• Title/Summary/Keyword: Energy Efficiency Improvement

Search Result 1,002, Processing Time 0.031 seconds

The Power Converter Circuit Characteristics for 3 kW Wireless Power Transmission (3 kW 무선 전력전송을 위한 전력 변환기 회로 특성)

  • Hwang, Lark-Hoon;Na, Seung-kwon;Kim, Jin Sun;Kang, Jin-hee
    • Journal of Advanced Navigation Technology
    • /
    • v.24 no.6
    • /
    • pp.566-572
    • /
    • 2020
  • In a wireless power transmitter, the characteristics and effects of wireless power transmission between two induction coils are investigated, and a power converter circuit and a battery charger/discharger circuit using wireless power transmission technology are proposed. The advantage of wireless power transmitters and wireless chargers is that, instead of the existing plug-in-mounted wired charger (OBC; on-board charger), the user can wirelessly charge the battery without connecting the power source when charging power to the battery. There is. In addition, the advantage of wireless charging can bring about an energy efficiency improvement effect by using the secondary side rectifier circuit and the receiving coil, but the large-capacity long-distance wireless charging method has a limitation on the transmission distance, so many studies are currently being conducted. The purpose of the study is to study the transmitter circuit and receiver circuit of a wireless power transmission device using a primary coil, a secondary coil, and a half bridge series resonance converter, which can transmit power of a non-contact type power transmitter. As a result, a new topology was applied to improve the power transmission distance of the wireless charging system, and through an experiment according to each distance, the maximum efficiency (95.8%) was confirmed at an output of 3 kW at an 8 cm transmission distance.

Countermeasures to the Introduction of Low Caloric Gas Fuel for Natural Gas Engine (저열량 가스 적용에 따른 천연가스엔진의 대응 방안 연구)

  • Park, Cheol-Woong;Kim, Chang-gi;Oh, Se-Chul;Lee, Jang-Hee
    • Journal of the Korean Institute of Gas
    • /
    • v.25 no.2
    • /
    • pp.34-41
    • /
    • 2021
  • In order to cope with the problems that may occur when the natural gas used in Korea becomes low in calories, the problems that may have to the domestic industrial gas equipment must be identified in advance, and based on this, countermeasures for efficient use of energy must be preceded. In this study, in order to solve the problem of deterioration of engine output performance and efficiency due to the introduction of low calorific gas when using a lean-burning natural gas engine that complies with the EURO-6 regulation, specific control plans and results based on the experiment are intended to be presented. In order to identify the improvement effect by the control variable represented by the ignition timing under the full load condition at the engine speed of 1,400 rpm and 550 Nm, 2,100 rpm, which is the engine speed at the rated operation condition, the thermal efficiency and exhaust gas characteristics were identified and optimized by changing the ignition timing for each gas fuel. In the case of pure methane, which shows the lowest value based on the torque under the full load condition, if the ignition timing is advanced by about 2 CAD from the reference ignition timing, the torque can be compensated without a large increase in NOx emission.

Study on the Biofouling Management of International Ships Entering South Korea (국내입항 국제운항선의 선체부착생물 관리에 대한 연구)

  • Park, JeongKyeong;Hoe, ChulHoi;Kim, HanPil;Cho, YuKyeong
    • Journal of the Korean Society of Marine Environment & Safety
    • /
    • v.28 no.1
    • /
    • pp.10-18
    • /
    • 2022
  • With the increase in world trade through ships, the destruction of the marine ecosystem and socioeconomic damage due to invasive alien species (IAS) are continuously increasing. In particular, marine organisms attached on the hull surface and niche area increase the friction resistance of ships as well as the invasion of non-indigenous species, and causes a decrease in operational efficiency and an increase in GHG (Green House Gas) emissions. The International Maritime Organization (IMO) has recently begun revising guidelines for the control and management of ship's biofouling, and New Zealand and California in the United States are already regulating biofouling management under their own laws. This study investigated the management status of the submerged surface of ships and marine organisms attachments on five international ships entering South Korea, and analyzed species group and coverage (%) of biofouling communities to evaluate the LoF (Level of Fouling) rank. Macroflouling was observed on all ships surveyed, and specially, the adhesion of macro organisms in niche areas such as bow thruster, bilge keels and sea-chest gratings appeared to be at a serious level. This study proposed the management direction our country should take with regard to ship's biofouling and the improvement measures for evaluation of LoF rank and inspection methods of hull and niche ares.

