• Safety and Health at Work
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• v.15 no.1
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• pp.87-95
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• 2024

Background: This study focuses on assessing occupational risk for the health hazards encountered during maintenance works (MW) in semiconductor fabrication (FAB) facilities. Objectives: The objectives of this study include: 1) identifying the primary health hazards during MW in semiconductor FAB facilities; 2) reviewing the methods used in evaluating the likelihood and severity of health hazards through occupational health risk assessment (OHRA); and 3) suggesting variables for the categorization of likelihood of exposures to health hazards and the severity of health effects associated with MW in FAB facilities. Methods: A literature review was undertaken on OHRA methodology and health hazards resulting from MW in FAB facilities. Based on this review, approaches for categorizing the exposure to health hazards and the severity of health effects related to MW were recommended. Results: Maintenance workers in FAB facilities face exposure to hazards such as debris, machinery entanglement, and airborne particles laden with various chemical components. The level of engineering and administrative control measures is suggested to assess the likelihood of simultaneous chemical and dust exposure. Qualitative key factors for mixed exposure estimation during MW include the presence of safe operational protocols, the use of air-jet machines, the presence and effectiveness of local exhaust ventilation system, chamber post-purge and cooling, and proper respirator use. Using the risk (R) and hazard (H) codes of the Globally Harmonized System alongside carcinogenic, mutagenic, or reprotoxic classifications aid in categorizing health effect severity for OHRA. Conclusion: Further research is needed to apply our proposed variables in OHRA for MW in FAB facilities and subsequently validate the findings.

• Journal of the Daesoon Academy of Sciences
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• v.28
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• pp.103-131
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• 2017

As the establishment of self-identity is based on 'Relationships of Mutual Beneficence,' the formation of 'Relationships of Mutual Beneficence' is the only road to the security and confirmation of self-existence. But given that our ordinary life almost entirely consists of actions objectifying others, the formation of 'Relationships of Mutual Beneficence' is by no means easy. The formation of 'Relationships of Mutual Beneficence' should be based on morality, controlling self-desire, and not objectifying others. Philosophy based on a priori reasoning describes self-control over selfdesire as the domination of the body through a priori reasoning. But this practical philosophy cannot present a self-evidential internal motivation behind moral actions. Due to this, the application of moral order given by a priori reasoning in response to reality is likely to be reinterpreted on basis of self-interest. With regards to this, the 'propensity towards sympathy' is given as new moral norm. The 'propensity towards sympathy' as emotion is direct and consistent given that feeling occurs prior to thinking. The 'propensity towards sympathy' is intuitive in the sense that it is an instinctual response preceeding a reasoned judgment. The 'propensity towards sympathy,' as a natural moral emotion, is self-validating given that all human beings know it and practice it. But previous studies on the 'propensity towards sympathy' have an obvious limitation because they adopt phenomenological approaches to the 'propensity towards sympathy' which eschew the investigation of morality. Though they present the 'propensity towards sympathy' as a natural emotion based on body rather than reason, they do not philosophically explain the 'propensity towards sympathy.' Thus the 'propensity towards sympathy' as a natural moral emotion is likely to be interpreted as a subjective and relative moral norm. This paper philosophically explains that the 'propensity towards sympathy' is a universal moral norm on the basis of Merleau-Ponty's 'flesh.' 'Flesh' is formed as the entanglement between oneself and others and presents the 'propensity towards sympathy' as its philosophical basis. In other words, 'flesh' formed as the mixture or entanglement between oneself and others is the material foundation upon which one can activate the 'propensity towards sympathy.' This paper's approach to the 'propensity of sympathy' can be desribed as a phenomenological approach to the 'propensity towards sympathy' as a universal moral norm.

• Bulletin of the Korean Chemical Society
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• v.24 no.6
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• pp.864-880
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• 2003

A unified picture for magnetism, superconductivity, quantum optics and other properties of molecule-based materials has been presented on the basis of effective model Hamiltonians, where necessary parameter values have been determined by the first principle calculations of cluster models and/or band models. These properties of the matetials are qualitatively discussed on the basis of the spin and pseudo-spin Hamiltonian models, where several quantum operators are expressed by spin variables under the two level approximation. As an example, ab initio broken-symmetry DFT calculations are performed for cyclic magnetic ring constructed of 34 hydrogen atoms in order to obtain effective exchange integrals in the spin Hamiltonian model. The natural orbital analysis of the DFT solution was performed to obtain symmetry-adapted molecular orbitals and their occupation numbers. Several chemical indices such as information entropy and unpaired electron density were calculated on the basis of the occupation numbers to elucidate the spin and pair correlations, and bonding characteristic (kinetic correlation) of this mesoscopic magnetic ring. Both classical and quantum effects for spin alignments and singlet spin-pair formations are discussed on the basis of the true spin Hamiltonian model in detail. Quantum effects are also discussed in the case of superconductivity, atom optics and quantum optics based on the pseudo spin Hamiltonian models. The coherent and squeezed states of spins, atoms and quantum field are discussed to obtain a unified picture for correlation, coherence and decoherence in future materials. Implications of theoretical results are examined in relation to recent experiments on molecule-based materials and molecular design of future molecular soft materials in the intersection area between molecular and biomolecular materials.

