• Title, Summary, Keyword: 소수들의 쌍

Search Result 11, Processing Time 0.048 seconds

A study on the approximation function for pairs of primes with difference 10 between consecutive primes (연속하는 두 소수의 차가 10인 소수 쌍에 대한 근사 함수에 대한 연구)

  • Lee, Heon-Soo
    • Journal of The Korea Internet of Things Society
    • /
    • v.6 no.4
    • /
    • pp.49-57
    • /
    • 2020
  • In this paper, I provided an approximation function Li*2,10(x) using logarithm integral for the counting function π*2,10(x) of consecutive deca primes. Several personal computers and Mathematica were used to validate the approximation function Li*2,10(x). I found the real value of π*2,10(x) and approximate value of Li*2,10(x) for various x ≤ 1011. By the result of theses calculations, most of the error rates are margins of error of 0.005%. Also, I proved that the sum C2,10(∞) of reciprocals of all primes with difference 10 between primes is finite. To find C2,10(∞), I computed the sum C2,10(x) of reciprocals of all consecutive deca primes for various x ≤ 1011 and I estimate that C2,10(∞) probably lies in the range C2,10(∞)=0.4176±2.1×10-3.

A Comparison of Hydrodynamic Characteristics of Single and Tandem Strut SWATH Ships (하나 또는 두개의 지주를 갖는 소수선면 쌍동선의 유체동역학적 특성 비교)

  • Ho-Hwan Chun
    • Journal of the Society of Naval Architects of Korea
    • /
    • v.29 no.3
    • /
    • pp.102-116
    • /
    • 1992
  • This report is to provide a comparison of the hydrodynamic characteristics of a single strut SWATH(Small Waterplane Area Twin Hull) model and a tandem(twin) strut SWATH model. The hydrodynamic characteristics included are the resistance in calm water, 6 degree freedom of motion responses in stationary and with forward speeds, and wave loadings etc. All these quantities are measured in the towing tank and compared with the computational results. Based on the present study, the pros and cons for single and tandem strut SWATH designs are clarified and some design suggestions are made.

  • PDF

On the Added Resistance of SWATH Ships in Waves (파랑중에서 SWATH선의 부가저항에 관하여)

  • Ho-Hwan Chun
    • Journal of the Society of Naval Architects of Korea
    • /
    • v.29 no.4
    • /
    • pp.75-86
    • /
    • 1992
  • This paper reports theoretical and experimental investigation into the added resistance of SWATH ships in waves. It was revealed from the experimental investigations on various SWATH models that the resistance of the SWATH models in waves is considerably reduced over part of the speed range as the wave height increases. As a first step to Identify it, the first and second order wave forces have been investigated barred on a linearised 3-D diffraction theory together with simplified boundary conditions and same results are reported herein. Also, the speed performance of SWATH ships in rough seas is compared with those of equivalent monohulls as well as with those of advanced high speed marine vehicles.

  • PDF

A Study on the Learning-Teaching Plan about a Essential Concept of Decimal Fraction Based on Decimal Positional Notation (위치적 십진기수법을 본질로 하여 조직한 소수 개념 지도 방안 연구)

  • Kang, Heung-Kyu
    • Journal of Elementary Mathematics Education in Korea
    • /
    • v.15 no.1
    • /
    • pp.199-219
    • /
    • 2011
  • In this thesis, we designed a experimental learning-teaching plan of 'decimal fraction concept' at the 4-th grade level. We rest our plan on two basic premises. One is the fact that a essential concept of decimal fraction is 'polynomial of which indeterminate is 10', and another is the fact that the origin of decimal fraction is successive measurement activities which improving accuracy through decimal partition of measuring unit. The main features of our experimental learning-teaching plan is as follows. Firstly, students can experience a operation which generate decimal unit system through decimal partitioning of measuring unit. Secondly, the decimal fraction expansion will be initially introduced and the complete representation of decimal fraction according to positional notation will follow. Thirdly, such various interpretations of decimal fraction as 3.751m, 3m+7dm+5cm+1mm, $(3+\frac{7}{10}+\frac{5}{100}+\frac{1}{1000})m$ and $\frac{3751}{1000}m$ will be handled. Fourthly, decimal fraction will not be introduced with 'unit decimal fraction' such as 0.1, 0.01, 0.001, ${\cdots}$ but with 'natural number+decimal fraction' such as 2.345. Fifthly, we arranged a numeration activity ruled by random unit system previous to formal representation ruled by decimal positional notation. A experimental learning-teaching plan which presented in this thesis must be examined through teaching experiment. It is necessary to successive research for this task.

