TCP 플러딩 공격 방어를 위한 네트워크 인터페이스용 고성능 TCP 프락시 제어 로직 구현

김병구(Byoungkoo Kim),김익균(Ikkyun Kim),김대원(Daewon Kim),오진태(Jin-tae Oh),장종수(Jong-soo Jang),정태명(Tai-Myoung Chung) 한국정보보호학회 2011 정보보호학회논문지 Vol.21 No.2

본 논문은 인터넷 서버의 정상적인 TCP 연결을 방해하는 형태의 DDoS(Distributed Denial of Service) 공격으로부터 서버를 보호하고 원활한 서비스를 제공하기 위한 DDoS 공격 차단 방법에 관한 것이다. 즉, 유효한 TCP 연결만을 전달해주는 기능을 가진 네트워크 인터페이스 카드에서의 고속 TCP 연동 로직(NIC_Cookie)에 대하여 기술한다. NIC_Cookie의 장점은 플러딩 공격 상태에서도 실시간으로 공격 패킷을 차단하고 정상적인 패킷만이 메인 CPU로 전달될 수 있도록 하기 때문에, 서버의 CPU 성능과 외부 네트워크의 구성 등에 영향을 받지 않는다는 것이다. 또한, 패킷 단위로 공격 TCP 세션에 대하여 실시간 차단 대응을 하기 때문에 정상적인 연결 시도에 대하여 잘못된 대응을 할 가능성이 없다. 이와 더불어, NCI_Cookie 로직 추가로 발생하는 지연시간은 패킷 길이와 상관없이 7x10??초 이하의 성능을 보장하며, 본 논문에서는 구현된 NIC_Cookie가 일반적인 플러딩 공격을 실시간으로 방어하면서 그 성능을 보장함을 확인하였다. TCP-related Flooding attacks still dominate Distributed Denial of Service Attack. It is a great challenge to accurately detect the TCP flood attack in hish speed network. In this paper, we propose the NIC_Cookie logic implementation, which is a kind of security offload engine against TCP-related DDoS attacks, on network interface card. NIC_Cookie has robustness against DDoS attack itself and it is independent on server OS and external network configuration. It supports not IP-based response method but packet-level response, therefore it can handle attacks of NAT-based user group. We evaluate that the latency time of NIC_Cookie logics is 7x10?? seconds and we show 2Gbps wire-speed performance through a benchmark test.

분산 서비스 거부 공격 대응을 위한 Secure-NIC 시스템 설계 및 구현

김병구 ( Byoungkoo Kim ),김대원 ( Daewon Kim ),오진태 ( Jin-tae Oh ),장종수 ( Jong-soo Jang ),김익균 ( Ikkyun Kim ) 한국정보처리학회 2011 한국정보처리학회 학술대회논문집 Vol.18 No.2

인터넷의 발전과 더불어 네트워크 상에서의 침입 시도가 갈수록 증가되고 다변화되고 있으며, 특히, 네트워크나 서버의 가용성을 위협하는 형태의 서비스 거부(DoS: Denial of Servie) 공격이 최근 급증하고 있다. 따라서, 본 논문에서는 인터넷 서버의 정상적인 서비스 제공을 방해하는 형태의 분산 서비스 거부(DDoS: Distributed Denial of Service) 공격으로부터 서버를 보호하고 원활한 서비스를 제공하기 위한 Secure-NIC 시스템의 설계 및 구현에 대해서 설명한다. 이는 “CISGDP: CPU-Independent Service Guaranteed DDoS Protection” 이라는 설계 개념하에서, 각종 인터넷 서버에 장착되어 DDoS 공격 등의 네트워크 공격에 대하여 서버의 고유 서비스가 지속적으로 보장될 수 있도록 자체 보안 기능을 NIC(Network Interface Card) 형태로 제공한다.

Deformation Behavior of Ferrite-Austenite Duplex High Nitrogen Steel

Byoungkoo Kim,T. T. T. Trang,김낙준 대한금속·재료학회 2014 METALS AND MATERIALS International Vol.20 No.1

The tensile deformation behavior of ferrite-austenite duplex high nitrogen steel has been investigated byinterrupted tensile tests and compared with that of fully austenitic high nitrogen steel. It shows that ferriteis softer than austenite and most of the strain in early and later stages of deformation is accommodated byferrite, while austenite undergoes a deformation-induced martensitic transformation. Such accommodationof a large amount of strain in ferrite is responsible for rapidly increasing work hardening rate and theresultant higher ultimate tensile strength of duplex high nitrogen steel as compared to those of fully auste-nitic high nitrogen steel, although duplex steel contains a smaller amount of N than austenitic steel.

