• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.1
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• pp.116-123
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• 2019

Thermal batteries are also called molten-salt batteries as the electrolyte is mainly composed of molten salt. The molten-salt electrolyte is a solid that does not conduct electricity at room temperature, but when it is melted by a pyrotechnic heat source, it becomes an excellent ionic conductor. Thermal batteries are a kind of pyrotechnic battery because they operate only when the solid electrolyte is melted by the heat energy provided by pyrotechnic materials. Pyrotechnic components used in a thermal battery include heat sources, fuse strips, and an igniter. The reliability of these pyrotechnic components critically affects the reliability and performance of the battery that must supply electricity stably to guided munitions even under extreme environmental conditions. Different igniter types offer different advantages: notch-type igniters offer improved ignition probability, whereas film-type igniters offer improved safety. The addition of metal oxides to the heat paper could improve the burn rate, and the ignition reliability could be greatly improved by using it with a flame igniter at the same time. Using a two-step reduction process, high-purity Fe particles in coral form can be safely obtained.

• Composites Research
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• v.32 no.1
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• pp.65-70
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• 2019

The aircraft composites wing parts are usually integrated with adhesive or fastener. These laminated composites have weak interlaminar strength, which can lead to delamination. In order to compensate the disadvantages of laminated composites, it is possible to improve the strength, durability, shock and fatigue resistance by reinforcing the fiber in the thickness direction. In addition, using a single structure near-net-shape saves the manufacturing time and the number of fasteners, thus can reduce the overall cost of the composite parts. In this study, compression test, tensile test and open-hole tensile test are carried out for three structural architecture of 3D (three-dimensional) textile preforms: orthogonal(ORT), layer-to-layer(LTL) and through-the-thickness(TTT) patterns. Among these, the orthogonal textile composite shows the highest Young's modulus and strength in tensile and compression. The notch sensitivity of the orthogonal textile composite was the smallest as compared with UD (unidirectional) and 2D (two-dimensional) fabric laminates.

• (The) Research of the performance art and culture
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• no.42
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• pp.257-290
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• 2021

The Wonju Nongyo (agricultural work song) is geographically classified as eastern minyo (folk song) which has many distinctive, regional features such as tunes, forms and the use of a melodic line. There has been growing attention to the transmission value of the nongyo including the Wonju Eorirang of the Wonju Origol Nongyo and its region of origin. The Wonju Nongyo is of great value and worthy of preservation in the western part of Gangwon Province. For this reason, it seems fairer to say that a focus should be directed towards establishing the identity of the song and increasing the contextualisation of transmission. At the same time, the preservation association's efforts in passing the traditional song down and education activities fairly deserve equal attention. In addition to the way the folk songs are handed down, a discussion on the facilitation of their use will be required. An in-depth discussion about the restoration and use of the song will be encouraged in a multifaceted manner. Unfortunately, few of the previous literatures on nongyo has gone so far as to investigate Arirang as a separate research topic. In fact, the Wonju Origol Nongyo should be viewed as an intangible cultural asset that paved the way for performance artistry of the Korean agricultural work songs to be seen at a national folk art festival. From the perspective of regional characteristics (traditionally termed "tori"), the Wonju Eorirang represents the cultural value of the manners and customs of our locals which constitute unwritten and neglected literary property and musicality of the song. Particularly, a more attention should be paid to making a record of woodcutters and diversity of farmers' small cooperative groups. The existence of the Wonju Eorirang indicates that the melodies to which the song are sung in Nongyo are of infinite variety. A minyo-singer unfolds various journeys of life through various modes and structure of epic chants, ranging from first encounter, love to marriage, realistic problems to relationship with husband's family and death. The epic chant of the Wonju Origol Nongyo contains a rich variety of regional sentiments about life. In particular, the epic chants of the Galtteukgisor and Ssoeltteukgisori are a genius example of sexual satire and a sense of humor. In the past, the agricultural work songs were rhythmic songs served to synchronize physical movements in groups, coordinating tasks in upland farming and rice paddy with the usage of catchy, repetitive verses easy to pass down. The Wonju Origol Nongyo is a precursor of the work songs which took the farming activities a notch higher to be part of the excitement and festivals. In the context of transmission, a festival serves to demonstrate the value of history and life. The value of the Wonju Eorirang should be appreciated and a concerted effort should be made to find a way to facilitate the transmission of the folk song. A folk-singer is a traditional oral poet and a storyteller of minyo and the forms and species of melody solely depend on the signer. The combination of performance and witticism is shown by the singer freely expressing himself. The Origol Nongyo symbolizes ethnic arts cleverly combining playful effects such as tune, rhythm and old agricultural work of the region. It is to be hoped that much of the efforts is directed to designating such folk songs as the archetype of a cultural heritage. In terms of the foundation on which the folk songs are transmitted, the usage(Performance Content) of a community would be an alternative.