• Title/Summary/Keyword: Thermal recovery

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Analysis of the current status and implications of nitrogen recovery from livestock manure (가축분뇨로부터 질소 회수 연구 현황 및 시사점 분석)

  • Im, Seongwon;Kim, Sangmi;Kim, Jimin;Kim, Dong-Hoon
    • Journal of the Korea Organic Resources Recycling Association
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    • v.29 no.1
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    • pp.37-46
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    • 2021
  • Nitrogen and phosphorus in livestock manure are environmental pollutants, but also could be valuable industrial resources. In the present study, we (1) introduced various nitrogen removal technologies such as stripping, thermal method, membrane, and electrodialysis, (2) reviewed relevant studies reported in 2011-2020, in particular, full-scale experiences, and (3) assessed each technologies based on the above survey results. In addition, we provided the information on the appropriate range of the pH, temperature, gas and liquid ratio, and so on in ammonia stripping process, and expected mass balance when it is connected to biogasification process. We hope the content herein can be helpful for making policy and operating full-scale plant in Korea.

Temperature ranges for survival and growth of juvenile Saccharina sculpera (Laminariales, Phaeophyta) and applications for field cultivation

  • Kim, Soo Hong;Kim, Young Dae;Hwang, Mi Sook;Hwang, Eun Kyoung;Yoo, Hyun Il
    • ALGAE
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    • v.36 no.4
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    • pp.231-240
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    • 2021
  • Saccharina sculpera is highly valued for human consumption and value-added products. However, natural resources of this kelp have decreased sharply and it is in danger of extinction. Resources recovery through cultivation is being trialed to enable the sustainable use of this species. In this study, the temperature range for survival and optimal growth of juvenile S. sculpera was identified and applied to field cultivation. This study investigated the survival and growth of juvenile S. sculpera under six temperatures (i.e., 5, 10, 15, 16, 18, and 20℃) and two light intensities (i.e., 20 and 40 µmol photons m-2 s-1) in an indoor culture experiment. In these experiments, the blade length decreased at 16℃ under the both light intensities. The thalli died at 20℃ and 20 µmol photons m-2 s-1, and at 18-20℃ and 40 µmol photons m-2 s-1. During the field cultivation, early growth of S. sculpera was highest at the 5 m depth and growth decreased as the water depth increased. When the initial rearing depth was maintained without adjustment throughout the cultivation period (from December to October), all the cultivated S. sculpera plants died during August and September. However, S. sculpera plants lowered from 5 to 15 m and grew to 90.8 ± 13.1 cm in July. The seawater temperature at 15 m depth was similar to the upper level of thermal tolerance demonstrated by juvenile S. sculpera in the indoor culture experiments (16℃ or lower). The plants were subsequently lowered to 25 m depth in August, which eventually led to their maturation in October. The present study confirmed that improved growth rates and a delay in biomass loss can be achieved by adjusting the depth at which the seaweeds are grown during the cultivation period. These results will contribute to the establishment of sustainable cultivation systems for S. sculpera.

The Effect of Transcranial Direct Current Stimulation on Pain and Balance of Total Knee Arthroplasty Patients (경두개직류전류자극이 무릎관절 전치환술 환자의 통증 및 균형 능력에 미치는 영향)

  • Jae-hong, Lee;Dong-ki, Min;Sang-jae, Lee
    • The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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    • v.28 no.3
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    • pp.79-87
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    • 2022
  • Background: The purpose of this study was to examine the effect of transcranial direct current stimulation (tDCS) on the pain and balance of patients who receive total knee arthroplasty (TKA). Methods: This study subjects were 24 patients in Hospital T, located in Daegu, South Korea who received TKA after being diagnosed with degenerative arthritis. The subjects were randomly divided into and experimental group and a control group, with each group including 12 patients. Both group received superfical thermal therapy, interferential current therapy (ICT), and continue passive motion (CPM), which are conventional knee therapy on the knee joint. The experimental group received the tDCS treatment three times a week for three weeks, from October 1st to October 20th. The visual analogue scale and Wii Balance Board system were used to measure the pain and balancing ability, respectively, of both groups. In the statistical result analysis, to compare about pre and post test difference in each groups was accomplished. Statistical analysis of independent t-test and paired t-test were conducted using SPSS version 23.0. Results: After three weeks of intervation, there were significantly difference in balance ability in pre and post test in the tDCS group. VAS decreased significantly in both groups(p<.05), There was a significantly difference in pain, balance ability in the tDCS group compared to the sham group. Conclusion: These results indicate that applying tDCS together with conventional knee joint therapy for TKA patients is effective in promoting the patients' recovery.

