• 전기학회논문지
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• 제67권12호
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• pp.1685-1689
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• 2018

In this research, 51% attack or majority attack is becoming an important security issue for proof of work based blockchains. Due to decentralized nature of blockchains, any attacks that shutdowns the network or which take control over the network is hard to prevent and assess. In this paper, different types of majority attack are summarized and the motivations behind the attacks are explained. To show the feasibility of the majority attack, we build an example mining machines that can take control over two of the public blockchains, Vertcoin and Monero.

• Journal of Chest Surgery
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• 제8권2호
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• pp.125-134
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• 1975

The record of 137 patients with spontaneous pneumothorax seen at Busan National University Hospital during past 3years were reviewed to study the possible pathogenesis and its effective management. and the results obtained as follows; 1] The incidence of the "spontaneous" pneumothorax which developed without underlying pathology was 13-1%. The majority of those cases was considered as the result of rupture of subpleural blebs. 2] The incidence of secondary pneumothorax which developed with underlying pathology was 50.0%, in which 42.3% was combined with pulmonary tuberculosis and 8, 0% was combined with pulmonary infection. The traumatic pneumothorax was developed in 36-5% of total series. 3] In age distribution, there was pronounced difference between spontaneous and secondary pneumothorax. The majority of spontaneous pneumothorax cases was 20-30 decade and tall and tall and thin in body structure. In secondary pneumothorax, however, the incidence was relatively high in age group more than 50 years old. 4] The incidence of pneumothorax combined with pulmonary tuberculosis was particularly high in our country, and the cause of pneumothorax was seemed due to the rupture of subpleural caseous foci in some cases, but the majority was seen due to the rupture of emphysematous blebs which were formed with a pathological process of chronic tuberculosis. 5]Closed [tube] thoracotomy was the main therapeutic approach of choice in the great majority ,of pneumothorax in our series with the relapse rate of 19.6%. However, open thoracotomy and adequate surgical procedures should be undertaken in patients with continuous air leakage over 7 days and recurrent attack of pneumothorax.

• Journal of Korean Neurosurgical Society
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• 제38권6호
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• pp.425-430
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• 2005

Objective : Recently, the survival rate and prognosis of spontaneous intracerebral hemorrhage[S-ICH] has improved, and their enhanced survival has become associated with a consequent rise in the recurrence of S-ICH. The aim of this study is to improve the prevention of recurrent S-ICH. Methods : Between January 1999 and March 2004, we experienced 48 cases of recurrence. We classified the patients into the two groups; a double ICH group and a triple ICH group. We investigated their brain CTs, MRIs, cerebral angiographies, and medical records, retrospectively. Results : Majority of patients had the intervals at least 12 months, and most of patients underwent conservative treatment. The most common hemorrhage pattern of recurrence was ganglionic-ganglionic [basal ganglia - basal ganglia], and the second attack was contralateral side of the first attack in a large percentage of all patients. Prognosis of patients was worsened in recurrent attack. Nearly all patients had medical history of hypertension, and most patients have taken antihypertensive medication at the arrival of emergency room. Conclusion : In treating hypertension for S-ICH patients, we stress that blood pressure must be thoroughly controlled over a long period of time.

• 대한물리치료과학회지
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• 제3권3호
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• pp.57-64
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• 1996

The purpose of this study is to investigate risk factor found in the patients with stroke in physical therapy. A questionnaire survey was carried out for 130 the patients, who had comparatively alert mentality, hospitalized in kyung hee oriental medical hospital with stroke from January, 1st to May 31st, 1996. Major findings of this stuty were as follows. 1. The stroke patients 67(51.5%)were males and 63(48.5%) femals. The age groups of 50 to 69 years accounted for 67.6% of the total stroke patients are the highest. The job groups of commerce and business of patients 58.5%. The living groups of major citys of the revealed the highest incidence(40.8%). 2. There were 40 patients (30.8 %) who had hemorrhage related condions as the direct cause of their stroke, and 90 patients (69.2 %) who had cerebral infarction with no hemorrhaging as the cause. of the disease that the patients suffered from before their stroke, blood pressure related problems were most numberous 76 patients(58.5%) had such problems. 3. A month before their attack of stroke, were asked what thay thought could become the causes of their strokes. The most frequently mentioned answers were fatigue, drinking too much, and smoking, as chosen by 45 patients(34.6 %). 4. In regarding the relation between stress and stroke, (37.7%), of the surveyed belonged to the most numerous group had of people who said they were not under stress. Yet this group had a large number of parents. And 22.3 % of the surveyed named conflicts among parents, siblings, and relatives. 5. Questions were asked to find out the relationship between complications of stroke and smoking or drinking. It was surprising to see a high rate of attack among the 55.4 % majority who answered that they did not smoke nor drink. 6. To sum up the affect of food on attack of stroke, 42.5% of the people who had a sprcey and salty diet had a higher rate of attack then the group of people with leisurely nature. 7. Looking at the family history, 40.4% of the patients said their parents also suffered the disease. This percentage is the highest. And 40.0% answered that there is no one who suffered in their family history. Judging from the percentages and family.

