• 대한수학회보
• /
• 제53권1호
• /
• pp.1-20
• /
• 2016

The general number field sieve (GNFS) is asymptotically the fastest known factoring algorithm. One of the most important steps of GNFS is to select a good polynomial pair. A standard way of polynomial selection (being used in factoring RSA challenge numbers) is to select a nonlinear polynomial for algebraic sieving and a linear polynomial for rational sieving. There is another method called a nonlinear method which selects two polynomials of the same degree greater than one. In this paper, we generalize Montgomery's method [12] using geometric progression (GP) (mod N) to construct a pair of nonlinear polynomials. We also introduce GP of length d + k with $1{\leq}k{\leq}d-1$ and show that we can construct polynomials of degree d having common root (mod N), where the number of such polynomials and the size of the coefficients can be precisely determined.

• 한국지형학회지
• /
• 제27권2호
• /
• pp.19-28
• /
• 2020

Grain size analysis is the most basic procedure for identifying the origin, transport and sedimentation processes of sediments, and is widely used in geomorphology and sedimentology. Traditionally, grain size was determined by a sieve-pippette method, but the use of automated analyzers is increasing in recent years. These analyzers have many advantages over traditional techniques, but the measurement results are not always the same. It is still difficult to solve the pretreatment problem such as incomplete diffusion and residual organic matter, and inappropriate results may be obtained. This study compared image-based grain size analysis and sieve analysis to verify its statistical reliability, and conducted experiments to enhance the measurement accuracy using shape parameters. The results showed that the image-based analysis overestimated the grain size of sand dunes by about 7% compared to the sieve analysis, but the two measurements were not statistically different. In addition, by using shape parameters, such as aspect ratio, sphericity, and convexity, improved statistics were obtained compared to the original data. Using the morphological properties of the individual grains is a complementary method to the incomplete pretreatment of the grain size analysis process, and at the same time, it will contribute to improving the accuracy and reliability of the results.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
• /
• pp.205-210
• /
• 2002

As the deposits of natural sands have slowly been depleted, it has resulted in an increase in manufactured fine aggregate (MFA). Standard specifications for fine aggregate for concrete contained in KS F 2558 permit a maximum of 7 percent finer than the No. 200 sieve (75${\mu}{\textrm}{m}$). Since the production process for MFA normally generates 10 to 20 percent of micro fines-which is defined as aggregates passing the No. 200 sieve (75${\mu}{\textrm}{m}$)-more than permitted by specifications, Excess fines must be removed by screening and/or washing operations. The amount of by-products will continue to grow as production increases with environmental discharge restrictions. This fundamental study focuses on experimental research for the adequacy of use of micro fines included in crushed aggregate using methylene blue test. Total of 63 types of sands from seven different rocks were tested. Based on the test results, the methylene blue test was turned out to be a good indicator of the quality of micro fines for concrete and a supplementary article and an amendment of the KS standard were recommended.

• 대한토목학회논문집
• /
• 제7권3호
• /
• pp.213-221
• /
• 1987

국내의 각 공장에서 생산된 플라이애쉬 15종류를 수집하여 콘크리트용 혼화재료로 이용하기 위한 연구의 일환으로 화학성분, 물리적 성질을 조사하고 플라이애쉬 풀의 유동성을 측정하였다. 본 연구에서 국산 플라이애쉬의 화학성분은 한국공업규격의 규정을 만족하였으나 강열감량이 약간 크게 나타났다. 한편 물리적 성질 중 비표면적과 표준체의 잔류량 및 단위중량, 표준체의 잔류량과 강열감량과의 사이에서 상관성을 알아냈다. 그리고 시멘트 풀과 동일한 유동성 을 얻기 위한 플라이애쉬 풀의 물결합재비가 크게 요구됨을 알았다.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 1994년도 가을 학술발표회 논문집
• /
• pp.265-272
• /
• 1994

The relative density seems to be important as a factor of controlling the physical properties in the case of cohesionless soil ground as sand. Therefore, the study is more important about the method for reappearing the same relative density when the specimen of shearing test is to be produced or the model test of ground is to be made. In this study, the apparatus making use of the multiple sieving pluviation method - one of the reappearance of relative density - could be made. Using this apparatus, tests were practiced varying the factors such as the size of sieve mesh and the number of sieve, the amount of falling discharge, the falling height etc. about the standard sand in Jumunjin and Hadong sand. When laboratory test is performed by the cohensionless soil , it presents the method for reappearing of the relative density in field.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제9권1호
• /
• pp.296-308
• /
• 2015

Advanced Encryption Standard (AES) is widely used for protecting wireless sensor network (WSN). At the Workshop on Cryptographic Hardware and Embedded Systems (CHES) 2012, G$\acute{e}$rard et al. proposed an optimized collision attack and break a practical implementation of AES. However, the attack needs at least 256 averaged power traces and has a high computational complexity because of its byte wise operation. In this paper, we propose a novel double sieve collision attack based on bitwise collision detection, and an improved version with an error-tolerant mechanism. Practical attacks are successfully conducted on a software implementation of AES in a low-power chip which can be used in wireless sensor node. Simulation results show that our attack needs 90% less time than the work published by G$\acute{e}$rard et al. to reach a success rate of 0.9.

• 물과 미래
• /
• 제7권2호
• /
• pp.83-91
• /
• 1974

Fill Type Dam에 있어서 일반적으로 축조재료는 경제성을 감안하여 Dam Site 부근에서 구해야하므로 Core 용재료로서는 차수성의 문제만 해결된다면 마시토도 사용가능할 것이라는 전제하에 본문에서는 마사토를 단독 또는 혼합재료로서 각종시험을 실시하여 사용가능성 여부를 검토하고 기사용범위를 정함으로써 앞으로의 사용자들에게 편의를 제공코저 한다.