A Study on the Gold Foil Patch Design Using Traditional Patterns (전통문양을 활용한 금박패치디자인 연구)

  • Oh, Yu-Kyeong;Song, Jung-A
    • Fashion & Textile Research Journal
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    • v.24 no.1
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    • pp.95-107
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    • 2022
  • In reality, the distinction between the Korean traditional culture and the cultures of other countries is at a delicate boundary. Additionally in the wake of the recent socio-cultural confrontation between Korea and China, it has become necessary to establish the foundation and area of Korean traditional culture and to actively utilize the importance of improving awareness of Korean traditional culture. To reorganize the reckless use of the gold foil pattern shown in the rental hanbok, data on the museum's collection of gold leaf patterns were collected and analyzed. Based on the gold foil, Gilsang characters such as Phoenix pattern, Crane pattern, Bat pattern, Flower pattern, Fruit pattern and recovery advice were extracted through references. The traditional gold foil pattern was reconstructed and relocated to design the gold leaf patch. Based on the collection and analysis of the museum's relics, the Wonsam & Daedae, Dangeui, Sranchima, Sagyusam, Jeonbok, Bokgun, and Daenggi were produced. Therefore, we present the possibility of producing gold foil and modern methods for producing gold foil using laser cutting techniques that can express refinement and complexity well, and gold foil thermal transfer paper with retouchable effects. Additionally, we would like to reflect upon the practicality and the convenience to modern people by considering the complexity and hassle of the traditional gold foil production process, and the disadvantages of processes that require relatively longer time. It intends to help revitalize the market of Korean traditional clothing and fashion products.

Thermo-mechanical properties in bending of a multizone nickel-titanium archwire: A retrieval analysis

  • Panagiotis Roulias;Ioulia-Maria Mylonopoulou;Iosif Sifakakis;Christoph Bourauel;Theodore Eliades
    • The korean journal of orthodontics
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    • v.53 no.2
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    • pp.89-98
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    • 2023
  • Objective: This study aimed to compare the mechanical and thermal properties in the anterior and posterior segments of new and retrieved specimens of a commercially available multizone superelastic nickel-titanium (NiTi) archwire. Methods: The following groups of 0.016 × 0.022-inch Bioforce NiTi archwires were compared: a) anterior and b) posterior segments of new specimens and c) anterior and d) posterior segments of retrieved specimens. Six specimens were evaluated in each group, by three-point bending and bend and free recovery tests. Bending moduli (Eb) were calculated. Furthermore, the new specimens were evaluated with scanning electron microscopy/energy-dispersive X-ray spectrometry. A multiple linear regression model with a random intercept at the wire level was applied for data analysis. Results: The forces in the posterior segments or new specimens were higher than those recorded in the anterior segments or retrieved specimens, respectively. Accordingly, Eb also varied. Higher austenite start and austenite finish (Af) temperatures were recorded in the anterior segments. No statistically significant differences were found for these temperatures between retrieved and new wires. The mean elemental composition was (weight percentage): Ni, 52.6 ± 0.5; Ti, 47.4 ± 0.5. Conclusions: The existence of multiple force zones was confirmed in new and retrieved Bioforce archwires. The retrieved archwires demonstrated lower forces during the initial stages of deactivation in three-point bending tests, compared with new specimens. The Af temperature of these archwires may lie higher than the regular intraoral temperature. Even at 2 mm deflections, the forces recorded from these archwires may lie beyond biologically safe limits.

