NIST PQC 공모전 동향 분석 및 표준화 대상 & Round 4 알고리즘 소개

김동천(Dong Cheon Kim),김영범(Young Beom Kim),서석충(Seong Chung Seo) 한국정보보호학회 2023 情報保護學會誌 Vol.33 No.2

뇌에서 발생한 원발성 섬유조직구종 -증례보고-

김동천 ( Dong Cheon Kim ),조준 ( Joon Cho ),조요한 ( Yo Han Cho ),노홍기 ( Hong Gee Roh ),임소덕 ( So Dug Lim ),고영초 ( Young Cho Koh ) 대한뇌종양학회·대한신경종양학회·대한소아뇌종양학회 2009 대한뇌종양학회지 Vol.8 No.2

Malignant fibrous histiocytoma(MFH) is a soft tissue sarcoma arising from the extremities and retroperitoneum in older adults. Primary intracranial MFH is extremely rare. A 29-year-old woman presented with headache showing three large masses on brain magnetic resonance image(MRI). She had undergone extended total gastrectomy with splenectomy under the diagnosis of advanced gastric cancer three years previously. Systemic positron extension tomography(PET) computed tomography(CT) scan on routine follow-up study before the first brain surgery revealed no hot spots. Three masses were totally removed at a single session. The pathology was confirmed to be typical MFH. Two months after the first brain surgery, she underwent tonsillectomy due to a rapidly growing tonsillar mass and the pathology was found out to be MFH. Postoperative neck CT with angiography for the evaluation of hypotension showed no significant finding. Except for the tonsillar mass, she had been symptom free during 10 months after the first brain surgery. Between 11th and 18th months postoperatively, multiple intracranial recurrences including metastatic lesions of the mediastinum and the spine were noticed. She died of pneumonia 20 months after the first brain surgery during salvage chemotherapy. We report a rare case of primary MFH of the brain with a past medical history of advanced gastric cancer.

PQC-DSA 기반 블록체인 기술 동향 조사

김동천(Kim Dong Cheon),서석충(Seo Seog Chung) 한국통신학회 2022 한국통신학회 학술대회논문집 Vol.2022 No.2

본 논문은 기존 블록체인 시스템의 안전성을 공개 키 암호 알고리즘을 이용하여 설명하고, 이후 급속도로 연구되고 있는 양자 컴퓨터에 대한 소개를 통해 현재 이산대수/타원곡선 기반의 공개키 스킴을 탑재한 블록체인 시스템에 대한 취약점이 존재할 수 있음을 분석한다. 또한, 이런 위험성을 예방하기 위해 현재 양자 내성 암호(Post-Quantum Cryptography)가 연구되고 있고, 해당 암호 기술을 블록체인 시스템에 적용할 때 발생할 수 있는 문제점과 이에 관한 연구 동향을 조사하였다.

Ad-hoc 네트워크에서 악의적 노드 관리기법에 관한 연구

김일도,김동천,Kim, Il-Do,Kim, Dong-Cheon 한국정보통신학회 2010 한국정보통신학회논문지 Vol.14 No.12

Ad-hoc 네트워크가 정상적으로 동작하기 위해서는 각 노드가 동등한 권한을 갖고 상호 협조할 때 원활한 통신이 가능하다. 신뢰성을 확보하기 위해 인증된 노드로만 네트워크가 구성이 가능하지만 인증만으로 악의적 행위를 하는 노드를 완전히 배제할 수 없으므로 이들의 행위가 네트워크 전체를 위험에 빠뜨릴 수 있다. 이를 탐지 및 배제해야만 더욱 안전하고 신뢰할 수 있는 네트워크를 유지할 수 있으나 이에 대한 연구는 상대적으로 미흡한 수준이다. 따라서 신뢰 관계에 있는 노드로 구성된 네트워크에서 이기적이거나 악의적인 노드를 탐지하고 배제시켜 결과적으로 네트워크의 안전성과 신뢰성을 유지하고 처리율을 향상시킬 수 있는 방법을 제안한다. An Ad-hoc network will operate properly and provide smooth communication when nodes cooperate mutually with each of them having equal authority. Although it is possible to form a network consisting only of authenticated nodes in order to ensure reliability, authentication by itself is not sufficient to remove malicious nodes and their activities jeopardizing the whole network. Detection and prevention of such activities are vital for maintaining a safe and reliable network, but research on this matter is relatively lacking. Hence a suggestion is made on how to detect and prevent malicious or uncooperative ones among the nodes forming a network by a relationship of mutual trust, thereby maintaining safety and stability of the network and improving its processing abilities

