Earticle

하나의 서버 시스템에 여러 운영체제를 사용하거나 사용자간 메모리를 공유하는 클라우드 환경에서 공격자는 캐시 부채널 공격을 통해 비밀 정보를 유출할 수 있다. 본 논문에서는 국내 표준 블록 암호 알고리즘인 ARIA를 사전 연산 테이블 기반 최적화 기법을 이용해 구현할 경우, 캐시 부채널 공격의 일종인 Flush+Reload 공격이 적용되는 것을 확인하였다. ARIA-128을 대상으로 한 Ubuntu 환경에서의 실험 결과, Flush+Reload 공격을 통해 16바이트의 마지막 라운드 키를 찾을 수 있었으며 나아가 마지막 라운드 키와 첫 번째 라운드 키를 이용하면 마스터 키를 찾을 수 있음을 증명하였다.

Since the server system in the cloud environments can simultaneously operate multiple OS and commonly share the memory space between users, an adversary can recover some secret information using cache side-channel attacks. In this paper, the Flush+Reload attack, a kind of cache side-channel attacks, is applied to the optimized precomputation table implementation of Korea block cipher standard ARIA. As an experimental result of attack on ARIA-128 implemented in Ubuntu environment, we show that the adversary can extract the 16 bytes last round key through Flush+Reload attack. Furthermore, the master key of ARIA can be revealed from last and first round key used in an encryption processing.

Menopausal hot flushes (HFs), which manifest as a transient increase in skin temperature, occur most frequently in postmenopausal women, and sometimes negatively influence daily life. We investigated the effect of an aqueous extract of Cynanchum wilfordii (CWW) in a rat model of menopausal HFs, where tail skin temperature (TST) is increased after the rapid estrogen decline induced by ovariectomy. Ten-week-old female rats were ovariectomized and treated with CWW for 1 week. We measured TST and rectal temperatures (RT) and investigated serum estradiol. The TST in ovariectomized (OVX) rats was significantly elevated after ovariectomy compared with control rats, whereas the RT in OVX rats was not elevated. Administration of CWW (200 mg/kg/d for 7 days, p.o.) significantly improved the skin temperature increase in OVX rats. The lower level of serum estradiol in OVX rats was significantly increased by supplying E2, but it was not affected by CWW. The present study indicates a need for future research involving treatment with high concentrations of C. wilfordii and measurement over 24 h.

운전시간이 경과함에 따라 공극폐색 문제로 인하여 수직 흐름형 습지의 기능은 저하되는데 이와 같은 문제는 폰딩(ponding) 이나 월류 현상에 의하여 쉽게 관측할 수 있다. 공극폐색 잠재성을 조사하기 위하여 도로주변에 설치된 파일럿 규모의 습지 운전자료를 분석하였다. 습지에는 각각 우드칩과 마사(부석), 그리고 화산석을 충진하였다. 약 7개월 동안 도로 강우유출수 처리시험을 수행한 후 충진된 여재를 비운 후 여재 층별로 분류하여 여재에 의해 포획된 고형물 입자의 양과 특성을 분석하였다. 분석결과 대부분의 포획물질은 외부기인 부유물질 이었으며 다음으로 여재표면에 증식한 생물막인 것으로 나타났다. 특히 다른 여재와 비교하여 유기성 여재인 우드칩에서 생물막의 증식이 왕성하였다. 또한 전체 포획량 중 30% 이상이 상부 20cm 이내에 집중되어 있어 폐색으로 인한 폰딩 발생시 이 부분의 여재를 우선적으로 교체하여야 할 것으로 판단된다. 또한 모델계산 결과 우드칩 충진 습지에서 폐색에 도달하는데 약 2달 정도가 소요될 것으로 산출되었으나 실제로는 전혀 폐색 기미는 발생하지 않았는데 이는 강우시에만 운영되는 특성상 강우활동이 없는 무강우 기간 동안 포획된 유기물질이나 생물막이 자연적으로 분해되어 일정기간이 경과되면 공극이 회복되었다.