• Journal of Chest Surgery
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• 제24권5호
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• pp.451-458
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• 1991

We have observed 101 cases of recurrent spontaneous pneumothorax from Sep. 1979 to Dec. 1989 at the Department of Thoracic & Cardiovascular Surgery, College of Medicine, Inje University, Pusan Paik Hospital and the result obtained as follows. 1] Age range of patients was the first decade to seventh decade. Males outnumbered females by 6.7: l. One or two episodes of recurrent attack were noted in majority cases. 2] In distribution of the lesion sites, right side was 55 cases[55.4%], left 42 cases[41.9%], and bilateral 4 cases[3.0%]. 3] In clinical manifestations, abrupt onset of dyspnea was 78 cases[77.2%], chest pain 48 cases[47.5%], cough 9 cases[8.9%] and chest discomfort 8 cases[7.9%]. 4] Of 101 cases, 48 cases were associated with pulmonary tuberculosis and other cases were associated with subpleural bullae and blebs[26 cases], emphysema[7 cases], bronchiectasis[2 cases], lung cancer[1 case], and silicosis[1 case], 5] In 88 cases[87.2%] of patients, the magnitude of collapse was above 50% in plain chest film. 6] The interval of recurrence after last attack was frequently within 1 year. 7] In the management, closed thoracostomy with underwater-sealed drainage was applied in first recurrent 53 cases but 2nd recurrence was developed in 16 cases. In 52 cases, surgical management was applied. The pleurodesis with chemical agent[tetracycline] via chest tube was applied in 2 cases. Among 51 cases subjected to the open thoracotomy, pleural abrasion was performed in 3 cases, excision of bullae & blebs in 12 cases, wedge resection in 28 cases, lobectomy in 6 cases and wedge resection combined with lobectomy in 2 cases. In one case subjected to the median sternotomy, wedge resection on both lung apex was performed. 8] Postoperative complications were developed in 8 cases but not serious.

• 한국콘텐츠학회논문지
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• 제12권5호
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• pp.32-39
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• 2012

온라인을 통해 서비스를 제공받기 위해서는 회원가입이 필요하고, 이렇게 회원가입을 통해 수집된 개인정보는 해킹으로 인한 개인정보의 유출로 이어진다. 특히, 유출된 개인정보에 의해 사용자가 지속적으로 공격 받고 피해를 입어 심각한 사회문제가 되고 있다. 이러한 사회공학적 공격 방법은 사람의 심리를 기반으로 하기 때문에, 대부분의 경우 피해를 입기 쉽다. 이러한 공격을 막기 위해 블랙리스트를 이용하여 피싱 사이트를 차단하는 방법이 있다. 하지만 이러한 방법은 짧은 생명 주기로, 새로 생성되는 피싱 사이트에 대해서는 대처 할 수가 없다는 문제를 가지고 있다. 본 논문에서는 사용자의 개인정보 유출 사고를 최소화하는 두 가지 방안을 제시하였다. 블랙리스트와 화이트리스트 비교를 통해 사이트 신뢰를 표시하여 사용자에게 사이트의 진위여부를 판단할 수 있도록 하고, 새로 생성된 사이트에 대해서는 개인정보 입력 감지를 통하여 개인정보 유출을 사전에 차단을 하여, 사용자의 개인정보 유출 사고를 최소화 하는 방안을 제시하였다.

• 한국정보통신학회논문지
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• 제18권4호
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• pp.867-875
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• 2014

인터넷 서비스의 발전은 사용자가 언제어디서나 업무 처리가 가능한 인터넷 뱅킹 서비스를 가능하게 하였다. 하지만 인터넷을 통한 서비스 접근은 공격자에게 쉽게 사용자의 비밀정보가 노출될 수 있는 보안 취약점을 가지고 있다. 이를 방지하기 위해 현재 서비스 제공업체에서는 초기에 사용자의 아이디와 비밀번호를 이용하여 사용자를 인증하는 절차를 수행하게 된다. 하지만 현재 많은 사용자들이 짧고 단순한 비밀번호를 사용하며 주기적으로 비밀번호를 변경하지 않아 공격자의 전수 조사 공격에 의해 사용자의 비밀번호가 쉽게 노출될 수 있는 문제점을 가진다. 본 논문에서는 사용자의 비밀번호를 그대로 사용하지만 비밀번호가 지속적으로 적합한 보안 강도를 가지도록 실제 비밀번호를 보완해 주는 기법을 제안한다. 해당 기법은 추가적인 비밀정보를 이용하여 실제 비밀번호를 대체할 수 있도록 하며 주기적으로 비밀번호를 사용자의 실제 비밀번호에 대한 변경 없이 교체할 수 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권6호
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• pp.2168-2187
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• 2021