Relationships between dietary rumen-protected lysine and methionine with the lactational performance of dairy cows - A meta-analysis

  • Agung Irawan;Ahmad Sofyan;Teguh Wahyono;Muhammad Ainsyar Harahap;Andi Febrisiantosa;Awistaros Angger Sakti;Hendra Herdian;Anuraga Jayanegara
    • Animal Bioscience
    • /
    • v.36 no.11
    • /
    • pp.1666-1684
    • /
    • 2023
  • Objective: Our objective was to examine the relationships of supplemental rumen-protected lysine (RPL) or lysine + methionine (RPLM) on lactational performance, plasma amino acids (AA) concentration, and nitrogen use efficiency of lactating dairy cows by using a meta-analysis approach. Methods: A total of 56 articles comprising 77 experiments with either RPL or RPLM supplementation were selected and analyzed using a mixed model methodology by considering the treatments and other potential covariates as fixed effects and different experiments as random effects. Results: In early lactating cows, milk yield was linearly increased by RPL (β1 = 0.013; p<0.001) and RPLM (β1 = 0.014; p<0.028) but 3.5% fat-corrected milk (FCM) and energy-corrected milk (ECM) (kg/d) was increased by only RPL. RPL and RPLM did not affect dry matter intake (DMI) but positively increased (p<0.05) dairy efficiency (Milk yield/DMI and ECM/DMI). As a percentage, milk fat, protein, and lactose were unchanged by RPL or RPLM but the yield of all components was increased (p<0.05) by feeding RPL while only milk protein was increased by feeding RPLM. Plasma Lys concentration was linearly increased (p<0.05) with increasing supplemental RPL while plasma Met increased (p<0.05) by RPLM supplementation. The increase in plasma Lys had a strong linear relationship (R2 = 0.693 in the RPL dataset and R2 = 0.769 in the RPLM dataset) on milk protein synthesis (g/d) during early lactation. Nitrogen metabolism parameters were not affected by feeding RPL or RPLM, either top-dress or when supplemented to deficient diets. Lactation performance did not differ between AA-deficient or AA-adequate diets in response to RPL or RPLM supplementation. Conclusion: RPL or RPLM showed a positive linear relationship on the lactational performance of dairy cows whereas greater improvement effects were observed during early lactation. Supplementing RPL or RPLM is recommended on deficient-AA diet but not on adequate-AA diet.

Improvement of Cu2ZnSnS4 Solar Cell Characteristics with Zn(Ox,S1-x) Buffer Layer (Zn(Ox,S1-x) 버퍼층 적용을 통한 Cu2ZnSnS4 태양전지 특성 향상)

