전자유체의 차원에 따른 임계온도의 변화

박성훈,김미연,최동식,김원수,Park, Seong-Hun,Kim, Mi-Yeon,Chair, Tong-Seek,Kim, Won-Soo 대한화학회 1996 대한화학회지 Vol.40 No.6

In general, the high temperature superconductors have two-dimensional anisotropic structures. It is important to investigate the dependence of the critical temperature on the dimensions of the electron's motion. The equation of state for electron gas is deduced which describes the electron's motion in superconductors using the kinetic theory of gas. And the critical temperatures of three, two, and one dimensional gases were calculated. According to these equations, restricting the dimension of the electron's motion induces the increase of the critical temperatures. This implies the possibility that the multi-critical temperature of some superconductors is caused by the change of the dimension related to the pathways of the electron. 일반적으로 고온 초전도체들은 2차원적인 구조를 가지고 있으며, 2차원적인 구조가 초전도 물성과 어떠한 관계를 갖는가를 이해하는 것은 매우 중요하다. 본 논문에서는 초전도체 속의 전자기체를 기체분자운동론을 사용하여 각 차원에서의 상태 방정식을 유도하였으며, 그 기체가 액화될 때의 온도, 임계온도를 구하였다. 그 결과 전자의 자유도를 제한시킴에 따라 임계온도가 상승함을 알 수 있었다. 이것은 2차원적인 구조물질에 1차원적인 전자유통 경로가 있을 경우 여러가지의 임계온도를 가질 수 있음을 의미한다.

소형화와 저전력화를 위해 2M-byte on-chip SRAM과 아날로그 회로를 포함하는 SoC

박성훈,김주언,백준현,Park, Sung Hoon,Kim, Ju Eon,Baek, Joon Hyun 한국전기전자학회 2017 전기전자학회논문지 Vol.21 No.3

Based on several CPU cores, an SoC including ADCs, DC-DC converter and 2M-byte SRAM is proposed in this paper. The CPU core consists of a 12-bit MENSA, a 32-bit Symmetric multi-core processor, as well as 16-bit CDSP. To eliminate the external SDRAM memory, internal 2M-byte SRAM is implemented. Because the SRAM normally occupies huge area, the parasitic components reduce the speed of SoC. In this work, the SRAM blocks are divided into small pieces to reduce the parasitic components. The proposed SoC is developed in a standard 55nm CMOS process and the speed of SoC is 200MHz. 다종의 CPU를 기반으로 ADC와 DC-DC 변환기를 포함하며 2M-byte의 SRAM이 내장된 SoC가 제안되었다. CPU 코어는 12-bit MENSA 코어, 32-bit Symmetric Multi-core 프로세서, 16-bit CDSP로 구성된다. 외부 SDRAM 메모리를 제거하기 위해 내부의 2M-byte SRAM을 설계하였으나 SRAM 블록들이 넓은 영역에 분포하여 기생 성분에 의해 속도가 저하되므로 SRAM을 작게 분할하여 레이아웃 하였다. 설계된 SoC는 55nm 공정으로 개발되었으며 속도는 200MHz이다.

비동기적 분산 시스템에서 선출 문제는 NF-completeness 문제임을 증명

박성훈,Park, Sung-Hoon 한국정보과학회 2002 정보과학회논문지 : 시스템 및 이론 Vol.29 No.3

본 논문은 프로세스들이 크래시(crash)되어 죽을 수 있으나 통신망은 신뢰 할 수 있는 비동기적 분산 시스템에서 선출(election) 문제 해결의 어려움에 대하여 논한 글이다. 비동기적인 분산 시스템에서 문제들을 해결하는데 어려움의 정도는 프로세스들의 실패(failure)에도 불구하고 그것들을 해결 할 수 있느냐 하는 어려움(difficulty)에 의해 결정된다. 비동기적인 분산 시스템에서 부딪치는 문제들은 3부류의 문제들로 구분되는 바: F(고장 감내), NF(비고장 감내), NFC(비고장 감내 완전성)의 3 종류들이다. 그런 문제들 중, NFC 부류의 문제들이 해결하기 가장 어려운 문제들이다. 본 논문에서는 선출 문제도 NFC 부류에 속하는 해결하기 가장 어려운 문제임을 증명한다. This paper is about the hardness of the Election problem in asynchronous distributed systems in which processes can crash but links are reliable. The hardness of the problem is defined with respect to the difficulty to solve it despite failures. It is shown that problems encountered in the system are classified as three classes of problems: F (fault-tolerant), NF (Not fault-tolerant) and NFC(NF-completeness). Among those, the class NFC is the hardest problems to solve. In this paper, we prove that the Election problem is the most difficult problem which belongs to the class NFC.

