• 설비공학논문집
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• 제22권5호
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• pp.328-335
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• 2010

The purpose of this study is to make an analysis of influence on the cooling capacity and COP of a desiccant cooling system with a regenerative evaporative cooler when a direct evaporative cooler was applied to the inlet of regeneration process of this system. We used cycle simulation in order to analyze the performance of this system. From the cycle simulation, we knew that the optimal rotation time of desiccant rotor was between 160s and 220s and hardly ever affected cooling capacity of desiccant cooling system when this system was operated at the outdoor air condition of $35^{\circ}$ and 40% RH and low regeneration temperature of $60^{\circ}$. Also there was optimal area ratio of regeneration to dehumidification between 0.7 and 1.0. Our results showed that it had a small effect on the system’s cooling capacity to install direct evaporative cooler at the inlet of regeneration process.

• Journal of Power Electronics
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• 제4권4호
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• pp.237-245
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• 2004

In this paper, a two-switch high frequency flyback transformer linked zero voltage soft switching PWM DC-DC power converter implemented for distributed DC- feeding power conditioning supplies is proposed and discussed. This switch mode power converter circuit is mainly based on two main active power semiconductor switches and a main flyback high frequency transformer linked DC-DC converter in which, two passive lossless quasi-resonant snubbers with pulse current regeneration loops for energy recovery to the DC supply voltages composed of a three winding auxiliary high frequency pulse transformer, auxiliary capacitors and auxiliary diodes for inductive energy recovery discharge blocking due to snubber capacitors are introduced to achieve zero voltage soft switching from light to full load conditions. It is clarified that the passive resonant snubber-assisted soft switching PWM DC-DC power converter has some advantages such as simple circuit configuration, low cost, simple control scheme, high efficiency and lowered noises due to the soft switching commutation. Its operating principle is also described using each mode equivalent circuit. To determine the optimum resonant snubber circuit parameters, some practical design considerations are discussed and evaluated in this paper. Moreover, through experimentation the practical effectiveness of the proposed soft switching PWM DC-DC power converter using IGBTs is evaluated and compared with a hard switching PWM DC-DC power converter.

• 한국태양에너지학회 논문집
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• 제27권3호
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• pp.37-44
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• 2007

For the past few years, the concern for clean energy has been greatly increased. Ocean Thermal Energy Conversion(OTEC) power plants are studied as a viable option for the supply of clean energy. In this paper, the thermodynamic performance of OTEC cycle was examined. Computer simulation programs were developed under the same condition and various working fluids for closed Rankine cycle, regeneration cycle, Kalina cycle, open cycle and hybrid cycle. The results show that the regeneration cycle using R125 showed a 0.17 to 1.56% increase in energy efficiency, and simple Rankine cycle can generate electricity when the difference in warm and cold sea water inlet temperatures are greater than $15^{\circ}C$. Also, the cycle efficiency of OTEC power plant using the condenser effluent from nuclear power plant instead of the surface water increased about 2%.

• 융복합기술연구소 논문집
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• 제1권1호
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• pp.41-47
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• 2011

With the world-wide demand on the emission minimization, the needs on the diesel aftertreatment devices with high efficiency are also increasing. In order to effectively develop or design a high-performance diesel particulate filter, a clear understanding on the deposition and regeneration mechanism is required. In the present study, a theory on the lumped parameter model for wall-flow type diesel particulate filters is described focusing on the deposition efficiency, pressure drop inside the filter. The fourth order explicit Runge-Kutta method is utilized for the mass flow rate computation. Engine operation modes with controlled and uncontrolled regeneration options are selected. The computational lumped parameter model is validated by comparing the computed results with the measured data.

• Medical Lasers
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• 제10권1호
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• pp.15-21
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• 2021

As technology advances at a rapid rate, innovations in regenerative medicine will eventually include the use of energy-based therapeutics, such as low intensity-pulsed ultrasound stimulation (LIPUs), pulsed electromagnetic field stimulation (PMFs), and low-level laser/light therapy (LLLt) or photobiomodulation therapy (PBMt). Among these treatments, LLLt/PBMt attracted significant attention by the turn of the century, as evidenced by the numerous publications compared to LIPUs and PMFs, particularly for augmented bone regeneration (ABR). This is a testament of how the maturation of technology and scientific knowledge leads to latent compounded applications, even when the value of a technique is reliant on empirical data. This article reviews some of the notable investigations using LLLt/PBMt for bone regeneration published in the past decade, focusing on how this type of therapy has been utilized together with the existing regenerative medicine landscape.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 1996년도 춘계학술발표회 초록집
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• pp.157-160
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• 1996

• The Journal of Advanced Prosthodontics
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• 제7권6호
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• pp.484-495
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• 2015