  • Yang, Kee-Jeong;Sim, Jun-Hyoung;Son, Dae-Ho;Lee, Sang-Ju;Kim, Young-Ill;Yoon, Do-Young
    • Korean Chemical Engineering Research
    • /
    • v.55 no.1
    • /
    • pp.93-98
    • /
    • 2017
  • This experiment investigated characteristic changes in a $Cu_2ZnSnS_4$(CZTS) solar cell by applying a $Zn(O_x,S_{1-x})$ butter layer with various compositions on the upper side of the absorber layer. Among the four single layers such as $Zn(O_{0.76},S_{0.24})$, $Zn(O_{0.56},S_{0.44})$, $Zn(O_{0.33},S_{0.67})$, and $Zn(O_{0.17},S_{0.83})$, the $Zn(O_{0.76},S_{0.24})$ buffer layer was applied to the device due to its bandgap structure for suppressing electron-hole recombination. In the application of the $Zn(O_{0.76},S_{0.24})$ buffer layer to the device, the buffer layer in the device showed the composition of $Zn(O_{0.7},S_{0.3})$ because S diffused into the buffer layer from the absorber layer. The $Zn(O_{0.7},S_{0.3})$ buffer layer, having a lower energy level ($E_V$) than a CdS buffer layer, improved the $J_{SC}$ and $V_{OC}$ characteristics of the CZTS solar cell because the $Zn(O_{0.7},S_{0.3})$ buffer layer effectively suppressed electron-hole recombination. A substitution of the CdS buffer layer by the $Zn(O_{0.7},S_{0.3})$ buffer layer improved the efficiency of the CZTS solar cell from 2.75% to 4.86%.

Performance Improvement of Computing Time of 2 Dimensional Finite Volume Model using MPI (MPI를 이용한 2차원 유한체적모형의 계산 성능 개선)

  • Kim, Tae Hyung;Han, Kun Yeun;Kim, Byung Hyun
    • Journal of Korea Water Resources Association
    • /
    • v.47 no.7
    • /
    • pp.599-614
    • /
    • 2014
  • In this study, two dimensional finite volume model was parallelized to improve computing time, which has been developed to be able to apply for the mixed meshes of triangle and quadrilateral. MPI scheme which is free from limitation of the number of cores was applied, and non-blocking point-to-point communication was used for fluxes and time steps calculation domain. The developed model is applied to analyze dam break in a L-shaped experimental channel with $90^{\circ}$ bend and Malpasset dam breach event to calibrate the consistency between parallelized model and existing model and examine the speed-up and efficiency of computing time. Computational speed-up about the size of the input data was considered by simulating 4 cases classified by the number of meshes, Consequently, the simulation results reached a satisfactory accuracy compared to measured data and the results from existing model, and achieved more than 3 times benefit of computational speed-up against computing time of existing model. Simulation results of 3 cases classified by the size of input data lead us to the conclusion that it is important to use proper size of input data and the number of process in order to minimize the communication overhead.

Local Grid-based Multipath Routing Protocol for Mobile Sink in Wireless Sensor Networks (무선 센서 네트워크에서 이동 싱크를 지원하기 위한 지역적 격자 기반 다중 경로 전송 방안)

  • Yang, Taehun;Kim, Sangdae;Cho, Hyunchong;Kim, Cheonyong;Kim, Sang-Ha
    • Journal of KIISE
    • /
    • v.43 no.12
    • /
    • pp.1428-1436
    • /
    • 2016
  • A multipath routing in wireless sensor networks (WSNs) provides advantage such as reliability improvement and load balancing by transmitting data through divided paths. For these reasons, existing multipath routing protocols divide path appropriately or create independent paths efficiently. However, when the sink node moves to avoid hotspot problem or satisfy the requirement of the applications, the existing protocols have to reconstruct multipath or exploit foot-print chaining mechanism. As a result, the existing protocols will shorten the lifetime of a network due to excessive energy consumption, and lose the advantage of multipath routing due to the merging of paths. To solve this problem, we propose a multipath creation and maintenance scheme to support the mobile sink node. The proposed protocol can be used to construct local grid structure with restricted area and exploit grid structure for constructing the multipath. The grid structure can also be extended depending on the movement of the sink node. In addition, the multipath can be partially reconstructed to prevent merging paths. Simulation results show that the proposed protocol is superior to the existing protocols in terms of energy efficiency and packet delivery ratio.

