• 대한기계학회논문집
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• 제10권2호
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• pp.215-222
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• 1986

본 연구에서는 디이젤기관의 연소특성식계산에 기초가 되는 실린더내의 압력 을 구하고, 압력상승율과 열발생율을 실험식와 비교검토하고, 실린더내의 최고압력 및 압력상승율의 출현빈도분포를 구하였다.

• 대기
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• 제24권4호
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• pp.457-470
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• 2014

Thermodynamic conditions related with localized torrential rainfall in the middle west region of Korean peninsula are examined using radar rain rate and radiosonde observational data. Localized torrential rainfall events in this study are defined by three criteria base on 1) any one of Automated Synoptic Observing System (ASOS) hourly rainfall exceeds $30mmhr^{-1}$ around Osan, 2) the rain (> $1mmhr^{-1}$) area estimated from radar reflectivity is less than $20,000km^2$, and 3) the rain (> $10mmhr^{-1}$) cell is detected clearly and duration is short than 24 hr. As a result, 13 cases were selected during the summer season of 10 years (2004-13). It was found that the duration, the maximum rain area, and the maximum volumetric rain rate of convective cells (> $30mmhr^{-1}$) are less than 9hr, smaller than $1,000km^2$, and $15,000{\sim}60,000m^3s^{-1}$ in these cases. And a majority of cases shows the following thermodynamic characteristics: 1) Convective Available Potential Energy (CAPE) > $800Jkg^{-1}$, 2) Convective Inhibition (CIN) < $40Jkg^{-1}$, 3) Total Precipitable Water (TPW) ${\approx}$ 55 mm, and 4) Storm Relative Helicity (SRH) < $120m^2s^{-2}$. These cases mostly occurred in the afternoon. These thermodynamic conditions indicated that these cases were caused by strong atmospheric instability, lifting to overcome CIN, and sufficient moisture. The localized torrential rainfall occurred with deep moisture convection result from the instability caused by convective heating.

• Journal of Acupuncture Research
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• 제21권6호
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• pp.233-248
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• 2004

Objective : The purpose of this study is to investigate the mechanism and effect of moxibustion with monkshood cake, slice & black pepper cake. objectively, to be used as the quantitative data through the measurement of temperatqre, and to grasp the thermodynamic characteristics of moxibustion with monkshood cake, slice & black pepper cake. Methods : We have selected of the moxibustion with monkshood cake, slice & black pepper cake. indirect moxibustion. We make a comparative study of the thermodynamic characteristics of moxibustion with monkshood cake, slice & black pepper cake. We examined combustion times, temperatures, temperature gradients in each period during a combustion of moxa. Results & Conclusions : 1. We can design the moxibustion with monkshood cake that it has thermodynamic characteristics of 173sec effective combustion time, $44^{\circ}C$ maximum temperature, $0.22^{\circ}C/sec$ ascending maximum temperature, if we use 3mm thickness or 3mm and below of monkshood cake and the moxa cone is formed the conical shape that the base diameter was 8mm, the height was 10mm, the density was $600mg/cm^3$. 2. We can design the moxibustion with monkshood cake that it has thermodynamic characteristics of 205~271sec effective combustion period time, $44.6{\sim}46.1^{\circ}C$ maximum temperature, $0.18{\sim}0.24^{\circ}C/sec$ ascending maximum temperature, if we use 3mm thickness of monkshood cake and the moxa cone is formed the conical shape that the base diameter was 8mm, the height was 10mm, the density was $480{\sim}720mg/cm^3$.

• 한국수소및신에너지학회논문집
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• 제24권6호
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• pp.510-517
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• 2013

The ammonia-water based power generation cycle utilizing liquefied natural gas (LNG) as its heat sink has attracted much attention, since the ammonia-water cycle has many thermodynamic advantages in conversion of low-grade heat source in the form of sensible energy and LNG has a great cold energy. In this paper, we carry out thermodynamic performance analysis of a combined power generation cycle which is consisted of an ammonia-water regenerative Rankine cycle and LNG power generation cycle. LNG is able to condense the ammonia-water mixture at a very low condensing temperature in a heat exchanger, which leads to an increased power output. Based on the thermodynamic models, the effects of the key parameters such as source temperature, ammonia concentration and turbine inlet pressure on the characteristics of system are throughly investigated. The results show that the thermodynamic performance of the ammonia-water power generation cycle can be improved by the LNG cold energy and there exist an optimum ammonia concentration to reach the maximum system net work production.