The function of vertical subsurface flow wetlands can potentially be reduced with time due to clogging and are often assumed to be occurring when ponding and overflow is observed during rainfall. To investigate their clogging potential, three pilot-scale vertical subsurface flow (VSF) wetland systems were constructed employing woodchip, pumice, and volcanic gravel as main media. The systems received stormwater runoff from a highway bridge for seven months, after which the media were taken out and divided into layers to determine the amount and characteristics of the accumulated clogging matters. Findings revealed that the main clogging mechanism was the deposition of suspended solids. This is followed by the growth of biofilm in the media which is more evident in the wetland employing woodchip. Up to more than 30% of the clogging matter were found in the upper 20 cm of the media suggesting that this layer will need replacement once clogging occurs. Moreover, no signs of clogging were observed in all the wetlands during the operation period even though an estimation of at least 2 months without clogging was calculated. This was attributed to the intermittent loading mode of operation that gave way for the decomposition of organic matters during the resting period and potentially restored the pore volume.

The central seam, the vertical 'line' between doors, in the front view of a refrigerator must have its gap and flush within certain ranges to meet functional and aesthetic requirements. The conventional criteria for gap and flush control in the industry are to keep the gap and flush within certain ranges at each of various points along the seam. For aesthetics, however, the uniformity of the gap is also as important because a 'tapered' seam is negatively perceived by human eyes. This paper shows a case study of tolerance design for a refrigerator door system. It presents a step-by-step procedure, which consists of datum flow chain analysis, identification of assembly features, computer modeling of feature tolerances, assembly operations and measurements, tolerance simulation, and tolerance adjustments based on the simulation results. It is found that extra care may need to be used to satisfy the aesthetical criterion for gap uniformity.

본 연구에서는 방사형 흐름을 가지는 지표 유출수에 대한 오염물질의 초기세척현상 모의를 통하여 주차장과 같은 소규모 불투수 배수구역에서 발생하는 수렴형 강우유출수의 동적 유출특성에 대한 일반적 특성을 고찰하고, 이를 토대로비점오염저감시설의 초기우수처리 효과를 극대화 시킬 수 있는 집수시설 배치 방안을 제시하고자 하였다. 이를 위하여1차원 확산파 방정식(diffusion wave equation)과 오염물질 운송방정식을 이용하여 이상적인 방사형 불투수 배수구역에 대한 초기세척현상을 모의 하고, 이 결과를 이용하여 배수구역의 크기에 따른 오염물질의 초기세척강도를 산정 비교하였다. 초기세척 모의결과, 생화학적 산소요구량의 경우 평균경사도 0.02에서 배수구역의 길이 30-50m 범위일 때초기세척강도가 가장 높았다. 이러한 결과는 주차장과 같은 소규모 불투수 구역에서는 강우유출수 집수시설의 위치와갯수를 조정함으로써 배수구역의 길이 변경이 가능하며 이를 통하여 초기세척 강도와 첨두부하를 인위적으로 조절 가능함을 시사한다. 특히 초기우수수 처리에 중점을 둘 경우 집수시설의 위치와 갯수를 적절히 조절하여 초기세척 강도를상승시킴으로써 동일한 용량의 비점오염저감시설로 보다 많은 오염물질 부하저감을 기대할 수 있을 것으로 판단된다.

In this study, general characteristics of dynamic behavior of stormwater runoff from a small impervious catchment was investigated from a series of simulations for a radial type surface runoff. Based on the simulation results, a better placement strategy for stormwater inlets to improve performance of a structural best management practice (BMP) was suggested. The degree of pollutant first flush from an ideal radial type impervious catchment was simulated using a 1-D diffusion wave equation coupled with a pollutant transport equation. The results showed that the first flush of the chemical oxygen demand was the strongest when the catchment length ranged 30-50m at a bed slope of 0.02. This result suggested that a required degree of the first flush can be intentionally obtained by just changing the locations and numbers of stormwater inlets, and thereby adjusting the catchment length. Particularly, the overall performance of a structural BMP in reducing pollutant load can be improved by placing the stormwater inlets at locations for obtaining a required first flush strength.