무선센서네트워크에서 다항식 비밀분산을 이용한 공개키 인증방식에 관한 연구

김일도,김동천,Kim, Il-Do,Kim, Dong-Cheon 한국정보통신학회 2009 한국정보통신학회논문지 Vol.13 No.11

센서네트워크의 인증과 관련된 초기의 연구에서는 센서노드의 자원제약적인 특징을 고려하여 대칭키 기반의 인증 방식이 주로 제안되었으나, 최근에는 암호알고리즘의 성능이 개선되고 센서노드의 제조기술이 발달하여 Merkle 트리 방식 등 공개키 기반의 인증 방식도 제안되고 있다. 따라서 본 연구에서는 센서네트워크에 효과적으로 적용될 수 있는 새로운 개념의 다항식 비밀분산을 이용한 공개키 인증방식을 제안하며, hash 함수를 이용한 악의적 노드탐지 기법도 제안한다. 제안된 인증방식은 Shamir의 임계치 기법에 변형된 분산정보의 일종인 지수(exponential) 분산정보 개념을 적용하여 동시에 주변 노드들을 인증하면서 센서노드의 자원을 최소로 사용하고 네트워크의 확장성을 제공한다. Earlier researches on Sensor Networks preferred symmetric key-based authentication schemes in consideration of limitations in network resources. However, recent advancements in cryptographic algorithms and sensor-node manufacturing techniques have opened suggestion to public key-based solutions such as Merkle tree-based schemes. This paper proposes a new concept of public key-based authentication using Polynomial Secret Sharing that can be effectively applied to sensor networks and a detection of malicious node using the hash function. This scheme is based on exponential distributed data concept, a derivative from Shamir's (t,n) threshold scheme, in which the authentication of neighbouring nodes are done simultaneously while minimising resources of sensor nodes and providing network scalability.

유압호스의 가속수명시험에서 굽힘 하중의 영향

백동천(Dong-Cheon Baek),이순복(Soon-Bok Lee),강보식(Bo-Sik Kang),김형의(Hyoung-Eui Kim) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5

The model for accelerated life testing of hydraulic hose was proposed based on failure mechanisms. Flexing effects on the impulse testing of hydraulic hose were estimated as the equivalent pressure with respect to proposed model.

강유전막의 잔류 분극 상태와 내부 전계가 Pt/Pb(Zr,Ti)O₃/Pt 커패시터의 수소 열화 특성에 미치는 영향

김동천,이강운,이원종,Kim, Dong-Cheon,Lee, Gang-Un,Lee, Won-Jong 한국재료학회 2002 한국재료학회지 Vol.12 No.1