키 은닉 기법을 활용한 안전하고 신뢰성 있는 사물인터넷 디바이스 인증 기술

김병구(Byoungkoo Kim),윤승용(Seungyong Yoon),강유성(Yousung Kang),최두호(Dooho Choi) 한국정보보호학회 2020 情報保護學會誌 Vol.30 No.1

사물인터넷 환경으로 연결되는 디바이스 종류가 점점 다양해지고, 이를 통해 유통되고 처리되는 정보의 양이 절대적으로 증가함에 따라 여러 보안 이슈들도 함께 부각 되고 있다. 무엇보다도, 사물인터넷 기술은 우리 실생활에 직접 접목되기 때문에, 기존 사이버공간의 위험이 현실 세계로 전이 및 확대될 수 있다는 우려가 점차 증대되고 있다. 특히, 사물인터넷 기기들의 인증 및 데이터 보호에 필요한 키의 누출은 불법 복제 및 데이터 유출을 통한 경제적, 산업적 손실을 유발하고 있는 실정이다. 따라서, 본 논문에서는 이러한 보안 위협에 대응하기 위한 하드웨어 기반의 키 은닉 기술 및 소프트웨어 기반의 키 은닉 기술의 연구 동향에 대해서 살펴보고, 이를 활용한 사물인터넷 디바이스 인증기법을 제시한다. 이는 하드웨어 및 소프트웨어 기반의 키 은닉 기술을 적절히 접목함으로써, 여러 보안 취약점으로 인한 인증키 노출 위협을 근본적으로 차단하여 효과적이고 안전한 인증키 관리를 가능하게 한다. 즉, 본 논문은 다양한 키 은닉 기술에 대해서 설명하고, 이를 토대로 보다 안전하고 신뢰성 있는 사물인터넷 디바이스 인증 기술을 제공하고자 한다.

Soil Ecological Effects of Chainsaw Lubricant Contamination by Oil Type in a Forest Nursery Field

Ikhyun Kim,Jeongjae Kim,Eugene Ha,Byoungkoo Choi 강원대학교 산림과학연구소 2022 강원대학교 산림과학연구소 학술대회 Vol.2022 No.10

Tree cutting is commonly performed using chainsaws in South Korea. While the chain is rotating, the oil pump releases lubricant from the reservoir on the guide bar as the throttle is pressed. Sawdust, stained with released lubricant, is sprayed on the surface soil during tree cutting. And some released lubricant droplets are scattered on the ground directly. This study was conducted to assess the effect of lubricant on forest soil properties in a nursery field. We examined the persistence of 16PAHs and TPH in lubricant scattered soil and monitored the changes in soil biological properties (soil respiration, soil bacterial community richness and diversity) from November 15th, 2021 to September 19th, 2022. The research site included a total of 4 plots consisting of one control plot (CP) and three treatment plots (T-plot), and each plot consists of three subplots (3✕3 m; a total of 12 subplots). Three different types of lubricants of 100 ml/m2 were scattered on the soil surface of each T-plot (Bio-oil scattered plot, BP; Premium mineral oil scattered plot, PMP; Mineral oil scattered plot, MP) on November 16th, 2021. After approximately six months of lubricant scattering treatment, the concentration of soil increased in BP by 346.9%, PMP by 138.1%, MP by 691.9%, and soil TPH concentration decreased in BP by 48.2%, PMP by 24.0%, and increased in MP by 124.5%. The average soil respiration within the study period was lower at PMP (0.46 g CO2/m2/hr) than at CP (0.54 g CO2/m2/hr), BP (0.57 g CO2/m2/hr), and MP (0.59 g CO2/m2/hr), but there was no significant difference (p<0.05). In addition, lubricant type had no significant effect on soil bacterial community richness and diversity during the study period (p<0.05).

