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        검색결과 17

        2.
        2022.01 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Breakthrough analysis has widely been explored for the dynamic separation of gaseous mixtures in porous materials. In general, breakthrough experiments measure the components of a flowing gas when a gaseous mixture is injected into a column filled with an adsorbent material. In this paper, we report on the design and fabrication of a breakthrough curve measurement device to study the dynamic adsorptive separation of hydrogen isotopologues in porous materials. Using the designed system, an experiment was conducted involving a 1:1 mixture of hydrogen and deuterium passed through a column filled with zeolite 13X (1 g). At room temperature, both hydrogen and deuterium were adsorbed in negligible amounts; however, at a temperature of 77 K, deuterium was preferentially adsorbed over hydrogen. The selectivity was different from that in the existing literature due to the different sample shapes, measurement methods, and column structures, but was at a similar level to that of cryogenic distillation (1.5).
        4,000원
        3.
        2021.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Global warming and climate changes are the ultimate consequences of increased CO2 volume in the air. Physical activation was used to prepare high-throughput activated carbon from a low-cost date stone. The adsorption performance of activated carbon using fixed bed for CO2 separation was studied. The reliance of temperature, flow rate, and initial CO2 concentration levels on breakthrough behaviour was analysed. The adsorption response was explored in terms of breakthrough and saturation points, adsorption capacity, temperature profiles, utilization factor, and length of mass-transfer zone. Increased temperatures lead to vary the breakthrough periods notably. The vastly steep breakthrough curves reveal satisfactory utilization of bed capacity. LMTZ is varied positively with increased feed rates and temperatures. The high utilization factor of 0.9738 with 1.66 mmol/g CO2 uptake was acquired at 298 K and 0.25 bars. The findings recommend that the carbon prepared from date stone is encouraging to capture CO2 from CO2/ N2 mixture.
        4,300원
        4.
        2021.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        전자 및 화학 산업의 초순수 생산 및 원자력 발전소의 부식 제어를 위해 이온교환 수지탑의 성능 파악이 필수적이다. 따라서 본 연구에서는 4종의 H 및 ETAH 형 양이온 교환수지가 채워진 양이온 및 혼상 이온교환수지탑에 미량의 NaCl를 포함하는 에탄올아민(ETA) 및 암모니아(NH3) 용액을 주입하여 양이온 파과특성을 조사하였다. 조사 결과, 주성분인 ETAH+ 및 NH4 +와 달리, 미량성분인 Na+는 (이론적교환용량의 3배 이상) 시험기간 동안 수지탑 출구에서 파과 및 오버슈팅 현상이 나타나지 않았다. H형 수지탑의 파과현상은 ETAH+ 및 NH4 +가 순서대로 일어났고, 오버슈팅은 NH4 +가 파과할때 ETAH+에 대해서 발생했다. 파과영역의 너비로 결정되는 상대적 선택도는 NH4 +가 ETAH+보다 최대 51.5 % 더 높았다. 유입수 Na+ 농도가 높을수록, 선택도는 감소하고 오버슈팅 현상은 증가하였다. 이온교환 수지의 고유 특성을 개선하여 감소시킬 수 있는 Na+ 누출은, ETAH형에서 높았고 4종의 양이온수지에 대해 동일하지 않은 것으로 조사되었다.
        4,300원
        5.
        2021.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The 1980s is the golden decade for the vigorous development of Chinese films. During this period, the documentary aesthetics led by the fourth generation of directors quietly rose. Under the background of great changes in China's politics, economy and culture, Chinese films, which inherit the original production system and decades of development experience, are full of vitality. On the one hand, they are accusing history, on the other hand, they are seeking a kind of seclusion and evasion, and they are digesting their youth sacrifice in the "real" image. Taking old stories in the south of the city as an example, this paper re examines the works of the fourth generation directors from the aspects of narrative motivation and complex mood expression, in order to provide new ideas and perspectives for how to express Chinese stories and Chinese culture in the era of cultural globalization. We should actively sum up and absorb the achievements of Chinese films in the 1980s. In the current context of cultural globalization, we should use practice to seek and explore how to use Chinese image language to tell Chinese stories and express profound, beautiful and profound Chinese culture.
        4,600원
        6.