A Study on the Causal Relationship Between Electricity Consumption and Output in Manufacturing Sectors of Korea (국내 제조업종별 전력소비와 경제산출간 인과관계 분석)

  • Park, Min Hyuk
    • KEPCO Journal on Electric Power and Energy
    • /
    • v.3 no.1
    • /
    • pp.65-72
    • /
    • 2017
  • This study analyzed causal relationship between electricity consumption and economic output (GDP) for Korea from 2001 to 2014 employing the vector error-correction model estimation by manufacturing sector. The results of unit-roots tests show that all sectoral GDP and electricity consumptions were not stationary. And cointegration tests show that processed foods, Wood Pulp Paper, electricity apparatus, Precision Medical sectors had a linear combinations in the long run between electricity consumptions and economic growth. With respect to the direction of causality, manufacturing sector has a uni-directional running from economic output (GDP) to electricity consumption in short term. The results of study show that sectoral causal relation were different each other in short term and long term. These findings imply that electricity demand management policy focusing on efficiency improvement is necessary to minimize negative impacts on economic growth and to adopt suitable structural policies can induce energy conservation.

A Study on the Monitoring Method of Ship Hull and Propeller Performance by Operating Ship (선체 및 프로펠러 성능 모니터링 방법 실선 적용을 통한 고찰)

  • KIM, Dong-Hyun;JUNG, Bong-Kyu;HAN, Seung-Jae
    • Journal of the Korean Society of Marine Environment & Safety
    • /
    • v.26 no.1
    • /
    • pp.15-21
    • /
    • 2020
  • This study analyzes the results of applying the ISO19030 (hull and propeller performance monitoring method) standard to an actual 178 k bulk vessel. Recently, there have been many attempts to apply various energy reduction solutions to vessels to continuously strengthen GHG reduction regulations and secure maritime competitiveness. However, it is not easy to quantitatively analyze the performance of a ship. To resolve these problems, shipping companies, marine paint companies, ship owners, and transportation associations have appointed specialists and standardized the ISO19030 (standard of hull and propeller performance monitoring method) guidelines in 2016 after three years of continuous review. The ISO19030 standard provides methods to monitor hull and propeller performance quantitatively through standardized procedures, thus allowing ship managers to arrive at informed decisions for hull and propeller maintenance, and to evaluate energy-saving solutions and ship-maintenance efficiency. The ISO19030 standard provides a method of analyzing the ship's own performance by collecting the ship's operation and agency data and correcting its environmental and operating factors. In this paper, we apply the ISO19030 standard to three actual ships and propose the ISO19030 application result and the improvement point of the current ISO19030 standard.

Physical, Morphological, and Chemical Analysis of Fly Ash Generated from the Coal Fired Power Plant (석탄 화력발전소에서 발생되는 석탄회 특성과 형성 분석에 관한 연구)

  • 이정언;이재근
    • Journal of Energy Engineering
    • /
    • v.7 no.1
    • /
    • pp.146-156
    • /
    • 1998
  • Fly ash produced in coal combustion is a fine-grained material consisting mostly of spherical, glassy, and porous particles. A physical, morphological, and chemical characteristic of fly ash has been analyzed. This study may contribute to the data base of domestic fly ash, the improvement of combustion efficiency, ash recycling and ash collection in the electrostatic precipitator. The physical property of fly ash is determined using a particle counter for the measurement of ash size distribution and gravimeter. Morphological characteristic of fly ash is performed using a scanning electron micrograph and an optical microscope. The chemical components of fly ash are determined using an inductively coupled plasma emission spectrometry (ICP). The distribution of fly ash size was ranged from 15 to 25 $\mu$m in mass median diameter. Exposure conditions of flue gas temperature and duration within the combustion zone of the boiler played an important role on the morphological properties of the fly ash such as shape, relative opacity, coloration, cenosphere and plerosphere. The spherical fly ash might be generated at the condition of complete combustion. The size of fly ash was found to be increased the with particle-particle interaction of agglomeration and coagulation. Fly ash consisted of $SiO_2\;Al_2O_3\;and\;Fe_2O_3$ with 85% and carbon with 3~10% of total mass.

  • PDF