Five varieties of mushrooms, including Sae-do, were examined using farm field tests to determine their morphological characteristics and quality by performing harvest flush. Considering the cultivation characteristics of the varieties studied, the parts related to mushroom generation and production showed almost similar characteristics. Overall, the mycelial forces were similar; however, in the evaluation of plantation tests performed by farmers, "saedo" was found to be the strongest and "saehan" was considered to be the weakest. Weights of fruiting bodies were related more for compost status and regimen of use than for breeding, and it was difficult to distinguish between the weights of fruiting bodies of the varieties studied. Regardless of the variety, pileus diameter, pileus thickness, and stem length of Dalseong-gun, Yongin-si, and Boryeong-si decreased as the harvest flush progressed. However, stem thickness tended to increase in the second and third flush compared to that in the first flush, regardless of the variety. However, the Gyeongju-si farms could not identify any trends attributable to varieties and harvest flushes. The pileus size and stem length of the fruiting bodies of varieties from Buyeo farms decreased with the progression of the harvest flush. However, pileus thickness and stem thickness did not show any specific tendency of growth among the varieties studied. The differences in the morphological characteristics of mushroom varieties in each harvest cycle are expected to be caused by differences in the supply of nutrients in the medium, the quality of the compost used, and the cultivation environment rather than the variety.

The purpose of this study was investigated to runoff characteristics and unit pollutant load of nonpoint source of first runoff from road during storm event. Road runoff generally contains significant loads of micro-particles, heavy metals and organic constituents. There were two major objectives of this study. The first objective was to characterize pattern of road runoff. The second objective was to estimate of the unit pollutants load from the road first runoff. First flush runoff for four storm events was monitored on three sites of road areas in Daejeon along with traffic volume. The quantity of road runoff and quality constituents, including chemical oxygen demand(CODcr), sus-pended solids(SS), biological oxygen demand(BOD5), total nitrogen(T-N), total phosphorus (T-P), heavy metals were analyzed. The results showed that the event mean concentration(EMC) of BOD5, CODcr, SS, T-N, T-P, Fe, Cu, Cr, Zn, Pb average rages were 66 mg/L, 272 mg/L, 263 mg/L, 13.77 mg/L, 0.52 mg/L, 8.937 mg/L, 0.130 mg/L, 0.113 mg/L, 0.616 mg/L, 0.171 mg/L, respectively. The average unit pollutants load for first runoff from road BOD5, CODcr, SS, T-N, T-P, Fe, Cu, Cr, Zn, Pb were 102, 298, 552, 23.4, 0.77, 17.24, 0.47, 0.09, 1.18, 0.58 g/a/day, and 1.243, 3.685, 3.282, 0.180, 0.009, 0.115, 0.002, 0.002, 0.010, 0.0035 g/a/mm, respectively.

본 연구는 도시지역 강우유출수의 수질특성을 종합적으로 분석하고, 초기강우와 초기강우 이후 유출수의 농도차이를 정량화하여 대규모 지하저류조 설계에 필요한 유입수 수질범위를 제시하고자 수행되었다. 이를 위해 국내외 문헌 28편을 분석하여 토지이용별(도로, 주차장, 교량) EMC 특성과 초기강우(0–30분) 및 이후 구간의 오염물질 농도범위를 비교하였다. 분석결과, 초기강우 구간에서는 전체 오염부하의 50~80%가 집중되며 TSS, COD, TN, TP뿐 아니라 Zn, Cu, Pb 등 중금속이 급격히 증가하는 강한 초기강우현상이 확인되었다. 반면 초기강우 이후 유출수는 상대적으로 안정된 범위를 보였으나 여전히 높은 오염물질 농도를 보였다. 따라서, 대규모 지하저류조의 평균 설계농도는 TSS 30–150mg/L, COD 25–80mg/L, TN 2–6mg/L, TP 0.20–0.80mg/L, Zn 0.10–0.30mg/L로 산정되었다. 또한 하수도법, 물환경보전법, 환경정책기본법, 물순환촉진법 등 국내 법체계 및 미국·일본·독일의 사례 검토를 통하여 대규모 지하저류조는 단순 치수시설이 아닌 수질관리시설로 기능해야 함을 확인하였다. 본 연구결과는 도시침수 대응과 수질보전을 동시에 달성하기 위한 지하저류조 설계·운영의 기초자료로 활용될 수 있다.