        2018.07 구독 인증기관 무료, 개인회원 유료
        Introduction Many extant studies in the strategic management literature show that a firm’s network influences its innovation outcomes (Ahuja, Lampert, & Tandon, 2008). Networks are characterized by strong and weak ties in terms of the combination of the amount of time, intensity, intimacy, and reciprocal services (Granovetter, 1973). There is, however, a continuing debate about the relative advantages of strong and weak ties. These equivocal findings suggest that the relationship between tie strength and a firm’s innovation outcome is complex, and call for a more detailed examination of this relationship. The implications of networks for a firm’s innovation outcomes are quite significant. Nevertheless, the majority of research studies still examine networks using simple dyadic relationships (e.g., Capaldo, 2007). In reality, a firm’s networks are composed of more than a single dyadic relationship and are much more complex. Thus, dyadic approaches are limited in providing understanding of networks on a firm’s innovation performance. As such, we will take the perspective of a focal firm in a triad network. While still relatively simple, the triad network approach allows us to identify key relationships previously unexplored in network tie configuration, and to shed light on the equivocal results in the extant literature. Specifically, we will examine the position of the strong or weak ties among the firms, and also whether the strong or weak ties are adjacent or non-adjacent to the focal firm. Breakthrough innovation is defined as the basic invention, which leads to the evolution of many subsequent technological developments (Ahuja & Lambert, 2001). This definition suggests that novel and unique knowledge is required to create breakthrough innovation. Indeed, recent research shows that firms need novel knowledge created by network partners to create breakthrough innovation (e.g., Srivastava & Gnyawali, 2011). As such, we investigate how different levels of novel and diverse knowledge arising from the position of network ties impact a focal firm’s breakthrough innovation. Nevertheless, obtaining diverse and novel knowledge from networks does not guarantee the creation of successful breakthrough innovation. A firm needs a capability to learn, absorb and integrate the new knowledge into its works, which is its absorptive capacity. Thus, we examine the moderating role of a firm’s absorptive capacity on the relationship between the impact of the configurations arising from the position of strong/weak ties and a firm’s breakthrough innovation in a triad network relationship. Conceptual Framework We posit six different types of network configurations based on tie strength and position of strong/weak ties that are adjacent or non-adjacent to the focal firm in a triad (Figure 1). For example, Configuration 1 has three strong ties and Configuration 6 has three weak ties. Configuration 2 has two strong ties that are adjacent to a focal firm and one weak tie that is non-adjacent to a focal firm in a triad. Importantly, we use two theories (i.e., network theor and relational theory) to elaborate the impact of six configurations on a firm’s breakthrough innovation, considering the tie strength, the position of strong/weak ties, and whether the strong or weak ties are adjacent or non-adjacent to the focal firm. The first of these is network theory. Network theory and relational theory assert different effects of strong versus weak ties on a firm’s breakthrough innovation. To resolve the ambiguities in the literature on this issue, we combine network theory and relational theory and investigate the implication of the position of the strong or weak ties. We argue that the position of strong/weak ties must be considered to explain the impact of tie strength on firm breakthrough innovation in a triad context. For example, Configuration 2 has two strong ties adjacent to focal firm and one weak tie non-adjacent to focal firm (Figure 1). The non-adjacent weak tie provides potential for diverse and novel knowledge and reduced knowledge redundancy. Also, adjacent two strong ties provide the benefits of commitment and trust, and rich information flow. Additionally, these adjacent strong ties facilitate the transfer of novel knowledge generated from the non-adjacent weak tie. Thus, we argue that Configuration 2 has a potentially positive influence on firm breakthrough innovation. Configuration 5 has two adjacent weak ties and one non-adjacent strong tie. The non-adjacent strong tie has high knowledge redundancy and high trust and commitment between the two actors B and C (Figure 1). The non-adjacent strong tie between B and C induces potential opportunistic tendencies toward focal firm and inhibits information sharing with the focal firm. This indicates that the two firms form an alliance to the detriment of the focal firm. Further, adjacent weak ties provide novel and diverse information while maintaining less commitment and trust with the focal firm. Importantly, diverse information from adjacent weak ties is degraded because of the knowledge redundancy generated by non-adjacent strong tie between B and C. Thus, we argue that Configuration 5 has potentially negative influence on firm breakthrough innovation. The above discussion suggests that one cannot determine which type of network ties will tend create a firm’s breakthrough innovation simply by counting the numbers of weak and strong ties in the configurations. One must also consider the position of the strong and weak ties within the network and the focal firm’s absorptive capacity. For example, though there is a high level of knowledge redundancy created by the non-adjacent strong tie in Configuration 5, if the focal firm has strong ability to learn, the focal firm can still capture and use the limited new knowledge, depending on its absorptive capacity. Next, we explain how firm’s absorptive capacity influences the relationship between six configurations and breakthrough innovation. Methods We will collect a full sample of data from three main data sources: alliance data from the Securities Data Company (SDC) on Joint and Alliances, patent data from the National Bureau of Economic Research (NBER) U.S. Patent Citation 1997-2016, and financial data from COMPUSTAT. The initial sample will consist of all firms that announced a triad of strategic alliance firms across industries from 1997 to 2016 in the United States. Implications Our study makes two key contributions. First, we investigate the impact of various triad strong/weak tie network configurations on a firm’s breakthrough innovation. We test various effects accrued from the position of strong/weak ties that are adjacent or non-adjacent to a focal firm on the focal firm’s breakthrough innovation in the triad network. By examining these relationships, we uncover critical implications of the tie strength previously unexplored in the network literature. We provide conceptual advancement of Granovetter’s notion of the strength of weak ties, showing the importance of the position of strong or weak ties as a critical driver to influence a firm’s breakthrough innovation. Second, we investigate how a focal firm’s absorptive capacity moderates the impact of network configurations on a firm’s breakthrough innovation. This provides a more precise and fine-grained understanding of how a firm’s capability to absorb outside knowledge influences the relationship between network configurations and a focal firm’s breakthrough innovation. Combined, our two contributions help to resolve some of the equivocal results in the extant literature regarding the effects of strong or weak ties on breakthrough innovation.