• Elastomers and Composites
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• v.49 no.1
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• pp.43-52
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• 2014

The effect of nanoclay (Cloisite 20A) on the self-adhesion behavior of uncured brominated-isobutylene-isoprene rubber (BIIR) has been studied. The dispersion state of nanoclay into the rubber matrix was examined by SEM, TEM and XRD analysis. The thermal degradation behavior of the filled and unfilled samples was examined by TGA and improvement in the thermal stability of the nanocomposites occurred based on the weight loss (%) measurements. Also, addition of nanoclay enhanced the cohesive strength of the material by reinforcement action thereby reducing the degree of molecular diffusion across the interface of butyl rubber. However, the average depth of penetration of the inter-diffused chains was still adequate to form entanglement on either side of the interface, and thus offered greater resistance to peeling, resulting in high tack strength measurements. The improvement in tack strength was only achieved at critical nanoclay loading above 8 phr. Contact angle measurement was also made to examine the surface characteristics. There was no significant interfacial property change by employing the nanoclay.

• Journal of the Korea Concrete Institute
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• v.24 no.5
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• pp.509-516
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• 2012

The aims of this research is to develop a fire resistant admixture to enhance high-pressured pumping of high-strength concrete (HSC) with a compressive strength of 60~80 MPa. Generally, the efficiency of HSC high-pressured pumping is dramatically reduced due to entanglement of short fibers added to prevent fire spalling. Therefore, the fire resistant admixture that can facilitate pumping of fire resistant HSC is urgently needed presently. The fire resistant HSC mix is comprised of Polypropylene fiber, Nylon fiber and Polymer powder. The test results showed that the slump-flow was improved by approximately 70% of the HSC without fire resistant admixture. However, the air void content was increased slightly due to the addition. The standard design compressive strength at 28-days was satisfied, while its flexural strength was similar to the concrete without the admixture. Since the flexural strength was 12~15% of its compressive strength, the general trend of flexural to compressive strength ratio in normal concrete was maintained. Even though its elastic modulus was decreased by adding the admixture, the study results showed that the concrete can be used for construction since all of the test results exceeded the code requirements.

• Cartoon and Animation Studies
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• s.41
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• pp.429-454
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• 2015

The starting point of this discussion resides in the 'eyes' of mirror in a sense of seeing the self reflected in a mirror. The meaning of mirror has been evolved over the centuries while strengthening its sense of identity by bringing up some questions for resemblance, reproduction, self-reflection and reality. A mirror has also extended its vision and provided with a range of images that the self can't have. In this regard, looking into a mirror has been a sustained focus of attention by creating another ostensible being of self-image. This shows the two sides of mirror, which reveals an ambiguous gap between substance and illusion. An excessive immersion in a reflected image in a mirror is intensified and expressed today. The eyes of mirror consisting of a complex dual structure show relations between a person who sees and a person who is seen, which draws a hazy line of demarcation between the subject and the object. This opens up the possibility of the world of chiasme, where you could face all the aspects being from the eyes of others. Furthermore, the meaning of the reflection in a mirror has formed a creative discourse as an enigmatic medium that creates a variety of 'eyes' in various forms of aesthetic expression like paintings and literature. I accordingly suggest that the 'eyes of mirror' is the ambiguous 'eyes of human being' reflected in two territories of the world. Therefore, I will present the historical development of the perspective on the mirror to take a concrete approach in which it opens up the reflective structure of resemblance through a series of examples projected onto the literary and artistic productions. This study will serve as ruminations on the fact that your life is being existent in 'chiasme' of mutual entanglement between the self and the world by investigating relations between a person who sees and a person who is seen, in other words, relations between the perceiving subject and the eyes of others reflected in a mirror.