  • PDF

Direct bonding of Si(100)/Si$_3$N$_4$∥Si (100) wafers using fast linear annealing method (선형열처리를 이용한 Si(100)/Si$_3$N$_4$∥Si (100) 기판쌍의 직접접합)

  • Lee, Young-Min;Song, Oh-Song;Lee, Sang-Hyun
    • Korean Journal of Materials Research
    • /
    • v.11 no.5
    • /
    • pp.427-430
    • /
    • 2001
  • We prepared 10cm-diameter Si(100)/500 $\AA$-Si$_3$N$_4$/Si(100) wafer Pairs adopting 500 $\AA$ -thick Si$_3$N$_4$layer as insulating layer between single crystal Si wafers. Si3N, is superior to conventional SiO$_2$ in insulating. We premated a p-type(100) Si wafer and 500 $\AA$ -thick LPCVD Si$_3$N$_4$∥Si (100) wafer in a class 100 clean room. The cremated wafers are separated in two groups. One group is treated to have hydrophobic surface and the other to have hydrophilic. We employed a FLA(fast linear annealing) bonder to enhance the bond strength of cremated wafers at the scan velocity of 0.1mm/sec with varying the heat input at the range of 400~1125W. We measured bonded area using a infrared camera and bonding strength by the razor blade crack opening method. We used high resolution transmission electron microscopy(HRTEM) to probe cross sectional view of bonded wafers. The bonded area of two groups was about 75%. The bonding strength of samples which have hydrophobic surface increased with heat input up to 1577mJ/$m^2$ However, bonding strength of samples which have hydrophilic surface was above 2000mJ/$m^2$regardless of heat input. The HRTEM results showed that the hydrophilic samples have about 25 $\AA$ -thick SiO layer between Si and Si$_3$N$_4$/Si and that maybe lead to increase of bonding strength.

  • PDF

Ultrastructural Studies of Germ Cell Developments and Atypical Cells Occurred During Spermatogenesis in the Acini, and the Cyclic Changes in the Epithelial Cells With the Developmental Phases of the Seminal Vesicle in Rapana venosa (Valencienes) (피뿔고둥 Rapana venosa (Valencienes) 정소소엽 내에서의 생식세포 발달과 정자형성과정 중 출현하는 비정형 세포들의 미세구조적 연구 및 저정낭의 발달단계에 따른 상피세포들의 주기적 변화)

  • Lee, Il Ho;Chung, Jae Seung
    • The Korean Journal of Malacology
    • /
    • v.31 no.1
    • /
    • pp.9-19
    • /
    • 2015
  • Germ cell development and cyclic changes in the epithelial cells of the seminal vesicle of the male rapa whelk, Rapana venosa, were investigated by cytological and histological observations. The process of germ cell development can be classified into five stages: (1) spermatogonial, (2) primary spermatocyte, (3) secodary spermatocyte, (4) spermatid, and (5) spermatozoon. In particular, four atypical cells (Type IA, IB, IIA and IIB cells) occur among normal germ cells in the acini during spermatogenesis. Presumably, the atypical cells, which have lysosome-like vacuoles or lysosome-like bodies in the cells, are involved in breakdown and absorption themselves in the acini. However, atypical cells were not found in the epithelial cells of the inner layer of the seminal vesicle. A considerable amount of spermatozoa are transported from the testis towards the the seminal vesicles until late July. The main coupulation period is between June and July. The process of the cyclical changes of the seminal vesicles can be classified into three phases: (1) resting, (2) accumulating, and (3) spent. Yellow granular bodies are involved in resorption or digestion of residual spermatozoa.