        3,000원
        8.
        2015.01 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The breakthrough behaviour of activated charcoal cloth samples against an oxygen analogue (OA) of sulphur mustard has been studied using the modified Wheeler equation. Activated charcoal cloth samples having different surface area values in the range of 481 to 1290 m2/g were used for this purpose. Breakthrough behaviour was found to depend on the properties of the activated charcoal cloth, properties of the OA and the adsorption conditions. Activated charcoal cloth with a high surface area of 1290 m2/g, relatively large surface density of 160 g/m2 and coarser fiber structure exhibited better kinetic saturation capacity value, 0.19 g/g, against OA vapours when compared to others, thus confirming its potential use in foldable masks for protection against chemical warfare agents.
        4,000원
        9.
        2014.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        다니엘 올브라트는 문학을 연구하고 가르친 시간이 아주 길다. 그는 많은 글을 썼고, 그가 쓴 모든 책들은 독창적이고, 많은 후학과 학자들의 귀감이 되고있다. 그의 최근의 관심을 이렇게 표현 한다: “예술작품이 절대적이라 여겨지고 그 텍스트가 모든 맥락과 절단되면, 그것은 한 무더기의 모기떼로 흩어지게 될 것이다. 예술작품이 그 작품의 고유의 문화의 대표적 표현으로 여기지면, 그 작품은 갑옷을 입은, 공처럼 둥글게 변하는 아마딜로가 될 것이다” (233). 이제 우리는 텍스트에서 눈을 떼서 우리 주변의 것들에 돌려야 할 때이다. 이런 말에도 불구하고, 올브라트는 텍스트 자체도 깊이 파고들었다.
        4,300원
        10.
        2012.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A nuclear, biological, chemical (NBC) canister was indigenously developed using active carbon impregnated with ammoniacal salts of copper (II), chromium (VI) and silver (I), and high efficiency particulate aerosol filter media. The NBC canister was evaluated against carbon tetra chloride (CCl4) vapours, which were used as a simulant for persistent chemical warfare agents under dynamic conditions for testing breakthrough times of canisters of gas masks in the National Approval Test of Respirators. The effects of CCl4 concentration, test flow rate, temperature, and relative humidity (RH) on the breakthrough time of the NBC canister against CCl4 vapour were also studied. The impregnated carbon that filled the NBC canister was characterized for surface area and pore volume by N2 adsorption-desorption isotherm at liquid nitrogen temperature. The study clearly indicated that the NBC canister provides adequate protection against CCl4 vapours. The breakthrough time decreased with the increase of the CCl4 concentration and flow rate. The variation in temperature and RH did not significantly affect the breakthrough behaviour of the NBC canister at high vapour concentration of CCl4, whereas the breakthrough time of the NBC canister was reduced by an increase of RH at low CCl4 vapour concentration.
        4,000원
        11.
        2010.09 KCI 등재후보 구독 인증기관 무료, 개인회원 유료
        In this study, the QA/QC test for the combined application of DNPH cartridge – HPLC/UV method was investigated in the collection and analysis of formaldehyde in air using three types of DNPH cartridge samplers made by three independent manufacturers. For these experiments, gaseous standards of formaldehyde (FA) were prepared at 7 concentration levels that fell in the range of 44.1~3400 nmol/mol. According to our analysis, the levels of cartridge blank (0.13 ~ 0.26 ng) are found to be fairly high to require routine check up for each experiment. The recovery patterns of FA were highly comparable between different cartridge products, when standard gases are supplied in the concentration range up to 177 nmol/mol. All 3 types of DNPH cartridge exhibited highly similar recovery rates at concentrations below 1.7 ㎛ol/mol, while the maximum recovery was attained from the product B. The overall results of our study suggest that one should calibrate the samples in the optimal range of recovery with routine check up of blank values.