PURPOSE. This study was to evaluate the effects of bacterial cellulose (BC) membranes as a barrier membrane on guided bone regeneration (GBR) in comparison with those of the resorbable collagen membranes. MATERIALS AND METHODS. BC membranes were fabricated using biomimetic technology. Surface properties were analyzed, Mechanical properties were measured, in vitro cell proliferation test were performed with NIH3T3 cells and in vivo study were performed with rat calvarial defect and histomorphometric analysis was done. The Mann-Whitney U test and the Wilcoxon signed rank test was used (${\alpha}<.05$). RESULTS. BC membrane showed significantly higher mechanical properties such as wet tensile strength than collagen membrane and represented a three-dimensional multilayered structure cross-linked by nano-fibers with 60 % porosity. In vitro study, cell adhesion and proliferation were observed on BC membrane. However, morphology of the cells was found to be less differentiated, and the cell proliferation rate was lower than those of the cells on collagen membrane. In vivo study, the grafted BC membrane did not induce inflammatory response, and maintained adequate space for bone regeneration. An amount of new bone formation in defect region loaded with BC membrane was significantly similar to that of collagen membrane application. CONCLUSION. BC membrane has potential to be used as a barrier membrane, and efficacy of the membrane on GBR is comparable to that of collagen membrane.

• Journal of Plant Biotechnology
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• 제5권1호
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• pp.51-57
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• 2003

Doubled haploids have long been recognized as a valuable tool in plant breeding since it not only offers the quickest method of advancing heterozygous breeding lines to homozygosity, but also increased the selection efficiency over conventional procedures due to better discrimination between genotypes within any one generation. Salt tolerant mutants were obtained in rice the variety, 'Hawsungbyeo', through in vitro mutagenesis of in vitro cultured anther-derived calli. Various doses (30, 50, 70 and 90 Gy) of gamma ray were applied to investigate the effect of radiation on callus formation on medium containing 1% NaCl, green plant regeneration, frequency of selected doubled haploid mutants and of the salt tolerant screen. It was demonstrated that the dose of 30 and 50 Gy gamma rays had significant effects on callus formation, regeneration and selection of salt tolerance. No tolerant lines were obtained from non-mutagenized cultures. From gamma ray irradiated cultures, five tolerant lines ($M_2$generation) at germination stage and 13 tolerant lines ($M_3$genoration) at seedling stage were obtained. The frequency of salt tolerant mutants indicates that anther culture applied in connection with gamma rays is an effective way to improve salt tolerance.

• 한국수소및신에너지학회논문집
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• 제25권2호
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• pp.122-130
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• 2014

Attrition characteristics of WGS catalysts for pre-combustion $ CO_2$ capture were investigated to check attrition loss of those catalysts, to check change of particle size distribution during attrition tests, and to determine solid circulation direction of WGS catalysts in a SEWGS system. The cumulative attrition losses of two catalysts increased with increasing time. However, attrition loss under humidified condition was lower than that under non-humidified condition case for long-term attrition tests. Between two catalysts, attrition loss of PC-29 catalyst was higher than that of commercial catalyst for long-term attrition tests. However, the commercial catalyst generated much more fines than PC-29 catalyst during attrition. Therefore, we conclude that the PC-29 catalyst is more suitable for fluidized bed operation if we take into account the separation efficiency of cyclone. Based on the results from the tests for the effect of humidity on the attrition loss, we selected solid circulation direction from SEWGS reactor to regeneration reactor because the SEWGS reactor contains more water vapor than regeneration reactor.

• 한국해양환경ㆍ에너지학회지
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• 제17권2호
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• pp.116-121
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• 2014

지열수를 온열원으로 사용하고, 해양심층수를 열침으로 사용하는 바이너리(binary) 지열 발전시스템은 기존 지열 발전시스템의 효율을 증대하기 위한 재열과정과 터빈출력을 향상시키기 위한 다단과정을 각각 또는 복합적으로 적용하여 다단재열재생사이클의 성능개선을 검토하였다. 사이클종류는 다단재열사이클(Multi Stage reheater cycle; MS), 다단재열재생사이클(Multi stage reheater regeneration cycle; MSR)이 있다. 작동유체는 R134a, R245fa를 적용하였으며 온열원의 온도가 $65^{\circ}C$, $75^{\circ}C$, $85^{\circ}C$ 열침은 $5^{\circ}C$를 적용하여 기본해석을 수행하였다. 본 논문에서는 온열원변화, 작동유체의 종류, 사이클의 종류에 따른 해양지열발전용 다단재열재생사이클의 출력 및 효율을 높이기 위한 해석을 수행하였다. 이를 열역학적 사이클로 모사하기 위한 상용 프로그램인 Aspen HYSYS(V8.0)를 이용하여 해석을 진행 하였다. 작동유체는 R245fa가 R134a보다 우수한 성능을 보였으며, 온열원의 변화와 각각의 사이클 종류에 따라 적절한 작동유체가 있음을 확인 할 수 있었다. 사이클의 출력 및 효율은 각각 MS사이클과 MSR사이클에서 좋은 성능을 나타냈다.