• 한국산림과학회지
• /
• 제84권2호
• /
• pp.166-177
• /
• 1995

본 연구의 내용은 임도건설(林道建設) 예정지역(豫定地域)의 흙을 어떻게 토질(土質) 역학적(力學的)으로 실험하여 실제적으로 응용할 수 있는가를 다루는 것이다. 이를 위해 8개 플롯에서 각 플롯 당 2 개씩 총 16개의 토양시료(土壤試料)를 채취하였다. 실험내용은 흙이 흩어지기 전후의 단위중량(單位重量), 함수량(含水量), 액성(液性) 및 소성한계(塑性限界), 다짐도 시험(試驗), 입도시험(粒度試驗) 등이다. 흩어지기(교란(攪亂)) 전후의 전체 단위중량(${\rho}_t$)은 각각 $1.69g/cm^3$과 $1.19g/cm^3$이었으며, 함수량(含水量)은 21.0%와 20.5%였다. 체분석과 비중계(比重計)에 의한 입도시험결과 얻은 균등계수(均等係數) U와 곡율계수(曲率係數) C는 각각 125와 0.42를 보이고 있어 전체적으로 좋은 입도분포는 아니었다. USCS에 의한 토양분류는 SM(실트질 모래 내지 모래실트 혼합토)으로서 성토재료(盛土材料)로서는 좋지 않은 것으로 보인다. 다짐시험결과 자연상태의 단위중량(${\rho}$)과 최적(最適) 단위중량(單位重量)(${\rho}pr$)은 각각 $1.40{\pm}0.065g/cm^3$과 $1.88{\pm}0.049g/cm^3$로 나타났는데, 이것은 ${\rho}pr$에 도달하기 위해 성토시(盛土時) 더 많은 다짐작업과 토량(土量)이 필요함을 의미한다.

• 대한치과보철학회지
• /
• 제36권2호
• /
• pp.389-423
• /
• 1998

This investigation was designed to determine the effectiveness of the posterior occlusal schemes on masticatory activity during mastication in complete denture. Twelve edentulous subjects were selected for this study. All subjects had no past history and no functional abnormality on masticatory system and TMjoint. And, they had residual ridge of favorable morphology, firm mucosa and Class I skeletal jaw relationship, Twelve experimental denture with interchangeable occlusions(0-degree teeth, 30-degree teeth, Levin teeth and S-A teeth) were constructed for this study. The masticatory performance was analyzed by means of standard sieve(10, 16, 20, 30sieve), and the electrical activity from selected muscles(Temporalis and Masseter muscle) was recorded simultaneously with electromyography (Bio-Pak system) as the subject masticated test foods (rice, peanut and gum) with four different occlusal schemes. Mandibular movement was, also, measured with Sirognathography(Bio-Pak system). These recordings were performed in immediately, after 1 week and after 2 weeks of insertion of complete denture. The results were as fellows; 1. The average masticatory performance of 0-degree artificial teeth was higher than any other artificial teeth. 2. Masticatory performance in denture wearer was affected preferentially by food and artificial occlusal schemes. 3. During chewing, there was a statistical difference of EMG activity between masseter and temporal muscle(p<0.01). Especially, EMG activity of working masticatory muscle was highly affected by food rather than by artificial occlusal schemes. 4. In denture wearer, the velocity of opening was not affected by food, whereas, the velocity of closing was faster in soft food chewing than in hard food chewing, and the amount of vertical displacement was grater in chewing of soft and large bolus than in chewing of hard and small bolus. However, the amount of lateral displacement showed conversely(p<0.05). 5. It was considered that masticatory performance in denture wearer is not affected by the condition of residual ridge. the history of denture wear, the preference, the adaptation to artificial teeth and the total mesiodistal length of artificial posterior teeth.

• 대한치과보철학회지
• /
• 제34권3호
• /
• pp.539-573
• /
• 1996

This investigation was designed to determine the effectiveness of the posterior occlusal schemes on masticatory activity during mastication in complete denture. Twelve edentulous subjects were selected for this study. All subjects had no past history and no functional abnormality on masticatory system and TMjoint. And, they had residual ridge of favorable morphology, firm mucosa and Class I skeletal jaw relationship, Twelve experimental denture with interchangeable occlusions(0-degree teeth, 30-degree teeth, Levin teeth and S-A teeth) were constructed for this study. The masticatory performance was analyzed by means of standard sieve(10, 16, 20, 30sieve), and the electrical activity from selected muscles(Temporalis and Masseter muscle) was recorded simultaneously with electromyography(Bio-Pak system) as the subject masticated test foods (rice, peanut and gum) with four different occlusal schemes. Mandibular movement was, also, measured with Sirognathography(Bio-Pak system). These recordings were performed in immediately, after 1 week and after 2 weeks of insertion of complete denture. The results were as follows; 1. The average masticatory performance of 0-degree artificial teeth was higher than any other artificial teeth. 2. Masticatory performance in denture wearer was affected preferentially by food and artificial occlusal schemes. 3. During chewing, there was a statistical difference of EMG activity between masseter and temporal muscle(p<0.01). Especially, EMG activity of working masticatory muscle was highly affected by food rather than by artificial occlusal schemes. 4. In denture wearer, the velocity of opening was not affected by food, whereas, the velocity of closing was faster in soft food chewing than in hard food chewing, and the amount of vertical displacement was grater in chewing of soft and large bolus than in chewing of hard and small bolus. However, the amount of lateral displacement showed conversely (p<0.05). 5. It was considered that masticatory performance in denture wearer is not affected by the condition of residual ridge, the history of denture wear, the preference, the adaptation to artificial teeth and the total mesiodistal length of artificial posterior teeth.