        4,300원
        12.
        2006.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        다공성 폴리비닐리덴플루오라이드(PVDF, polyvinylidenefluoride) 그리고 폴리테트라플루오르에틸렌(PTFE, Polytetrafluoroethylene)에 대하여 순수한 물, 0.1 M~4.0 M NaOH 수용액, 그리고 0.1 M~3.0 M NaHSO3 수용액을 사용하여 임계투과압력을 측정하였다. 임계투과압력은 동일한 평균 기공 크기의 PVDF보다 PTFE가 크게 나타남을 관찰할 수 있었다. NaOH 수용액의 경우 NaOH의 농도 증가에 따라 임계투과압력은 감소하였으며 1.0 M 농도에서 최소값을 나타낸 후 다시 증가함을 확인하였다. 그러나 NaOH이 아닌 다른 염을 용해한 수용액인 NaHSO3 수용액의 경우 농도를 3.0 M까지 증가하여도 임계투과압력이 계속 감소함을 알 수 있었다. 이와 같은 현상을 이론적인 Cantor식으로 해석할 수 있었다.
        4,000원
        13.
        2000.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The VOCs(Volatile Organic Compounds) is one of the major cause for the atmosphere pollution. Breakthrough behavior of benzene and toluene in adsorption bed packed with activated carbon was experimentally studied. Composition and temperature of the gas flowing in the bed was measured and breakthrough curves for each component was obtained. Breakthrough time of benzene was earlier than that of toluene due to relatively weak adsorptivity. The relationship between breakthrough time and flow rate was obtained. The shape of temperature change with time was dependent on the position in the bed. Temperature changed faster and sharper in the inlet than in the outlet. It was noted that breakthrough behavior could be affected by the heat transfer properties.
        4,000원
        14.
        2022.10 KCI 등재 서비스 종료(열람 제한)
        A zeolite material with a Si/Al molar ratio of 1.2 was synthesized by changing the NaOH/CFA ratio of coal fly ash (CFA) via a fusion/hydrothermal reaction in the HD thermal power plant. The change in the crystal structure of the zeolite was confirmed using XRD and SEM, and the ammonia adsorption capacities of the synthesized zeolitic materials and a commercial zeolite (Na-A zeolite) were analyzed via an ammonia temperature-programmed desorption (NH3-TPD) process. The SEM and XRD results revealed out the zeolitic materials from the coal fly ash maintained a hexagonal Linde-type crystal structure similar to that of Na-A zeolite, but the crystallinity of the synthesized zeolitic material was reduced due to impurities. The NH3 adsorption capacity, determined from the NH3-TPD analysis of was 1.122 mmol/g of the synthesized zeolitic material, which was lower than the NH3 adsorption capacity of the Na-A zeolite.
        15.
        2016.04 서비스 종료(열람 제한)
        It is important to doubt common knowledge established in the past when we face difficulty to seek further development based on them. In this presentation the importance of doubting common knowledge is pointed out for further endless development of the field of study by discussing stagnation of chloride ion ingress and liquid water penetration into concrete, stagnation of water pass through a crack in concrete and the inconsistency between Carbonation depth and cover concrete spalling risk.
        16.
        2014.06 KCI 등재 서비스 종료(열람 제한)
        The adsorption experiments of lithium ions were conducted in the fixed bed column packed with activated carbon modified with nitric acid. Effect of inlet concentration, bed hight and flow rate on the removal of lithium ions was investigated. The experimental results showed that the removal and the adsorption capacity of lithium ions increased with increasing inlet concentration, and decreased with increasing flow rate. When the bed height increased, the removal and the adsorption capacity increased. The breakthrough curves gave a good fit to Bohart-Adams model. Adsorption capacity and breakthrough time calculated from Bohart-Adams model, these results were remarkably consistent with the experimental values. The adsorption capacity was not changed in the case of 3 times repetitive use of adsorbent.
        17.
        2014.01 KCI 등재 서비스 종료(열람 제한)
        Adsorption of phenol on activated carbon in a fixed bed was studied. The effects of fixed-bed length, superficial velocity (flow rate) and particle size of adsorbent on fixed-bed performance were investigated. Some characteristic parameters such as the breakthrough time (t0.05), saturation time (t0.95), length of mass transfer zone (LMTZ), adsorptive capacity (W), and adsorption rate constant (Ka) were derived from the breakthrough curves. Adsorbent particle sizes significantly affected the shape of the breakthrough curve. Larger particle sizes resulted in an earlier breakthrough, a longer LMTZ and a lower adsorption rate. Superficial velocity was a critical factor for the external mass transfer during fixed-bed adsorption process. The external mass transfer resistance was dominant as increasing superficial velocity.