The ferroelectric properties of Pb(Zr,Ti)O$_3$[PZT] films degrade when the films with Pt top electrodes are annealed in hydrogen containing environment. This is due to the reduction activity of atomic hydrogen that is generated by the catalytic activity of the Pt top electrode. At the initial stage of hydrogen annealing, oxygen vacancies are formed by the reduction activity of hydrogen mainly at the vicinity of top Pt/PZT interface, resulting in a shift of P-E (polarization-electric field) hysteresis curve toward the negative electric field direction. As the hydrogen annealing time increases, oxygen vacancies are formed inside the PZT film by the inward diffusion of hydrogen ions, as a result, the polarization degrades significantly and the degree of P-E curve shift decreases gradually. The direction and the magnitude of the remnant polarization in the PZT film affect the motion of hydrogen ions which determines the degradation of polarization characteristics and the shift in the P-E hysteresis curve of the PZT capacitor during hydrogen annealing. When the remnant polarization is formed in the PZT film by applying a pre-poling voltage prior to hydrogen annealing, the direction of the P-E curve shift induced by hydrogen annealing is opposite to the polarity of the pre-poling voltage. The hydrogen-induced degradation behavior of the PZT capacitor is also affected by the internal field that has been generated in the PZT film by the charges located at the top interface prior to hydrogen annealing.

산소발생 폐쇄식 SCBA의 서비스 수명 예측 프로그램 -예비연구-

한돈희 ( Don Hee Han ),김동천 ( Dong Cheon Kim ),강민선 ( Min Sun Kang ) 한국산업위생학회 2007 한국산업보건학회지 Vol.17 No.2

A oxygen generating closed-circuit SCBA for escape from fire will be newly developed and then a program for estimating service time for it should be required. A SCBA made on an experimental basis consisted of five components such as half facepiece (mask), KO2 box, oxygen reservoir, CO2 remover and hood. The half mask had a good fitting performance since fit factors for 10 subjects were all above 100. It was found that height of subjects should be the best variable to estimate service time. Measured service time was inversely correlated with height of subjects. Service life time could be estimated by interpolation and extrapolation using inverse relationship between height and measured service time, for example, 28 minutes for male and female of 170 cm during resting, 10 minutes at the walk of 4 km/h and 5 minutes at the walk of 6 km/h considering safety margin of 20%. The study implies that program for estimating service time for the SCBA should require subject`s height, speed of walk (4 km/h and 6 km/h) and fit testing. Considering safety margin, selecting younger subjects would be better. The study on the number of subjects and selecting facial dimensions should be more needed for the final program.

淸州地域 河川 河床堆積物의 重金屬 含量

김동천,이해복 청주대학교 산업과학연구소 1993 産業科學硏究 Vol.11 No.-

The content of such heavy metals as Arsenic (As), Cadmium (Cd), Copper (Cu), Total-Cromium (T-Cr), Manganese (Mn), Mercury (Hg), Lead (Pb) and Zinc (Zn) in the sediments of a total of 25 sites from Mu-Sim, Seok-Nam and Mi-Ho Streams in Chongju area was analyzed during March 1991 ~ February 1992. As the results, the average contents of them in the sediments of Mu-Sim, Seok-Nam and Mi-Ho Streams measured in ㎎/㎏ were 0.89, 2.18, 0.69 in As, 0.64, 0.85, 0.45 in Cd, 1257, 43.54, 5.90 in Cu, 22.55, 218.89, 27.87 in T-Cr, 121.38, 107.59, 67.59 in Mn, 0.054, 0.050, 0.024 in Hg, 8.99, 74.07, 8.92 in Pb and 78.01, 181.78, 57.93 in Zn, respectively. In Seok-Nam Stream, T-Cr and Pb contents were severely high, and Cd, Cu, and Zn contents were relatively high. And especially As content there was higher than that of the other streams. The seasonal change of average contents of heavy metals in the sediments of the streams were not significant. The heavy metal pollution in the sediments of Mu-Sim and Mi-Ho Streams were not severe, but Seok-Nam Stream was severely polluted by much amounts of As, Cd, Cu and Pb which are classified as the special water-contaminating substances, and by T-Cr and Zn which are classified as the common water-contaminating substances. Therefore we suggest that the sediments of Seok-Nam Stream must be removed, because the Mi-Ho Stream and it's lower stream Keum River can continuously be polluted by their upper tributary, Seok-Nam Stream.