The smart grid replaces the traditional power structure with information inventiveness that contributes to a new physical structure. In such a field, malicious information injection can potentially lead to extreme results. Incorrect, FDI attacks will never be identified by typical residual techniques for false data identification. Most of the work on the detection of FDI attacks is based on the linearized power system model DC and does not detect attacks from the AC model. Also, the overwhelming majority of current FDIA recognition approaches focus on FDIA, whilst significant injection location data cannot be achieved. Building on the continuous developments in deep learning, we propose a Deep Learning based Locational Detection technique to continuously recognize the specific areas of FDIA. In the development area solver gap happiness is a False Data Detector (FDD) that incorporates a Convolutional Neural Network (CNN). The FDD is established enough to catch the fake information. As a multi-label classifier, the following CNN is utilized to evaluate the irregularity and cooccurrence dependency of power flow calculations due to the possible attacks. There are no earlier statistical assumptions in the architecture proposed, as they are "model-free." It is also "cost-accommodating" since it does not alter the current FDD framework and it is only several microseconds on a household computer during the identification procedure. We have shown that ANN-MLP, SVM-RBF, and CNN can conduct locational detection under different noise and attack circumstances through broad experience in IEEE 14, 30, 57, and 118 bus systems. Moreover, the multi-name classification method used successfully improves the precision of the present identification.

• 한국인터넷방송통신학회논문지
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• 제21권4호
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• pp.15-23
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• 2021

대부분의 해킹 과정에서는 장기간에 걸쳐 내부에 침입하고 목적 달성을 위해 우회접속을 이용한 외부와 통신을 시도한다. 고도화되고 지능화된 사이버 위협에 대응하는 연구는 주로 시그니처 기반의 탐지 및 차단 방법으로 진행되었으나, 최근에는 위협 헌팅 방법으로 확장되었다. 조직적인 해킹그룹의 공격은 장기간에 걸쳐 지능형 지속 공격이면서, 우회 원격 공격이 대부분을 차지한다. 그러나 지능화된 인지 기술을 활용한 침입 탐지 시스템에서도 기존의 침입 형태에만 탐지성능을 발휘할 뿐이다. 따라서, 표적형 우회 원격 공격에 대한 대응은 기존의 탐지 방법과 위협 헌팅 방법으로도 여전히 한계점이 있다. 본 논문에서는 이러한 한계점을 극복하기 위해 조직적인 해킹그룹의 표적형 우회 원격 공격 위협을 탐지할 수 있는 모델을 제안한다. 이 모델은 우회 원격 접속자의 원점 IP 확인 방법을 적용한 위협 헌팅 절차를 설계하였고, 실제 국방 정보체계 환경에서 제안한 방법을 구현하여 유효성을 검증하였다.

• 정보보호학회논문지
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• 제34권3호
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• pp.431-437
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• 2024

최근 드론은 공공의 목적을 넘어, 다양한 산업에서 활용되며, 민간 분야까지 확대되어 상용화되는 실정이다. 현재 상용화되는 대부분 드론은 사용자에게 드론의 위치를 알리기 위한 목적으로, 인공위성으로부터 위치 신호를 수신하는 GPS 수신기를 장착하지만, 인공위성으로부터 위치 신호를 전달받는 거리가 멀다는 단점과 이로 인하여 수신하는 위치 신호의 세기가 약하다는 단점이 존재한다. 이러한 단점들로 인하여, 인공위성으로부터 수신하는 위치 신호보다 더욱 강한 신호를 드론에서 수신한다면, 의도하지 않은 위치정보를 수신하는 위치 조작과 재밍 공격이 가능하다. 따라서, 본 논문에서는 GPS를 기반으로 위치정보를 활용하는 드론에 대한 안전성 평가 및 무선 통신 상황에서 발생 가능한 취약점에 대응하기 위한 목적으로, 상용 드론들을 대상으로, GPS 스푸핑 공격에 대한 가능성을 분석하고 실증한다. 본 논문의 결과는 더욱 현실적인 취약점 분석 및 안전성 평가를 위한 실험과 그 결과를 도출하기 위한 선행 연구로 활용될 것으로 사료된다.