• 한국가스학회지
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• 제18권2호
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• pp.41-47
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• 2014

본 논문에서는 유기랭킨사이클과 LNG 사이클로 구성된 복합사이클의 열역학적 성능 해석을 수행한다. 이 복합사이클에서는 현열 형태의 저등급 폐열을 사용하며 LNG 냉열은 열싱크 뿐 아니라 동력 생산에도 사용된다. 시스템의 성능에 대한 터빈입구압력, 응축온도, 열원온도 등 주 파라미터들의 영향을 상세하게 분석한다. 시뮬레이션 결과는 이 복합시스템은 LNG 냉에너지를 사용하지 않은 일반의 ORC에 비해 현저하게 성능이 개선될 수 있음을 보여준다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제51권6호
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• pp.265-270
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• 2002

The determination of DNA hybridization reaction can apply the molecular biology research, clinic diagnostics, bioengineering, environment monitoring, food science and application area. So, the improvement of DNA hybridization detection method is very important for the determination of this hybridization reaction. Several molecular biological techniques require accurate predictions of matched versus mismatched hybridization thermodynamics, such as PCR, sequencing by hybridization, gene diagnostics and antisense oligonucleotide probes. In addition, recent developments of oligonucleotide chip arrays as means for biochemical assays and DNA sequencing requires accurate knowledge of hybridization thermodynamics and population ratios at matched and mismatched target sites. In this study, we report the characteristics of the probe and matched, mismatched target oligonucleotide hybridization reaction using thermodynamic method. Thermodynamic of 5 oligonucleotides with central and terminal mismatch sequences were obtained by measured UV-absorbance as a function of temperature. The data show that the nearest-neighbor base-pair model is adequate for predicting thermodynamics of oligonucleotides with average deviations for $\Delta$H$^{0}$ , $\Delta$S$^{0}$ , $\Delta$G$_{37}$ $^{0}$ and T$_{m}$, respectively.>$^{0}$ and T$_{m}$, respectively.

• 에너지공학
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• 제24권2호
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• pp.79-83
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• 2015

Hydrogen has long been recognized as a fuel having some unique and highly desirable properties, for application as a fuel in engines. Hydrogen has some remarkably high values of the key properties for transport processes, such as kinematic viscosity, thermal conductivity and diffusion coefficient, in comparison to those of the other fuels. Such differences together with its extremely low density and low luminosity help to give hydrogen its unique diffusive and heat transfer characteristics. The thermodynamic and heat transfer characteristics of hydrogen tend to produce high compression temperatures that contribute to improvements in engine efficiency and lean mixture operation.

• 설비공학논문집
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• 제15권9호
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• pp.768-778
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• 2003

Numerical analysis has been carried out to investigate laminar convective heat transfer in a tube for supercritical water near the thermodynamic critical point. Fluid flow and heat transfer are strongly coupled due to large variations of thermodynamic and transport properties such as density, specific heat, viscosity, and thermal conductivity near the critical point. Heat transfer characteristics in the developing region of the tube show transition behavior between liquid-like and gas-like phases with a peak in heat transfer coefficient distribution near the pseudocritical point. The peak of the heat transfer coefficient depends on pressure and wall heat flux rather than inlet temperature and Reynolds number, Results of the modeling provide convective heat transfer characteristics including velocity vectors, temperature, and the properties as well as the heat transfer coefficient. The effect of proximity to the critical point is considered and a heat transfer correlation is suggested for the peak of Nusselt number in the tube.

• International Journal of Air-Conditioning and Refrigeration
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• 제13권4호
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• pp.206-216
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• 2005

Numerical analysis has been carried out to investigate laminar convective heat transfer at zero gravity in a tube for supercritical water near the thermodynamic critical point. Fluid flow and heat transfer are strongly coupled due to large variation of thermodynamic and transport properties such as density, specific heat, viscosity, and thermal conductivity near the critical point. Heat transfer characteristics in the developing region of the tube show transition behavior between liquid-like and gas-like phases with a peak in heat transfer coefficient distribution near the pseudo critical point. The peak of the heat transfer coefficient depends on pressure and wall heat flux rather than inlet temperature and Reynolds number. Results of the modeling provide convective heat transfer characteristics including velocity vectors, temperature, and the properties as well as the heat transfer coefficient. The effect of proximity on the critical point is considered and a heat transfer correlation is suggested for the peak of Nusselt number in the tube.

• 대기
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• 제34권3호
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• pp.257-271
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• 2024

In 2023, the World Meteorological Organization released a report on climate conditions in Asia, highlighting the region's high vulnerability to floods and the increasing severity and frequency of extreme precipitation events. While previous studies have largely concentrated on broader-scale phenomena such as the Asian monsoon, it is crucial to investigate the substantial characteristics of extreme precipitation for a better understanding. In this study, we analyze the spatiotemporal characteristics of extreme precipitation during summer and their affecting factors by decomposing the moisture budgets within specific Asian regions over 44 years (1979~2022). Our findings indicate that dynamic convergence terms (DY CON), which reflect changes in wind patterns, primarily drive extreme rainfall across much of Asia. In southern Asian sub-regions, particularly coastal areas, extreme precipitation is primarily driven by low-pressure systems, with DY CON accounting for 70% of the variance. However, in eastern Asia, both thermodynamic advection and nonlinear convergence terms significantly contribute to extreme precipitation. Notably, on the Korean Peninsula, thermodynamic advection plays an important role, driven by substantial moisture carried by strong southerly mean flow. Understanding these distinct characteristics of extreme rainfall across sub-regions is expected to enhance both predictability and resilience.