• Polymer(Korea)
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• v.36 no.4
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• pp.440-447
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• 2012

The branched copolyester was synthesized and its molecular weight, $T_g$, 1/2 method temperature ($T_{1/2}$) and rheological properties were characterized for the application of toner binder. The linear copolyester had low molecular weight and melt elasticity obtained by dimethylterephthalate (DMT), ethylene glycol (EG) and 2,2-bis(4-(2-hydroxypropoxy) phenyl)propane (HPP). The branched copolyesters prepared with various branching agents such as 2-(hydroxymethyl)-2-ethylpropane-1,3-diol (trimethylol propane, TMP), 2,2-bi(hydroxymethyl)-1,3-propanediol (pentaerythritol, PER), 1,2,4-benzenetricarboxylic anhydride (trimellitic anhydride, TMA) and glycerol to improve the physical properties of the linear copolyester. The effect of branching agents on the molecular weight and melt elasticity of the branched copolyester was examined. The branched copolyesters prepared by adding over 15 mol% of branching agent showed relatively high molecular weight and melt elasticity, and $T_{1/2}$ value of $140^{\circ}C$. Therefore, the highly branched copolyesters were deemed suitable as a hot-melt toner of laser print process.

• Korean Chemical Engineering Research
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• v.44 no.6
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• pp.602-608
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• 2006

Carbon fiber (CF) reinforced papers using polyacrylonitrile (PAN) based CF and wood pulp were prepared by varying the lengths and the concentrations of CF, and the basis weight of paper to investigate adhesive state between CF and pulp, and physical properties and electrical conductivity of the paper. The reinforcement was caused by physical entanglement and adhesion at the interface of the different fibers rather than by chemical bonds. The tear strength and the thickness of the paper increased as increasing the concentration of CF, while the tensile and the burst strength of the paper decreased. The improved dispersion of CF in the paper was obtained from mixing shorter CF, but the maximum electrical conductivity of the paper was gained from mixing 10 mm chopped CF. The electrical conductivity of the paper increased sharply from 2 wt％ to 8 wt％ of CF showing S-curve, and increased linearly as increasing the basis weight of the paper. Therefore, in order to improve the electrical conductivity and the physical property of the paper, the increase of basis weight of the paper is also important as the increase of CF content in the paper.

• Gut and Liver
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• v.12 no.6
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• pp.722-727
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• 2018

Background/Aims: Although endoscopic bilateral stent-instent placement is challenging, many recent studies have reported promising outcomes regarding technical success and endoscopic re-intervention. This study aimed to evaluate the technical accessibility of stent-in-stent placement using large cell-type stents in patients with inoperable malignant hilar biliary obstruction. Methods: Forty-three patients with inoperable malignant hilar biliary obstruction from four academic centers were prospectively enrolled from March 2013 to June 2015. Results: Bilateral stent-in-stent placement using two large cell-type stents was successfully performed in 88.4% of the patients (38/43). In four of the five cases with technical failure, the delivery sheath of the second stent became caught in the hook-cross-type vertex of the large cell of the first stent, and subsequent attempts to pass a guidewire and stent assembly through the mesh failed. Functional success was achieved in all cases of technical success. Stent occlusion occurred in 63.2% of the patients (24/38), with a median patient survival of 300 days. The median stent patency was 198 days. The stent patency rate was 82.9%, 63.1%, and 32.1% at 3, 6, and 12 months postoperatively, respectively. Endoscopic re-intervention was performed in 14 patients, whereas 10 underwent percutaneous drainage. Conclusions: Large cell-type stents for endoscopic bilateral stent-in-stent placement had acceptable functional success and stent patency when technically successful. However, the technical difficulty associated with the entanglement of the second stent delivery sheath in the hook-cross-type vertex of the first stent may preclude large cell-type stents from being considered as a dedicated standard tool for stent-in-stent placement.

• Journal of Korean Philosophical Society
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• v.142
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• pp.145-164
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• 2017

In his Phenomenology of Perception, Merleau-Ponty raises a question of why he has to ask what phenomenology is again. This study assumes that the question can be answered in a new understanding of the "nature" concept and finds its possible grounds in the nature concepts of Schelling and Merleau-Ponty. Schelling and Merleau-Ponty develop philosophical thinking from a critical point of view on the Cartesian and Kantian philosophies "Thing-in-itself" by Kant is, in particular, one of important questions that has to be answered in the philosophy of Schelling since Kant further solidifies a dualistic world by leaving thing-in-itself. Schelling solves the question with the concept of identity and Merleau-Ponty solves the question with body-subject. What we notice in this article is the understanding of Shelling and Merleau-Ponty about nature. Schelling believes there are the creative activities of unconscious intelligence in nature, but spirit or intelligence in his nature concept cannot induce an existential being. Here we see that Schelling is still beyond the traditional epistemological framework. To restore the original nature of nature, we must begin with an understanding of the totality of nature. Nature must also be explained through relationships with humans. Merleau-Ponty shows the entanglement of nature and spirit through the body-subject. In Merleau-Ponty's phenomenology, the body is the equivalent of nature. Understanding the forces of nature that Schelling and Merleau-Ponty are trying to show, and at the same time explaining the problem of how the mind or human beings emerge from nature, we will be able to discover the true nature of nature.