Assessing the Utilization and Interrelatedness of Scopus Subject Categories (Scopus에 설정된 주제분류 활용도 및 상호 연관성에 대한 고찰)

  • Kim, Eungi
    • Journal of Korean Library and Information Science Society
    • /
    • v.50 no.1
    • /
    • pp.251-272
    • /
    • 2019
  • This study investigated the utilization and interrelatedness of Scopus subject categories. To conduct this study, major and minor subject categories of journals listed in the 2017 Scopus index were used. The results showed varying degrees of interrelatedness of subject categories. At the major subject category level, the utilization was the highest in Medicine, while Social Sciences showed a greater degree of interrelatedness in comparison to Medicine. Yet, at the minor subject level, 2700 General Medicine was particularly dominant in terms of utilization and interrelatedness. Moreover, co-occurrences of minor subject categories showed varying degrees of interrelatedness between pairs of minor subject categories. Pairs of minor subject categories showed the following characteristics: a) two subject categories having identical or closely identical descriptions, b) two different categories having an interrelationship by subject areas, and c) one category conceptually encompassing another category. Due to varying degrees of utilization and interrelatedness among subject categories, minor subject categories that may greatly influence the major subject categories in conducting research studies should be investigated in detail.

Fine Structural Analysis of the Attachment Devices in the Jumping Spider Plexippus setipes (깡충거미 표면 접착장치의 미세구조 분석)

  • Moon, Myung-Jin;Park, Jong-Gu
    • Applied Microscopy
    • /
    • v.39 no.2
    • /
    • pp.149-156
    • /
    • 2009
  • Fine structure of the dry adhesion system in the tarsal appendages of the jumping spider Plexippus setipes (Araneae: Salticidae) with examined using field emission scanning electron microscope (FESEM). The jumping spiders have the distinctive attachment apparatus for adhesion on smooth dry surface without sticky fluids. They attach to rough substrates using tarsal claws, however attachment on smooth surfaces is achieved by means of a tuft-like hair called a scopula. All eight legs have the scopulae with a pair of claws on the tip of feet, and each scopula is composed of two groups of setae that are capable of dry adhesion on smooth surface. The apex of each seta is flattened pad bearing many specialized adhesive setules on one side. The cuticular sensillae are interspersed at the dorsal surface of the seta. It has been revealed by this research that the contact area of the setule is always a triangular shape, and these cuticular surfaces are connected by the elongated stalks from the underlying setae. Moreover, adhesion between the numerous setules and the setae was prevented by the microscopic hairs, since these were interspersed on the upper side of the setae.

Behavioural Analysis of Password Authentication and Countermeasure to Phishing Attacks - from User Experience and HCI Perspectives (사용자의 패스워드 인증 행위 분석 및 피싱 공격시 대응방안 - 사용자 경험 및 HCI의 관점에서)

