Earticle

이더리움은 모든 사용자가 블록체인에 저장된 데이터를 확인할 수 있는 공개형 블록체인이기 때문에 이더리움 상에 서 개인 정보 등의 민감한 데이터를 활용하는 것은 근본적으로 어렵다. 이를 해결하기 위해서 데이터의 기밀성을 보 장하는 프로토콜을 이더리움의 스마트 컨트랙트로 구현하는 것을 고려할 수 있고, 대표적인 기밀성 보장 프로토콜로 zkSNARKs와 함수암호가 있다. 대부분의 기밀성 보장 프로토콜들은 페어링을 주요한 암호 연산으로 사용하기 때 문에 이더리움 상에서 기밀성 보장 프로토콜을 구현하기 위해서는 반드시 페어링이 먼저 구현되어야 한다. 본 논문 에서는 페어링 기반의 기밀성 보장 프로토콜들을 스마트 컨트랙트로 구현하기 위해 페어링 함수를 Solidity 언어로 구현하였고, 페어링 함수의 구현 적합성을 평가함으로써 페어링 함수가 정상적으로 동작함을 확인하였으며, 기존의 이더리움 상에서 페어링을 수행하는 방법과 본 논문의 페어링 함수를 비교하였다. 또한, 페어링 함수를 이용해 페어 링 기반의 암호 프로토콜인 BLS 서명을 스마트 컨트랙트로 구현하고 이더리움 상에서 실행함으로써 본 논문에서 구현한 페어링 함수가 실제 응용에 적용될 수 있음을 확인하였다.

Ethereum is a public blockchain that allows all users to verify data stored in the blockchain, so it is essentially difficult to utilize sensitive data on Ethereum. To resolve this issue, we can consider implementing protocols that ensure confidentiality of data on Ethereum smart contracts. The representative protocols that achieve this goal include zkSNARKs and functional encryption. Since most of these protocols use pairing as a major cryptographic operation, pairing must be implemented to provide Ethereum with confidentiality. In this paper, we implemented pairing functions in the Solidity language to provide pairing-based confidentiality protocols as smart contracts, verified whether the pairing functions work correctly and compared the proposed pairing functions with the existing method for pairing computation on Ethereum. In addition, using the pairing functions, we implemented the BLS signature scheme as smart contracts and executed them on Ethereum, confirming that the implemented pairing functions can be effectively applied to practical applications.

이더리움은 블록체인 상의 데이터를 모든 참가자가 접근할 수 있는 공개형 블록체인이기 때문에 스마트 컨트랙트로 개인정보 등의 민감한 데이터를 처리하기가 근본적으로 어렵다. 이를 해결하기 위해서 데이터에 대한 기밀성 보장 프로토콜을 스마트 컨트랙트로 구현하는 것을 고려할 수 있고, 대표적인 기밀성 보장 프로토콜로 zkSNARKs와 함수암호가 있다. 기밀성 보장 프로토콜들은 대부분 페어링을 기반 암호연산으로 사용하기 때문에 기밀성 보장 프로토콜들을 스마트 컨트랙트로 구현하기 위해서는 페어링의 구현이 선행되어야 한다. 본 논문에서는 페어링 기반 프로토콜들을 스마트 컨트랙트로 구현하기 위해 필요한 페어링 함수를 Solidity 언어로 구현하고 평가한다.

Block Chain is a technology that records and shares distributed ledgers without a central authority, providing a decentralized platform for transparent transactions in the business and enhancing transparency and traceability in all transactions to ensure trust in the transaction. Despite initial doubts about this technology, it is committed to adopting, adapting and improving the technology in a wide range of industries, including finance, government, security, logistics, food, medical, legal, and real estate. This study examines this technology, its applicability and potential benefits to the manufacturing supply chain. A tracking system of manufacturing supply chain to visualize transparency and traceability is implemented, and the conditions for adopting the technology in the manufacturing supply chain and the issues to be addressed are discussed.

노인의 자녀관계의 영향에 대한 연구는 대부분이 자녀결속력에 초점을 두고 있다. 본 연구는 노인의 자녀와의 관계가 우울 및 삶의 만족도에 미치는 영향을 조사한 것으로 자녀결속력 뿐 아니라 자녀에 대한 부양의무기대, 부모역할만족도 등이 독립변인으로 사용되었다. 또한 노인을 전기노인과 후기노인으로 나누어 연령대에 따른 자녀관련변인의 차이 및 배우자유무에 따른 자녀관련변인의 차이를 검증하였다. 본 연구의 대상은 대구, 경북지역의 노인 237명이며 연령 및 배우자유무에 따른 자녀관련변인의 차이를 비교하기위해 t-test와 카이자승검증을 하였다. 자녀관련변인의 우울과 삶의 만족도에 대한 영향을 파악하기 위해서는 위계적 회귀분석을 각각 사용하였으며 자녀관련변인의 영향정도를 파악하기위해서는 표준화계수인 β를 사용하였다. 회귀분석시 선행연구에 의해 우울과 삶의 만족도에 중요한 영향을 미치는 성별, 배우자유무, 교육수준, 인지건강, 주관적 생활수준 등이 통제변인으로 사용되었다. 연구결과에 의하면 자녀수와 우울은 후기노인이 전기노인보다 유의미하게 높은 것으로 나타났다. 배우자가 있는 노인이 배우자가 없는 노인보다 부모역할만족도가 유의미하게 높게 나타났고 우울은 낮으며 삶의 만족도는 높은 것으로 나타났다. 부모의 역할만족도는 우울을 유의미하게 낮추며 삶의 만족도를 유의미하게 높이고 있다. 그러나 자녀수는 우울을 유의미하게 낮추고 있으며 자녀의 부양의무기대가 높을수록 삶의 만족도는 높은 것으로 나타났다.