This research analyzed the water quality characteristics of urban stormwater runoff and quantified the differences in pollutant concentrations between the first flush and the post–first flush period, with the aim of presenting appropriate influent water quality ranges for designing large-scale underground storage facility. The analysis revealed that 50–80% of the total pollutant load occurred during the first flush, with high increases in TSS, COD, TN, TP, and heavy metals such as Zn, Cu, and Pb. In contrast, pollutant concentrations in the post–first flush period stabilized but still remained relatively high concentrations. The average design influent concentrations for large underground storage facilities were estimated as TSS 30–150mg/L, COD 25–80mg/L, TN 2–6mg/L, TP 0.20–0.80mg/L, and Zn 0.10–0.30mg/L. In addition, a review of Korean legislation and U.S., Japanese, and German case studies confirmed that large-scale underground storage facilities should serve not only for flood control but also as water quality management infrastructure. The findings of this study provide basic data for the design and operation of underground storage facilities aimed at simultaneously reducing urban flooding and improving water quality.

본 연구는 도시지역 강우유출수의 수질특성을 종합적으로 분석하고, 초기강우와 초기강우 이후 유출수의 농도차이를 정량화하여 대규모 지하저류조 설계에 필요한 유입수 수질범위를 제시하고자 수행되었다. 이를 위해 국내외 문헌 28편을 분석하여 토지이용별(도로, 주차장, 교량) EMC 특성과 초기강우(0–30분) 및 이후 구간의 오염물질 농도범위를 비교하였다. 분석결과, 초기강우 구간에서는 전체 오염부하의 50~80%가 집중되며 TSS, COD, TN, TP뿐 아니라 Zn, Cu, Pb 등 중금속이 급격히 증가하는 강한 초기강우현상이 확인되었다. 반면 초기강우 이후 유출수는 상대적으로 안정된 범위를 보였으나 여전히 높은 오염물질 농도를 보였다. 따라서, 대규모 지하저류조의 평균 설계농도는 TSS 30–150mg/L, COD 25–80mg/L, TN 2–6mg/L, TP 0.20–0.80mg/L, Zn 0.10–0.30mg/L로 산정되었다. 또한 하수도법, 물환경보전법, 환경정책기본법, 물순환촉진법 등 국내 법체계 및 미국·일본·독일의 사례 검토를 통하여 대규모 지하저류조는 단순 치수시설이 아닌 수질관리시설로 기능해야 함을 확인하였다. 본 연구결과는 도시침수 대응과 수질보전을 동시에 달성하기 위한 지하저류조 설계·운영의 기초자료로 활용될 수 있다.

This research analyzed the water quality characteristics of urban stormwater runoff and quantified the differences in pollutant concentrations between the first flush and the post–first flush period, with the aim of presenting appropriate influent water quality ranges for designing large-scale underground storage facility. The analysis revealed that 50–80% of the total pollutant load occurred during the first flush, with high increases in TSS, COD, TN, TP, and heavy metals such as Zn, Cu, and Pb. In contrast, pollutant concentrations in the post–first flush period stabilized but still remained relatively high concentrations. The average design influent concentrations for large underground storage facilities were estimated as TSS 30–150mg/L, COD 25–80mg/L, TN 2–6mg/L, TP 0.20–0.80mg/L, and Zn 0.10–0.30mg/L. In addition, a review of Korean legislation and U.S., Japanese, and German case studies confirmed that large-scale underground storage facilities should serve not only for flood control but also as water quality management infrastructure. The findings of this study provide basic data for the design and operation of underground storage facilities aimed at simultaneously reducing urban flooding and improving water quality.

