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        검색결과 1,410

        181.
        2021.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The nutrient balances originated from livestock manure in Korea has not being include minor livestock species (e.g., horse, deer, and goat) since their manure excretion unit (MEU), nutrient excretion unit (NEU), and nutrient loading coefficient (NLC) are not known yet. In the present research work, the primary focus had laid therefore on securing domestic MEU for the specified minor livestock species which provides the basis for the computation of NEU and NLC. Moreover, the nutrient potential and economic value of composted manure from minor livestock was assessed on the basis of contents in the inorganic fertilizers such as Urea, (46% N) and Fused superphosphate (20% phosphorus pentoxide). The obtained MEU was found to be 10.52±5.48, 4.07±1.69, and 0.843±0.1 kg/head/day for horse, deer, and goat, respectively. In addition, the measured NLCs of horse, deer, and goat were [N, 0.7; P, 0.9], [N, 0.7; P, 0.6] (Both deer and goat were the same.), respectively. Consequently, the horse, deer, and goat manure have a potential of 3,840.1 ton N/year and 9,390.2 ton P/year as an inorganic fertilizer of urea and fused superphosphate. These findings may facilitate the development of more accurate nutrient budget taking into account both major and minor livestock and improve the manure management measures for land application.
        4,500원
        182.
        2021.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In a region fraught with tensions and conflicts, the South China Sea Arbitral Award Case (Case) concerned maritime conflicts between the Philippines and China, an inter-State, non-consensual, ex-parte arbitration under Annex VII of the UN Law of the Sea Convention (UNCLOS). The Case went against China. The Annex VII Tribunal decision of first and last instance, was final and without appeal. However, to the authors, the Case drew attention to the inherently unfair provisions of an exparte hearing under Annex VII that violates the principle of natural justice and casts uncertainty on the role and future of mandatory conciliation under the UNCLOS. These omissions are addressed here. Noting these omissions and limitations, to restore regional goodwill, ameliorate conflicts and tensions, and promote dispute settlement, a solution in mandatory conciliation is proposed -“A Partnership in Comity and Conciliation for the South China Sea”- with its provenance rooted in international law.
        6,400원
        195.
        2021.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This research aims to study the effect of impregnation ratio and activation temperature on microporous development of activated carbon (AC). Rubberwood chips, which are wasted from home furnishing industry, were used as precursors for synthesized of activated carbon by chemical activation employing Potassium hydroxide (KOH) as activation agent. Rubberwood char was carbonized at 400 °C for 1 h under inert gas. In this experiment, the rubberwood chars were impregnated with KOH solution by 1:1–3 (char: KOH) impregnation ratio for 24 h, then the samples were activation at 600–800 °C. Surface area, pore volume, micropore volume, pore size distribution, adsorption isotherm and porous structure were analyzed in this experiment to identify the properties of derived activated carbon. According to the investigation, the activated carbon, activated at 800 °C with impregnation ratio of 1:3, demonstrated the highest surface area, pore volume and micropore volume as 1491.75 m2/g, 0.6777 cm3/g, and 0.5813 cm3/g, respectively. Its average pore size was 1.82 nm and it also showed type I adsorption isotherm which indicates as microporous solid.
        4,000원
        196.
        2021.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Activated non-graphitizable hard carbon using orange peel with mesoporous structure has been prepared by pyrolyzation at 700, 800, 900 °C using chemical activation method. The activated orange peel-derived hard carbon has been characterized for its mesoporous and disordered structure. TG-DSC gives the information for the changes about sample composition and thermal stability of the materials. Increasing the carbonization temperature for orange peel precursor using NaOH as activating agent, elevates the pore diameter, which thereby facilitating the insertion of Na+. Raman and X-ray diffraction confirms the presence of disordered carbon. The surface morphology of the material was analyzed by scanning eletron microsope and nitrogen ( N2) adsorption and desorption analysis give the morphology, mesopore size (3.374, 3.39 and 4 nm) and surace area (60.164, 58.99 and 54.327 m2/g) of the orange peel-derived hard carbon. Hence, this work strongly evidences that the biomass-derived hard carbon with good porosity and paves way of superior electrochemical performance for emerging sodium ion batteries.
        4,000원
        197.