A Simple Parameterization for the Rising Velocity of Bubbles in a Liquid Pool

박성훈,Changhwan Park,JinYong Lee,Byungchul Lee 한국원자력학회 2017 Nuclear Engineering and Technology Vol.49 No.4

The determination of the shape and rising velocity of gas bubbles in a liquid pool is of great importance in analyzing the radioactive aerosol emissions from nuclear power plant accidents in terms of the fission product release rate and the pool scrubbing efficiency of radioactive aerosols. This article suggests a simple parameterization for the gas bubble rising velocity as a function of the volume-equivalent bubble diameter; this parameterization does not require prior knowledge of bubble shape. This is more convenient than previously suggested parameterizations because it is given as a single explicit formula. It is also shown that a bubble shape diagram, which is very similar to the Grace's diagram, can be easily generated using the parameterization suggested in this article. Furthermore, the boundaries among the three bubble shape regimes in the Eo-Re plane and the condition for the bypass of the spheroidal regime can be delineated directly from the parameterization formula. Therefore, the parameterization suggested in this article appears to be useful not only in easily determining the bubble rising velocity (e.g., in postulated severe accident analysis codes) but also in understanding the trend of bubble shape change due to bubble growth.

대표적인 한국식품의 수출 현황 및 전망

박성훈,Park, Seong-Hun 한국식품연구원 2007 食品技術 Vol.20 No.2

Biohydrogen Production from Carbon Monoxide and Water by Rhodopseudomonas palustris P4

박성훈,오유관,Yu-Jin Kim,Ji-Young Park,Tae Ho Lee,김미선 한국생물공학회 2005 Biotechnology and Bioprocess Engineering Vol.10 No.3

A reactor-scale hydrogen (H2) production via the water-gas shift reaction of carbon monoxide (CO) and water was studied using the purple nonsulfur bacterium, Rhodopseudomonas palustris P4. The experiment was conducted in a two-step process: an aerobic/chemoheterotro-phic cell growth step and a subsequent anaerobic H2 production step. Important parameters investigated included the agitation speed, inlet CO concentration and gas retention time. P4 showed a stable H2 production capability with a maximum activity of 41 mmol H2 g cell-1h-1 during the continuous reactor operation of 400 h. The maximal volumetric H2 production rate was estimated to be 41 mmol H2 L-1h-1, which was about nine-fold and fifteen-fold higher than the rates reported for the photosynthetic bacteria Rhodospirillum rubrum and Rubrivivax gelatinosus, respectively. This is mainly attributed to the ability of P4 to grow to a high cell density with a high specific H2 production activity. This study indicates that P4 has an outstanding potential for a continuous H2 production via the water-gas shift reaction once a proper bioreactor system that provides a high rate of gas-liquid mass transfer is developed.

건설현장배치 수준의 정량적 평가: 사용성평가 방법을 활용하여

박성훈,김태완,손보식,Park, Seonghun,Kim, Tae Wan,Son, Bosik 한국건설관리학회 2022 건설관리 : 한국건설관리학회 학회지 Vol.23 No.5

Construction site layout is attracting attention as efficient use of construction site space greatly affects the duration and cost of the overall construction. Therefore, there are many studies that automate and optimize construction site layout planning. However, the usability of construction site, which consists of goal variables of the studies, has still been unknown. Therefore, the authors present the evaluation criteria for usability of construction site layout and evaluate the usability of domestic construction sites through user survey. Furthermore, the difference in usability between construction site managers and construction site workers was confirmed. As a result of the survey, domestic construction site layout had a low effectiveness and had the lowest score in the environment category. In addition, construction site workers scored lower overall than construction site managers. Through such usability evaluation results, it contributed to the construction site layout theory by assessing current construction site layout practice and suggesting an improvement direction for automating site layout planning.

비동기적 분산 시스템하에서 선출 문제 해결을 위한 최소 필요 조건

박성훈,Park, Sung-Hoon 한국정보처리학회 2000 정보처리논문지 Vol.7 No.12

본 논문에서는 비동기적 분산 시스템에서 산출(Election) 문제를 해결하는데 필요한 최소한의 조건에 대해 논하고자 한다. 이 논문의 핵심은 비동기적 분산 시스템에서 산출 문제를 해결하는데 가장 약한 고장 추적장치는 무엇인가를 찾아내는 데 있다. 먼저 비동기적 분산 시스템에서 산출 문제와 합의(Consensus)문제에 대한 관련성을 토의하고 선출 문제는 합의 문제보다 더욱 어려운 문제임을 보인다. 보다 엄밀하게 표현하자면, 선출 문제를 해결하는데 필요한 가장 약한 고장 추적 장치는 완전한 고장 추적 장치이어야 하는 것으로, 이는 합의 문제를 해결하는데 필요한 가장 약한 고장 추적 장치보다 확실히 강한 것이다. This paper is about the minimum requirements to solve the Election problem in asynchronous distributed systems. The focus of the paper is to find out what failure detector is the weakest one to solve the Election problem. We first discuss the relationship between the Election problem and the Consensus problem in asynchronous distributed systems with unreliable failure detectors and show that the Election problem is harder than the Consensus problem. More precisely, the weakest failure detector that is needed to solve this problem is a Perfect Failure Detector. which is strictly stronger than the weakest failure detector that is needed to solve Consensus.

대표적인 한국식품의 수출 현황 및 전망

박성훈,Park, Seong-Hun 한국식품산업협회 2007 좋은식품 Vol.197 No.-

대표적인 한국식품의 수출 현황 및 전망

박성훈,Park, Sung-Hoon 한국식품영양과학회 2007 식품산업과 영양 Vol.12 No.1