Avena sativa, known as oat, has been reported to improve the moisture levels of facial skin. However, effects of Avena sativa on pigmentation and facial flush have not been investigated. This study verify the efficacy of a cream containing Avena sativa extracts on skin pigmentation and facial flush. This clinical efficacy experiment employed 10 females above the age of 35 selected a randomized and double-blind clinical trial. They were instructed to use a cream containing oats extracts as a major ingredient on one side of their face and a cream without oats on the other side. A Robo Skin Analyzer (CS50, Inforward Inc, Japan) was employed to identify the impact of the oats cream on the pigmentation and hot flush of their facial skin. The experiment was conducted for 4 weeks after use of the two creams. the pigmentation located on the side affected by oats extract had lightened by 38.21% after 4 weeks and the hot flush decreased by 65.97% after 4 weeks use. In addition, throughout the duration of the experiment, side effects such as erythema, edema, scaling, itching, stinging, burning, tightness, and prickling were not observed. These results manifested Avena sativa extracts affect to reduce human facial pigmentation and flush, introducing as a cosmetic ingredient.

DIn this study, total 12 participants who are early 20`s womens in technical college and also had a skin complaint such as cutaneous erythema and sensitivity. Methodologically, the 12 participants were divided into group A and B. Group A was clinically treated with moisturizing pack applied on their face after vitamin C ionophoresis, while group B were treated only with vitamin C ionophoresis. For measurement, potential effects of vitamin C ionophoresis on erythema were subjectively assessed along with measurement of oil/moisture content and visual assessment. According to the subjective assessment, this study came to a conclusion that most of subjects generally showed alleviation in their symptoms of erythema. According to measurement of oil/ moisture content, both group A and B showed higher moisture content after clinical experiment than before, but didn’t show any significant variation in oil content after experiment. This finding indicated that moisturizing pack didn’t have any significant effects on oil content, but vitamin C ionophoresis was effective in increasing moisture content of skin.

Flush inlet, which has been chosen for modem air vehicles to take advantage of structure compactness and small RCS, gives rise to some aerodynamic problems such as flow separation and distortion due to vortices which deteriorate the performance of both inlet and engine. In this study, pressure recoveries at inlet exit plane were evaluated through numerical analyses of 3D turbulent flow for various inlet shapes and flight conditions. Inlet shape was controlled by changing ramp angle and width of throat, and effects of mass flow rate and angle of attack were investigated.

파일 시스템 버퍼 캐시는 느린 스토리지의 접근 횟수를 줄여 입출력 성능 향상에 기여하지만, 캐시에서 수정된 데이터를 스토리지에 오랫동안 반영하지 않을 경우 크래쉬 발생 시 최신 데이터가 유실되거나 데이터의 일관성이 깨어지는 문제가 발생할 수 있다. 이를 방지하기 위해 대부분의 운영체제는 수정 데이터를 주기적으로 스토리지에 반영하는 flush 데몬을 사용한다. 본 논문은 파일시스템의 쓰기 연산 중 30-70%가 주기적인 flush에 의해 발생함을 분석하고, 이를 소량의 NVRAM 버퍼 캐시를 이용하여 해결하는 기법을 제시한다. 특히, 본 논문은 델타 쓰기 및 그룹 기반 교체 기법을 제안하여 소량의 NVRAM 만으로 스토리지 쓰기 트래픽과 처리량을 각각 44.3%와 23.6% 개선할 수 있음을 보인다.