        2021.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The paper deals with a comparative study of equilibrium and kinetics of phenol adsorption from aqueous solutions by means of commercial activated carbons and semi-cokes, differing in the nature of feedstock, production technology and structural characteristics. The main adsorption parameters are calculated with the usage of Langmuir and Dubinin–Radushkevich equations. The change in the characteristics of the structure and state of the surface of semi-coke P2 as a result of modification is estimated. It was found that phenol adsorption kinetics is described by a pseudo-second-order model. The adsorption rate constants and the coefficient of external diffusion mass transfer are calculated. It is proved that phenol extraction from aqueous solutions presents a mixed-diffusion nature, and the process rate is limited by external mass transfer for 13 min for SKD-515 and 22 min for ABG. To increase the adsorption capacity, the oxidative modification of the semi-coke P2 was carried out. Considering the economic and technological aspects, ABG semi-coke is recognized as a promising sorbent for phenol extraction from aqueous media.
        4,000원
        198.
        2021.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The high level of lithium storage in synthetic porous carbons has necessitated the development of accurate models for estimating the specific capacity of carbon-based lithium-ion battery (LIB) anodes. To date, various models have been developed to estimate the storage capacity of lithium in carbonaceous materials. However, these models are complex and do not take into account the effect of porosity in their estimations. In this paper, a novel model is proposed to predict the specific capacity of porous carbon LIB anodes. For this purpose, a new factor is introduced, which is called normalized surface area. Considering this factor, the contribution of surface lithium storage can be added to the lithium stored in the bulk to have a better prediction. The novel model proposed in this study is able to estimate the lithium storage capacity of LIB anodes based on the porosity of porous carbons for the first time. Benefiting porosity value (specific surface area) makes the predictions quick, facile, and sensible for the scientists and experts designing LIBs using porous carbon anodes. The predicted capacities were compared with that of the literature reported by experimental works. The remarkable consistency of the measured and predicted capacities of the LIB anodes also confirms the validity of the approach and its reliability for further predictions.
        4,000원
        199.
        2021.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Double-layer graphene nanoribbons promise potential application in nanoelectromechanical systems and optoelectronic devices, and knowledge about mechanical stability is a crucial parameter to flourish the application of these materials at the next generation of nanodevices. In this paper, molecular mechanics is utilized to investigate nonlinear buckling behavior, critical buckling stress, and lateral deflection of double-layered graphene nanoribbons under various configurations of stacking mode and chirality. The implicit arc-length iterative method (modified Riks method) with Ramm’s algorithm is utilized to analyze the nonlinear structural stability problem. The covalent bonds are modeled using three-dimensional beam elements in which elastic moduli are calculated based on molecular structural mechanics technique, and the interlayer van der Waals (vdW) interactions are modeled with nonlinear truss elements. An analytical expression for Young’s modulus of nonlinear truss elements is derived based on the Lennard–Jones potential function and implemented in numerical simulation with a UMAT subroutine based on FORTRAN code to capture the nonlinearity of the vdW interactions during the buckling analysis. The results indicate that the highest critical buckling stress and the minimum lateral deflection occur for armchair and zigzag chirality, both with AB stacking mode, respectively. Moreover, the critical buckling stress is found to be directly dependent on the mode shape number regardless of in-phase or anti-phase deflection direction of layers. Lateral deflection exhibits a similar trend with mode shape in anti-phase mode; however, it is decreasing by increasing mode shape number in in-phase mode.
        4,900원
        200.
        2021.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, Fe3O4/ MgO/Activated carbon composite was used to remove arsenic ion (As (III)) from aqueous media. To this end, Frangula Alnus was used to prepare activated carbon (AC) by calcination in the furnace at 700 °C for 4 h and was then used to synthesize the MgO/Fe3O4/AC composite. To study the surface properties of the composite, various analyses such as SEM, EDX/Mapping, FTIR, DLS, BET and VSM were applied. According to the BET analysis, the specific surface area and average pore size of the Fe3O4/ MgO/AC composite were obtained as 190.92 m2/g and 7.57 nm, respectively, which showed that the aforementioned nanocomposite had a mesoporos structure with an excellent specific surface area. Also, VSM analysis indicated that the composite had a superparamagnetic property and could be easily separated from the solution by a magnet. Moreover, the results of the As (III) sorption indicated that the highest uptake efficiency was obtained 96.65% at pH = 7, adsorbent dosage = 0.13 g/L, t = 35 min, T = 45 °C and Co = 6 mg/L. In addition, the pseudo-second-order model could better describe the kinetic behavior of the sorption process. Furthermore, Langmuir model was the best model to describe the equilibroium behavior of the As(III) ion sorption. Besides, according to the the thermodynamic study, enthalpy change and entropy change were obtained 58.11 kJ/mol and 224.49 J/mol.K, respectively, indicating that the sorption process was spontaneous and endothermic. According to the results, the Fe3O4/ MgO/AC composite was a good adsorbent with the extraordinary properties, which can be used on an industrial scale.
        4,300원