Suboptimal Mitochondrial Activity Facilitates Nuclear Heat Shock Responses for Proteostasis and Genome Stability

  • Dongkeun Park;Youngim Yu;Ji-hyung Kim;Jongbin Lee;Jongmin Park;Kido Hong;Jeong-Kon Seo;Chunghun Lim;Kyung-Tai Min
    • Molecules and Cells
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    • v.46 no.6
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    • pp.374-386
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    • 2023
  • Thermal stress induces dynamic changes in nuclear proteins and relevant physiology as a part of the heat shock response (HSR). However, how the nuclear HSR is fine-tuned for cellular homeostasis remains elusive. Here, we show that mitochondrial activity plays an important role in nuclear proteostasis and genome stability through two distinct HSR pathways. Mitochondrial ribosomal protein (MRP) depletion enhanced the nucleolar granule formation of HSP70 and ubiquitin during HSR while facilitating the recovery of damaged nuclear proteins and impaired nucleocytoplasmic transport. Treatment of the mitochondrial proton gradient uncoupler masked MRP-depletion effects, implicating oxidative phosphorylation in these nuclear HSRs. On the other hand, MRP depletion and a reactive oxygen species (ROS) scavenger non-additively decreased mitochondrial ROS generation during HSR, thereby protecting the nuclear genome from DNA damage. These results suggest that suboptimal mitochondrial activity sustains nuclear homeostasis under cellular stress, providing plausible evidence for optimal endosymbiotic evolution via mitochondria-to-nuclear communication.

Corrosion Behavior of Super Duplex Stainless Steel (STS 329J4L) Tubes and Fin-Tubes Used in Thermal Power Plant Applications (화력발전소용 슈퍼 듀플렉스 스테인리스 강(STS 329J4L) 조관 튜브 및 핀-튜브재의 부식거동)

  • Jin Sung Park;Yong Hyeon Kim;Seung Gab Hong;Sung Jin Kim
    • Corrosion Science and Technology
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    • v.22 no.6
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    • pp.435-446
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    • 2023
  • Corrosion behaviors of laser-welded super duplex stainless steel (SDSS) tubes after exposure to an actual power plant environment for one year and those of fin-tube welded SDSS were evaluated. Results showed that corrosion damage on the back side of the SDSS tube in the direction of hot air was higher than that on the front side regardless of weldment location. However, corrosion damage showed no difference between weldment and base metal due to recovery of phase fraction in the weldment through post weld heat treatment (PWHT). Nevertheless, the SDSS tube showed severe corrosion damage along grain boundary due to surface phase transformation (δ → γ) and Cr2N precipitation caused by PWHT with a high N2 atmosphere. Corrosion resistance of the SDSS tube was recovered when degraded surface was removed. Corrosion sensitivity of a fin-tube increased significantly due to pre-existing crevice, unbalanced phase fraction, and σ phase precipitation adjacent to the fusion line. Although corrosion resistance was improved by recovered phase fraction and sufficient dissolution of σ phase during PWHT, corrosion reaction was concentrated at the pre-existing crevice. These results suggest that welding conditions for fin-tube steel should be optimized to improve corrosion resistance by removing pre-existing crevice in the weldment.

Evaluation of the Basic Property Evaluation of Eco-powder, a Hydrothermal Synthesis Product for Improving Waste Vinyl Recycling Efficiency (농촌 폐비닐 활용률 제고를 위한 수열합성 생성물인 에코 파우더(Eco-powder)의 기초물성 평가)

  • Sun-Mi Choi;Min-Chul Lee;Jin-Man Kim;Young-Gon Son;Nam-Ho Kim
    • Resources Recycling
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    • v.33 no.1
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    • pp.48-57
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    • 2024
  • This study aimed to improve utilization of the Class C vinyl waste generated in rural areas based on a preliminary investigation on the use of eco-powder, generated through pyrolysis, as a raw material for plastic. The efficiency of pre-processing treatments in controlling ash content of the generated eco-powder and its effect on the basic properties of manufactured plastic were evaluated. The basic properties included ash content of the compressed eco-powder at different levels of ash content, impact strength, flexural strength, and tensile strength. The experimental results confirmed that pre-processing improved the separation efficiency of soil particles and vinyl waste through physical impact. The eco-powder with ash content of less than or equal to 26% was found to satisfy the target performance during impact strength, flexural strength, and tensile strength evaluation. Thus, it was confirmed that the Class C vinyl waste, having low utilization and recovery rates, could be effectively utilized as a plastic raw material after optimum thermal treatment and physical processing using the eco-powder.

