2005

Background: The possibility of incomplete revascularization and development of flow competition after revascularization of the borderline lesion made the hybrid strategy as an option for complete revascularization. Material and Method: From January f998 to July 2004, 25 $(3.2\%)$ patients underwent hybrid revascularization among 782 total OPCAB procedures. Clinical results and angiographic patencies were evalulated. Percutaneous coronary intervention (PCI) was peformed before CABG in 8 patients and after CABG in 47 patients. Result: The causes of PCIs before CABG were to achieve complete revascularization with minimally invasive surgery (n=7) and emergent PCI for culprit lesion (n=1). The indications of PCIs after CABG were high possibility of flow competition in the borderline lesion of right coronary artery territory (n=8), diffuse atheromatous lesion preventing anastomosis of graft (n=5), severe calcified ascending aorta with no more arterial grafi available (n=3), and intramyocardial coronary lesion (n=1). Mean number of distal anastomoses was $2.3\pm1.0$. Mean number of lesions treated by PCI was $1.2\pm0.4$. There was no operative or procedure-related mortality. PCI-related complication was periprocedural myocardial infarction in one patient, and complications related to CABG were transient atrial fibrillation (n=5), perioperative myocardial infarction (n=1), and transient renal dysfunction (n=1). Early postoperative coronary angiography $(1.8{pm}1.6days)$ revealed $100\%$ patency rate of grafts (57/57). The stenosis occurred in one patient performed PCI before CABG, which was successfully treated with re-ballooning. During midterm follow-up (mean; $25{\pm}26$ months), 1 patient died of congestive heart failure. All survivors (n=24) accomplished follow-up coronary angiographics, which showed .all grafts (56/57) were patent except one string sign. In-stent restenosis was developed in 2 patients who received bare metal stents. Conclusion: In selected patients, complete revascularization was achieved with low risk by taking the hybrid strategy.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.3
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• pp.31-41
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• 2016

Damage to structures, such as bridge piers, are increasing rapidly due to the debris moving along rivers at the time of flooding. Therefore, the debris fin, debris deflector and debris sweeper, which are debris reduction systems, were produced in this study and an accumulation experiment was carried out on the experimental channel according to the existence of the reduction system. The debris fin is the reduction system that creates parallel flow on debris accumulated on the bridge to pass through the bridge, which was produced using wood. In addition, the debris deflector was produced using steel pipes and it has the type of detouring the direction of debris. The debris sweeper passes the debris using the magnetic force rotation of a screw-shaped cylindrical structure by water flow and it was produced using acrylic material. The experiment was carried out by analyzing the level of accumulation according to the hardness and dropping method of the debris and comparing the accumulation rate of reduction systems, and the experiment was carried out 5 times. According to the experimental results, there was a difference in the accumulation rate according to the type of reduction system and the shape of debris, and it often depended significantly on the initial shape of debris accumulation. The direct debris reduction effect on the bridge was higher in the order of the debris deflector, debris sweeper and debris fin, but in case of the debris deflector, damage, such as stream turbulence, changes in water level and river bed, and the loss of deflector can occur due to debris accumulated directly on the debris deflector. Therefore, it is necessary to design the debris deflector considering these issues.

• The KIPS Transactions:PartC
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• v.10C no.4
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• pp.447-454
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• 2003

Optical burst switching (OBS) has been proposed to reduce the use of fiber delay lines (FDLs) and to realize the optical switching paradigm of the next-generation ail optical networks. The OBS can provide improvements over wavelength routing in terms of bandwidth efficiency and core network scalability via statistical multiplexing of bursts. Recently, another challenging issue is how to upport quality of service (QoS) in the optical burst switching networks. In this paper, we propose a deflection routing scheme to guarantee the QoS for the OBS networks to detour lower priority burst forward to the deflection routing path when congested. A big advantage of the proposed scheme is the simplicity of QoS provision, that comes from the simple QoS provisioning algorithm. Also, the QoS provisioning scheme be able to make efficient networks by fairly traffic distributing with the reduce of the use of FDLs at core routers. The QoS provisioning scheme has been verified to reliably guarantee the QoS of priority 0, 1, 2 burst and to efficiently utilize network resources by computer simulations using OPNET As results, the end-to-end delay of high priority burst is improved, and the network efficiency is also improved.