Detection of Surface Displacement in Timber Harvested Area and Mapping Erosion Risk by Classification Algorithm

Jeongjae Kim,Ikhyun Kim,Eugene Ha,Byoungkoo Choi 강원대학교 산림과학연구소 2022 강원대학교 산림과학연구소 학술대회 Vol.2022 No.10

Soil surface displacement occurs often following timber harvesting. This displacement is caused by canopy removal from the forest area which makes bare soil to be exposed directly to the rainfall. Thus, the displacement may differ in due to precipitation intensity, and this phenomenon results in the displacement prediction to be uncertain. In this study, we investigated on 1) calculating displacement on timber harvested area in research forest by photogrammetry method, and 2) assessing erosion risk of the area by using three different supervised machine learning classification models. Two time-series of point cloud data (PCD) were acquired by photogrammetry method from June 10, 2022 and July 9, 2022, respectively. These two PCD sets were registered by ground control point (GCP). For displacement estimation, DEM of difference (DoD) was calculated by subtracting DEMs from registered PCD sets. A total of nine terrain variables were generated for analyzing the spatial relationship between displacements and topographic features. Erosion risk was analyzed by three different classification algorithms: random forest (RF), extra gradient boost (XGB), logistic regression (LG). Best performed model was RF with overall accuracy (OA) of 72.9% followed by XGB model (72%), and LG model (71.7%). The results of this research indicate that machine learning based classification algorithms have better performances on erosion risk analysis than statistical algorithm through this research.

A study on wettability according to the application of ultrathin palladium plating

Byeong Chan Choi,Byung-Jun Kim,Byoungkoo Kim,Hyoung Chan Kim 한국표면공학회 2023 한국표면공학회 학술발표회 초록집 Vol.2023 No.11-1

Effects of Annealing Treatment on the Anisotropy Behavior of Cold-Rolled High-Manganese Austenite Stainless Steels

Minha Park,Moon Seok Kang,Geon‑Woo Park,Hyoung Chan Kim,Hyoung‑Seok Moon,Byoungkoo Kim,Jong Bae Jeon,Hyunmyung Kim,Hee‑Sang Park,Se‑Hun Kwon,Byung Jun Kim 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.10

High-Mn (over 24 wt%) austenitic steels recently have been developed with excellent mechanical properties such as highstrength and ductility at very low temperatures for cryogenic application. Especially, cold-rolling process is and effectivemethod to increased yield and tensile strength of high-Mn steel when making products. In our previous work, we haveinvestigated the correlation between microstructure and mechanical properties due to recrystallization without consideringthe characteristics of the cold-rolling direction of high-Mn steels.In this study, we evaluated the effects of anisotropicbehaviors on the heat treatment of cold-rolling high-Mn steels. Despite the heat treatment, differences between transverseand longitudinal direction in the cold-rolled conditions generally affected the recrystallized microstructure. Such anisotropicbehaviors caused changes in mechanical properties such as tensile and Charpy impact test, as microstructure along coldrollingdirection.

Effects of Experimental Drought on Soil Bacterial Community in a Larix Kaempferi Stand

Kim, Beomjeong,Choi, Byoungkoo Institute of Forest Science 2018 Journal of Forest Science Vol.34 No.3

Drought alters soil microorganisms; however, it is still not clear how soil microbes respond to severe drought conditions. In this study, the responses of soil bacterial community to experimental drought in a coniferous stand were examined. Six $6m{\times}6m$ plots with three replicates of control and drought treatments were delimited. PCR amplification and Illumina sequencing were conducted for cluster analysis of soil bacterial community and species richness and species diversity was analyzed. Along the 393 days of simulated drought from July 2016 to October 2017, soil bacterial species diversity slightly increased whereas species richness decreased in both control and roof plots. Moreover, soil bacterial species richness more decreased in roof plots than in controls. Combining these results, soil bacterial activity might have been altered by simulated drought.

Effects of Experimental Drought on Soil CO₂ Efflux in a Larix Kaempferi Stand

Kim, Beomjeong,Yun, Youngjo,Choi, Byoungkoo Institute of Forest Science 2018 Journal of Forest Science Vol.34 No.3

Climate models forecast more frequent and a longer period of drought events which may impact forest soil carbon dynamics, thereby altering the soil respiration (SR) rate. We examine the simulated drought effects on soil $CO_2$ effluxes from soil surface partitioning heterotrophic and autotrophic soil respiration sources. Three replicates of drought plots ($6{\times}6m$) were constructed with the same size of three control plots. We examined the relation between $CO_2$ and soil temperature and soil moisture, each being measured at a soil depth of 15 cm. We also compared which factor affected $CO_2$ efflux more under drought conditions. Total SR, autotrophic respiration (AR) and heterotrophic respiration (HR) were positively correlated with soil temperature (p < 0.05), and the relationships were stronger in roof plots than in control plots. Total SR, AR, and HR were negatively correlated only in roof plots, and the only HR showed a significant correlation (p < 0.05, r = -0.59). Soil respiration rates were more influenced by soil temperature than by soil moisture, and this relationship was more evident under drought conditions.