Geometric Thermoelectric Generator Leg Shape Design for Efficient Waste Heat Recovery (효율적인 폐열 회수를 위한 기하학적 열전소자 다리 설계)

  • Hyeon-Woo Kang;Jung-Hoe Kim;Young-Ki Cho;Won-Seok Choi;Hyun-Ji Lee;Hun-Kee Kim
    • The Journal of the Korea institute of electronic communication sciences
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    • v.19 no.3
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    • pp.589-602
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    • 2024
  • Thermoelectric generator (TEG) generally do not have high heat conversion efficiencies. The performance of a thermoelectric generator module depends on the shape of the legs as well as the properties of the material and the number of legs. In this study, the leg shapes of thermoelectric elements are modeled into various geometric structures such as cylinder and cube shaped to efficiently harvest waste heat, and the electrical characteristics are compared numerically. The temperature gradient and power generation according to the bridge shape are found to be highest at the existing Cube shape. As a result of comparing the power generation using the cooling effect, the Cone shape was the highest in natural convection and the Hourglass shape was highest in forced convection. Research results confirm that geometry can affect the efficiency of thermoelectric generators.

Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2016 (설비공학 분야의 최근 연구 동향 : 2016년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.29 no.6
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    • pp.327-340
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    • 2017
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2016. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of flow, heat and mass transfer, the reduction of pollutant exhaust gas, cooling and heating, the renewable energy system and the flow around buildings. CFD schemes were used more for all research areas. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results of the long-term performance variation of the plate-type enthalpy exchange element made of paper, design optimization of an extruded-type cooling structure for reducing the weight of LED street lights, and hot plate welding of thermoplastic elastomer packing. In the area of pool boiling and condensing, the heat transfer characteristics of a finned-tube heat exchanger in a PCM (phase change material) thermal energy storage system, influence of flow boiling heat transfer on fouling phenomenon in nanofluids, and PCM at the simultaneous charging and discharging condition were studied. In the area of industrial heat exchangers, one-dimensional flow network model and porous-media model, and R245fa in a plate-shell heat exchanger were studied. (3) Various studies were published in the categories of refrigeration cycle, alternative refrigeration/energy system, system control. In the refrigeration cycle category, subjects include mobile cold storage heat exchanger, compressor reliability, indirect refrigeration system with $CO_2$ as secondary fluid, heat pump for fuel-cell vehicle, heat recovery from hybrid drier and heat exchangers with two-port and flat tubes. In the alternative refrigeration/energy system category, subjects include membrane module for dehumidification refrigeration, desiccant-assisted low-temperature drying, regenerative evaporative cooler and ejector-assisted multi-stage evaporation. In the system control category, subjects include multi-refrigeration system control, emergency cooling of data center and variable-speed compressor control. (4) In building mechanical system research fields, fifteenth studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, renewable energies, etc. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which could be help for improving the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the analyses of indoor thermal environments controlled by portable cooler, the effects of outdoor wind pressure in airflow at high-rise buildings, window air tightness related to the filling piece shapes, stack effect in core type's office building and the development of a movable drawer-type light shelf with adjustable depth of the reflector. The subjects of building energy were worked on the energy consumption analysis in office building, the prediction of exit air temperature of horizontal geothermal heat exchanger, LS-SVM based modeling of hot water supply load for district heating system, the energy saving effect of ERV system using night purge control method and the effect of strengthened insulation level to the building heating and cooling load.