• Journal of Korean Society of Transportation
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• v.22 no.4 s.75
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• pp.43-56
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• 2004

The KHCM procedure is a micro level analysis at signalized intersections requiring a lot of input variables and complex computations. The research was to investigate the possibility of simplifying the analysis procedures by using the generalized or the combined variables that less influence on the adjusted traffic volume and through-car equivalents of left or right turns. It was also tried to make lane grouping into directional flow ratio(v/s) based on a field surveys. The maximum and minimum values of each variables were compared with each other through the KHCM analysis procedures in terms of control delay. The lane grouping and the synthetical influence of a simplified method was evaluated with the scenario built in prevailing maximum and minimum conditions. The study showed that the control delay was not significantly sensitive to the selected variables and the lane grouping and their synthetical influence as well.

• Proceedings of the Korean Society of Computer Information Conference
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• 2014.07a
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• pp.369-370
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• 2014

본 논문에서는 안드로이드 환경에서 클래스 반사(Reflection)과 예외처리를 이용하여 안드로이드 보호 시스템을 우회하여 임의의 코드를 수행할 수 있는 방법을 제시한다. 일반적인 자바 환경과는 달리 안드로이드 환경에서는 보안 강화를 위해 APK 파일 내 루트 디렉토리의 클래스 파일만을 반사를 통해 동적 로딩이 가능하다. 하지만, 본 논문에서는 클래스 반사와 예외 처리를 이용하여 임의의 디렉토리 내 파일을 로딩 및 동적 실행할 수 있는 방법을 보이며 이 방법은 저자가 알기로는 기존에 알려지지 않은 방법이다. 이를 기반으로, 본 논문에서는 AES 암호와 동적 로딩을 이용하여, 모바일 어플리케이션의 내부 코드를 은폐하는 기법을 제안한다. 제안기법을 활용 시, 첫째 공격자의 입장에서는 내부 코드를 은폐하여 백신을 우회하는 악성코드 제작이 가능하고, 둘째, 프로그램 제작자의 입장에서는 핵심 알고리즘을 은폐하여 저작권을 보호하는 코드 제작이 가능하다. 안드로이드 버전 4.4.2(Kitkat)에서 프로토타입을 구현하여 제안 기법의 실효성을 보였다.

• Journal of Chest Surgery
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• v.41 no.2
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• pp.202-209
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• 2008

Background: The introduction of Drug Eluting Stents (DES) decreased the number of patients referred for coronary artery bypass grafting (CABG). The impact of DES on CABG (Step 1) was studied and compared with the 1-year outcome after CABG with DES (Step 2). Material and Method: Surgical results for patients who underwent off-pump CABG (OPCAB) before the introduction of DES(n=298) were compared with those who underwent OPCAB after the introduction of DES (n=288) (Step 1). Postoperative 30-day and 1-year results were also compared between the patients who underwent percutaneous coronary intervention (PCI) using DES (n=220) and those who underwent OPCAB (n=255) (Step 2). Result: Since the introduction of DES, the ratio of CABG versus PCI decreased. In the CABG group, the number of high risk patients such as elderly patients (age 62 vs. 64, p=0.023), those with chronic renal failure (4% vs. 9%, p=0.021), calcification of the ascending aorta (9% vs. 15%, p=0.043), or frequency of urgent or emergent operations (12% vs. 22%, p=0.002) increased. However, there were no differences in the cardiac death and graft patency rates between the two groups (step 1). During the one-year follow up period, the rate of target vessel revascularization (12.3% vs. 2.4%, p<0.001) and major adverse cardiac events (MACE: death, myocardial infarct, TVR) were higher in the DES than the CABG group (13.6% vs 4.3%) (stage 2). Conclusion: Introduction of DES decreased the number of patients referred for surgery, and increased the comorbidity in patients who underwent CABG. DES increased the rate of target vessel revascularization, and the occurrence of MACE during the 1-year follow-up. However, there was no difference in the incidence of myocardial infarction and cardiac death between the two groups.