Most research about the effect of adult children's family relations focus on the intergenerational solidity. This study examines not only the effect of the intergenerational solidity but also parental expectation about filial responsibility and the satisfaction of parental role on depressive symptoms and life satisfaction. The sample size of this study is 237. To check the difference by age and marital status, t-tests and χ2 were used. To test the effects of adult children's variables about depressive symptoms and life satisfaction, separate hierarchical multiple regressions were used. When using hierarchical multiple regressions, gender, marital status, perceived health and perceived economic status which are important factors of depressive symptoms and life satisfaction are controlled. The research results indicate that there are statistically significant differences between the number of children and depressive symptoms by age. Also, there are statistically significant differences between parental role satisfaction, depressive symptoms and life satisfaction by marital status. The parental role satisfaction affects the depressive symptoms negatively and affects the life satisfaction positively. However, the number of the children only affects the depressive symptom negatively in a statistically significant level. Also, parental expectation of filial responsibility affects the life satisfaction in a statistically significant level.

Recently the blockchain technology has been actively studied due to its great potentiality. The smart contract is a key mechanism of the blockchain system. Due to the short history of the smart contract, many issues have not been solved yet. One main issue is vulnerability and another main issue is cost optimization. While the vulnerability of smart contract has been actively studied, the cost optimization has been rarely studied. In this paper, we propose two cost optimization methods for smart contracts running on the blockchain system. Triggering a function in a smart contract program code may require costs and it is repeated continuously. So the minimization of costs required to trigger a function of smart contract while maintaining the performance equally is very important. The proposed two methods minimize the usage of expensive permanent variables deployed on the blockchain system. We apply the proposed two methods to three prevalent blockchain platforms: Ethereum, Klaytn and Tron. Evaluation experiments verify that the proposed scheme significantly reduces the costs of functions in the smart contract written with Solidity.

As the second part of the author's study, off-design behavior of the design and performance parameters in the low-solidity cascade diffuser in a centrifugal compressor is investigated. The experimental flange-to-flange compressor map serves the validity of application of the present CFD work to the detailed investigation of the low-solidity cascade diffuser. Some meanline design and performance parameters as well as three-dimensional internal secondary flow fields are studied when the flow rate is changed from deep choke to stall.

The primary goal of the current study was to examine category solidity of Korean alveolar fricatives in the Busan and Seoul dialects of Korean. Considering the common belief of $/s^h/-/s^*/$ neutralization in Kyungsang speech, plain $/s^h/$ and fortis $/s^*/$ fricatives of Busan speakers were examined against the same fricatives of Seoul speakers. Perceptual distance between Korean $/s^h/$ and $/s^*/$ on the one hand and English /s/ on the other was investigated by use of across-linguistic mapping method. Two experiments of a perceptual mapping task of English /s/ to Korean $/s^h/$ and $/s^*/$ and a $/s^*/$-production task were conducted on users of the Busan and Seoul dialects of Korean. The results from the perception and production experiments suggested that at a micro-level, younger Busan speakers have less solid category stability for Korean $/s^*/$ compared with Seoul speakers, although their production of $/s^h/$ and $/s^*/$ was as highly distinctive from each other as that of Seoul speakers.

PURPOSE: This study find out the effect of torque and power through various solidity of mouth guard on shoulder flexion and extension. METHODS: This study was conducted with healthy adults in their 20s Korean. Cybex system was used to measure the torque and power fo shoulder joint flexion/extension during isokinetic contraction when the various solidity mouth guard was used and no mouth guard was used. RESULT: The results of this study were summarized as follows: relative torque and average power was showed significantly difference between non applying mouth guard and applying hard type mouth guard during shoulder flexion and extension at isokinetic contraction. CONCLUSION: The application of hard type mouth guard was increased torque and power in joint of body. which may be clinically useful.

The design of low-solidity vaned diffusers and the effect on the performance of a turbocharger compressor is discussed. The effect of vane number and turning angle was investigated while maintaining a basic design with a leading edge angle of $70^{\circ}$, leading and trailing edge radius ratios of 1.1 and 1.3. All results are compared with those obtained with the standard vaneless diffuser configuration and it was shown that all designs increased and shifted the pressure ratio to reduced flowrates. Despite the low-solidity configuration none of the vane designs provided a broad operating range, and the vane leading edge angle was not main factor that system went into the surge condition. The diffuser of higher trailing edge angle improved the flow range for the compressor to operate at lower flow region.