  • Ryu, Hong Ryeol;Hong, Moses;Kwon, Taekyoung
    • Journal of Internet Computing and Services
    • /
    • v.15 no.3
    • /
    • pp.79-90
    • /
    • 2014
  • User authentication based on ID and PW has been widely used. As the Internet has become a growing part of people' lives, input times of ID/PW have been increased for a variety of services. People have already learned enough to perform the authentication procedure and have entered ID/PW while ones are unconscious. This is referred to as the adaptive unconscious, a set of mental processes incoming information and producing judgements and behaviors without our conscious awareness and within a second. Most people have joined up for various websites with a small number of IDs/PWs, because they relied on their memory for managing IDs/PWs. Human memory decays with the passing of time and knowledges in human memory tend to interfere with each other. For that reason, there is the potential for people to enter an invalid ID/PW. Therefore, these characteristics above mentioned regarding of user authentication with ID/PW can lead to human vulnerabilities: people use a few PWs for various websites, manage IDs/PWs depending on their memory, and enter ID/PW unconsciously. Based on the vulnerability of human factors, a variety of information leakage attacks such as phishing and pharming attacks have been increasing exponentially. In the past, information leakage attacks exploited vulnerabilities of hardware, operating system, software and so on. However, most of current attacks tend to exploit the vulnerabilities of the human factors. These attacks based on the vulnerability of the human factor are called social-engineering attacks. Recently, malicious social-engineering technique such as phishing and pharming attacks is one of the biggest security problems. Phishing is an attack of attempting to obtain valuable information such as ID/PW and pharming is an attack intended to steal personal data by redirecting a website's traffic to a fraudulent copy of a legitimate website. Screens of fraudulent copies used for both phishing and pharming attacks are almost identical to those of legitimate websites, and even the pharming can include the deceptive URL address. Therefore, without the supports of prevention and detection techniques such as vaccines and reputation system, it is difficult for users to determine intuitively whether the site is the phishing and pharming sites or legitimate site. The previous researches in terms of phishing and pharming attacks have mainly studied on technical solutions. In this paper, we focus on human behaviour when users are confronted by phishing and pharming attacks without knowing them. We conducted an attack experiment in order to find out how many IDs/PWs are leaked from pharming and phishing attack. We firstly configured the experimental settings in the same condition of phishing and pharming attacks and build a phishing site for the experiment. We then recruited 64 voluntary participants and asked them to log in our experimental site. For each participant, we conducted a questionnaire survey with regard to the experiment. Through the attack experiment and survey, we observed whether their password are leaked out when logging in the experimental phishing site, and how many different passwords are leaked among the total number of passwords of each participant. Consequently, we found out that most participants unconsciously logged in the site and the ID/PW management dependent on human memory caused the leakage of multiple passwords. The user should actively utilize repudiation systems and the service provider with online site should support prevention techniques that the user can intuitively determined whether the site is phishing.

Genetic Polymorphism of Epoxide Hydrolase and GSTM1 in Chronic Obstructive Pulmonary Disease (만성폐쇄성폐질환 발생에 Epoxide hydrolase와 GSTM1유전자 다형성의 의의)

  • Park, Sang Sun;Kim, Eun Joung;Son, Chang Young;Wi, Jeong Ook;Park, Kyung Hwa;Cho, Gye Jung;Ju, Jin Young;Kim, Kyu Sik;Kim, Yu II;Lim, Sung Chul;Kim, Young Chul;Park, Kyung Ok;Na, Kook Joo
    • Tuberculosis and Respiratory Diseases
    • /
    • v.55 no.1
    • /
    • pp.88-97
    • /
    • 2003
  • Background : Although smoking is a major cause of chronic obstructive pulmonary disease (COPD), only 10-20% of cigarette smokers develop symptomatic COPD, which suggests the presence of genetic susceptibility. This genetic susceptibility to COPD might depend on variations in the activities of the enzyme that detoxify hazardous chemical products, such as microsomal epoxide hydrolase (mEPHX) and glutathione-S transferase M1 subunit (GSTM1) genes. Methods : The genotypes of 58 patients with COPD, and 79 age matched control subjects, were determined by a polymerase chain reaction, followed by restriction fragment length polymorphism (PCR-RFLP) for the mEPHX, and multiplex PCR for the GSTM1. Results : GSTM1 was deleted in 53.3% of the subjects. There was no difference in GSTM1 deletion rates between the COPD patients (32/58, 55.2%) and the control subjects (41/79, 51.9%). The combination patterns of two polymorphisms of mEPHX showed slow enzyme activity in 29(21.2%), normal in 73(53.3%) and fast in 32(23.4%). The COPD group (7/57, 12.3%) showed a significantly lower incidence of slow enzyme activity compared to the control subjects (22/77, 28.6%, p<0.05). However, when the COPD and control groups were compared with smokers only, there were no significant differences in the genotypes of GSTM1 and mEPHX. Conclusion : The genotypes of GSTM1 and mEPHX were not significant risk factors of COPD in this cohort of study.