File I/O buffer cache plays an important role in narrowing the wide speed gap between the main memory and the secondary storage. However, data loss or inconsistencies may occur if the system crashes before the data that has been updated in the buffer cache is flushed to storage. Thus, most operating systems adopt a daemon that periodically flushes dirty data to the secondary storage. In this study, we show that periodic flushes account for 30-70% of the total write traffic to storage and remove this inefficiency by implementing a small, non-volatile buffer cache. Specifically, we present space-efficient management techniques, such as delta-write and fragment-grouping, and show that the storage write traffic and throughput can be improved by a margin of 44.2% and 23.6%, respectively, with only a small NVRAM.

캐시 부채널 공격 중 하나인 FLUSH+RELOAD 공격은 높은 해상도와 적은 노이즈로 여러 악성 프로그램에서도 활용되는 등 비밀 정보의 유출에 대한 위험성이 높은 공격이다. 따라서 이 공격을 막기 위해 실시간으로 공격을 탐지하는 기술을 개발할 필요가 있다. 본 논문에서는 프로세서의 PCM (Performance Counter Monitor)를 이용한 실시간 FLUSH+RELOAD 공격 탐지 기법을 제안한다. 탐지 방법의 개발을 위해 우선 공격이 발생하는 동안 PCM의 여러 카운터들의 값들의 변화를 4가지 실험을 통해 관찰하였다. 그 결과, 3가지 중요한 요인에 의해 공격 탐지를 할 수 있다는 것을 발견하였다. 이를 바탕으로 머신 러닝의 logistic regression과 ANN(Artificial Neural Network)를 사용해 결과에 대한 각각 학습을 시킨 뒤 실시간으로 공격에 대한 탐지를 할 수 있는 알고리즘을 개발하였다. 이 탐지 알고리즘은 일정한 시간동안 공격을 진행하여 모든 공격을 감지하는데 성공하였고 상대적으로 적은 오탐률을 보여주었다.

FLUSH+RELOAD attack exposes the most serious security threat among cache side channel attacks due to its high resolution and low noise. This attack is exploited by a variety of malicious programs that attempt to leak sensitive information. In order to prevent such information leakage, it is necessary to detect FLUSH+RELOAD attack in real time. In this paper, we propose a novel run-time detection technique for FLUSH+RELOAD attack by utilizing PCM (Performance Counter Monitor) of processors. For this, we conducted four kinds of experiments to observe the variation of each counter value of PCM during the execution of the attack. As a result, we found that it is possible to detect the attack by exploiting three kinds of important factors. Then, we constructed a detection algorithm based on the experimental results. Our algorithm utilizes machine learning techniques including a logistic regression and ANN(Artificial Neural Network) to learn from different execution environments. Evaluation shows that the algorithm successfully detects all kinds of attacks with relatively low false rate.

캐시 부채널 공격 중 하나인 FLUSH+RELOAD 공격은 높은 해상도와 적은 오류로 그 위험성이 높고, 여러가지 프로그램에서도 적용되어 개인정보의 유출에 대한 위험성까지 증명 되었다. 따라서 이 공격을 막기 위해 실시간으로 감지 할 수 있어야 할 필요성이 있다. 본 연구에서는 4가지 실험을 통하여 이 FLUSH+RELOAD 공격을 받을 때 PCM(Performance Counter Monitor)를 사용해 각각의 counter들의 값의 변화를 관찰하여 3가지 중요한 요인에 의해 공격 탐지를 할 수 있다는 것을 발견하였다. 이를 이용하여 머신 러닝의 logistic regression과 ANN(Artificial Neural Network)를 사용해 결과에 대한 각각 학습을 시킨 뒤, 실시간으로 공격에 대한 탐지를 할 수 있는 프로그램을 제작하였다. 일정한 시간동안 공격을 진행하여 모든 공격을 감지하는데 성공하였고, 상대적으로 적은 오탐률을 보여주었다.

캐시 부채널 공격 중 하나인 FLUSH+RELOAD 공격은 높은 해상도와 적은 오류로 그 위험성이 높고, 여러가지 프로그램에서도 적용되어 개인정보의 유출에 대한 위험성까지 증명 되었다. 따라서 이 공격을 막기 위해 실시간으로 감지 할 수 있어야 할 필요성이 있다. 본 연구에서는 4가지 실험을 통하여 이 FLUSH+RELOAD 공격을 받을 때 PCM(Performance Counter Monitor)를 사용해 각각의 counter들의 값의 변화를 관찰하여 3가지 중요한 요인에 의해 공격 탐지를 할 수 있다는 것을 발견하였다. 이를 이용하여 머신 러닝의 logistic regression과 ANN(Artificial Neural Network)를 사용해 결과에 대한 각각 학습을 시킨 뒤, 실시간으로 공격에 대한 탐지를 할 수 있는 프로그램을 제작하였다. 일정한 시간동안 공격을 진행하여 모든 공격을 감지하는데 성공하였고, 상대적으로 적은 오탐률을 보여주었다.

캐시 부채널 공격 중 하나인 FLUSH+RELOAD 공격은 높은 해상도와 적은 노이즈로 여러 악성 프로그램에서도 활용되는 등 비밀 정보의 유출에 대한 위험성이 높은 공격이다. 따라서 이 공격을 막기 위해 실시간으로 공격을 탐지하는 기술을 개발할 필요가 있다. 본 논문에서는 프로세서의 PCM (Performance Counter Monitor)를 이용한 실시간 FLUSH+RELOAD 공격 탐지 기법을 제안한다. 탐지 방법의 개발을 위해 우선 공격이 발생하는 동안 PCM의 여러 카운터들의 값들의 변화를 4가지 실험을 통해 관찰하였다. 그 결과, 3가지 중요한 요인에 의해 공격 탐지를 할 수 있다는 것을 발견하였다. 이를 바탕으로 머신 러닝의 logistic regression과 ANN(Artificial Neural Network)를 사용해 결과에 대한 각각 학습을 시킨 뒤 실시간으로 공격에 대한 탐지를 할 수 있는 알고리즘을 개발하였다. 이 탐지 알고리즘은 일정한 시간동안 공격을 진행하여 모든 공격을 감지하는데 성공하였고 상대적으로 적은 오탐률을 보여주었다.

FLUSH+RELOAD attack exposes the most serious security threat among cache side channel attacks due to its high resolution and low noise. This attack is exploited by a variety of malicious programs that attempt to leak sensitive information. In order to prevent such information leakage, it is necessary to detect FLUSH+RELOAD attack in real time. In this paper, we propose a novel run-time detection technique for FLUSH+RELOAD attack by utilizing PCM (Performance Counter Monitor) of processors. For this, we conducted four kinds of experiments to observe the variation of each counter value of PCM during the execution of the attack. As a result, we found that it is possible to detect the attack by exploiting three kinds of important factors. Then, we constructed a detection algorithm based on the experimental results. Our algorithm utilizes machine learning techniques including a logistic regression and ANN(Artificial Neural Network) to learn from different execution environments. Evaluation shows that the algorithm successfully detects all kinds of attacks with relatively low false rate.

Ethernet ring protection (ERP) technology, which is defined in ITU-T Recommendation G.8032, has been developed to provide carrier grade recovery for Ethernet ring networks. However, the filtering database (FDB) flush method adopted in the current ERP standard has the drawback of introducing a large amount of transient traffic overshoot caused by flooded Ethernet frames right after protection switching. This traffic overshooting is especially critical when a ring provides services to a large number of clients. According to our experimental results, the traditional FDB flush requires a link capacity about sixteen times greater than the steady state traffic bandwidth. This paper introduces four flush optimization schemes to resolve this issue and investigates how the proposed schemes deal with the transient traffic overshoot on a multi-ring network under failure conditions. With a network simulator, we evaluate the performance of the proposed schemes and compare them to the conventional FDB flush scheme. Among the proposed methods, the extended FDB advertisement method shows the fastest and most stable protection switching performance.