• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.9
• /
• pp.488-494
• /
• 2019

Precision Guided Missiles after production and militarization have various characteristics that enable the final performance to be identified by conducting live-fire tests after long-term storage. Likewise, the performance and reliability of ${\bigcirc}{\bigcirc}$ Missiles, which are currently used by the Korean Navy, are also verified consistently by conducting live-fire tests after militarization. Specially, the live fire test at '00 year, which was conducted by Korean Navy, showed the result that 'Ring', which is a component of the canister's front cover, was jammed with wings for propulsion and then broke away from the canister during the missile launch process. This situation led to an interruption of the deployment of wings and finally affected the missile's flight performance. The results of a survey of the canisters of those missiles whose live fire tests were conducted successfully, based on the live fire test at '00 year, showed the 'Ring's separation from canisters. This raises recognition for the need to solve the problems of 'Ring's separation and breakaway. This study suggests an improvement derived by the result of live-fire tests and introduces the effect of final launch performance of ${\bigcirc}{\bigcirc}$ Missiles and test result after applying the improvement.

• Proceedings of the Korea Technology Innovation Society Conference
• /
• 2005.05a
• /
• pp.182-201
• /
• 2005

항공우주산업의 선도적 기술혁신은 타 산업으로 연계 파급 효과가 매우 클 뿐 아니라 역으로 연관산업의 발전이 없이는 기술적 우위를 확보하기 어렵다. 항공우주산업이 높은 기술파급효과를 가지는 이유는 수백만 개의 부품을 퍼즐처럼 조립하는 전형적 복합체계종합산업이기 때문이다. 때문에 기술체계가 매우 복잡하고 관련된 산업 기술 분야 또한 매우 넓다. 항공우주 부품의 생산과정이 매우 복잡하고 엄격한 안전규정을 충족해야 하기 때문에 모기업에 대한 의존도가 높은 강한 가치사슬 구조를 지니게 된다. 항공기 개발 산업은 설계, 생산, 자본재 조달에 있어 계약 관계에 크게 의존한다. 수요특성 면에서는 군 또는 대형 항공사가 주된 수요자로서 상당히 높은 수요독점력(monopsony power)을 지니고 있어 관련 업체(Player)간 협상을 통해 계약관계가 형성된다. 계약 관계는 거래 당사자간의 흥정 또는 협상을 통한 게임으로 지배되는 경향이 많아 상호 정보의 교류는 매우 필수적이다. 항공우주산업 완제품 획득에 있어 체계종합과 부품소재 간의 효율적 연계는 매우 중요한 문제이다. 그럼에도 불구하고 필요기술과 그 소요시점에 있어 부품소재 개발자와 체계설계자는 서로 상이한 시각을 지나고 있다. 양자간의 차이점을 밝히고 전략적 연결점을 제안함이 본 연구의 주제이다. 본 연구는 2004년 산업자원부와 한국산업기술재단이 작성한 항공우주산업기술로드맵의 결과를 바탕으로 항공기 개발 과정에 있어 체계설계와 수많은 부품간의 관계를 파악하고 전략적 시사점을 제시하고자 한다.

• Korean Journal of Environmental Biology
• /
• v.24 no.4
• /
• pp.392-407
• /
• 2006

This study was seasonally undertaken to investigate the benthic polychaetous community along the South-eastern coast of Geoje Is., in February 2004 to November. The macrobenthic fauna showed mean density of 953 md. $m^{-2}$ in February, 1,193 ind. $m^{-2}$ in May, 1,130 ind. $m^{-2}$ in September and 991 ind. $m^{-2}$ in November. Major faunal groups are polychaetes, crustaceans and mollusks, corresponding to 81.6%, 7.9%, 7.0% in total mean density during the sampling seasons, respectively. There was significant difference (two-way ANOVA, p<0.001) among stations in densities of polychaetes. But no significant relationship could be found between the densities of polychaetes and sampling seasons (two-way ANOVA, p>0.05). The density and the species number of polychaetes were high in the coastal area near the Jisepo port, independent of sampling seasons. Several indicator species for the organically enriched environments such as Lumbrineris longifolia, Tharyx sp., Heteromastus filiformis showed high densities during all study periods. Also Magelona japonica included in Ecolgical group I was the most abundant in the whole study period except for February. Cluster analysis on the basis of the species composition showed that the study area could be divided into 3 regions. The density of benthic polychaetes in the coastal area near Jisepo was higher than that in the other assemblages of the study area, due to some predominant opportunistic species, such as Lumbrineris longifolia, Tharyx sp. and Heteromastus filiformis. In addition, the two-way ANOVA showed significant differences among the distribution of AMBI (AZTI's Marine Biotic Index) values, both in sampling stations (p<0.001) and seasons (p<0.01). According to the classification proposed by Borja et at. (2000), the study area was slightly disturbed site.

• Journal of the Korean earth science society
• /
• v.36 no.3
• /
• pp.222-235
• /
• 2015

Samples were collected from both places including the coastal area within the height of 5 m above the mean sea level (msl) (DH) and the top of the coastal terrace of 10-15 m msl (KS) high in Gwangseungri, Gochanggun, Korea. To find the origin of the deposit in the coastal area, granulometric analysis and geochemical analysis were performed. The result showed that the DH samples were originated from the reddish soils overlaying weathered bedrock which presented gradual change of chemical composition from the bottom toward the top. Clay minerals were found from the DH samples. These results concluded that the DH samples were found as in-situ weathered materials. The KS samples were originated from the soil layer covering gravel layer at the foot slope of the hill along the coast. The KS samples contained different chemical compositions from the DH. It is inferred that some of this layer was disturbed or experienced the influx of foreign material. The particle size of the KS samples was different from those found on the beach. The particle size of lower parts of KS site was finer than that on the beach, but the particle size of middle part of the site was coarser than that on the beach. The sorting of the KS site was poorer than that on the beach. Thus, it is inferred that some parts of the layer were formed by short-lived high energy event rather than sustained and continuous action of tidal currents and/or waves. Analysis using an optically stimulated luminescence (OSL) method showed that the burial age of samples from KS site were found 0.65-0.71 ka. Though the characteristics of the sediment layer and forming event in this area should be further studied, it can be inferred that this sedimentary layer formed by coastal flooding with storm.

• Journal of Wetlands Research
• /
• v.6 no.1
• /
• pp.57-72
• /
• 2004

Macrobenthic fauna were studied on a tidal flat in Garolim Bay in July 2002, in order to understand their spatial distribution with the surface sediment types. Forty-nine stations were set on the tidal flat. A total of 147 species was sampled with the mean density of $1,140ind./m^2$ and the mean biomass of $157.2g/m^2$. The polychaetes were speices- and density-dominant faunal group with 64 species and the mean density of $791ind./m^2$. Mollusks were biomass-dominant faunal group with $132.0g/m^2$. Major dominant species were two polychaetes, Mediomastus californiensis with the mean density of $374ind./m^2$ and Heteromastus filiformis with $224ind./m^2$. Also mollusks such as Umbonium thomasi, Batillaria cumingi and Ruditapes philippinarum was relatively high in the mean density, showing the density of 45, 42, $32ind./m^2$ respectively. Especially, U. thomas was distributed in the mouth of the bay, where sediment grain size is rather coarse, and R. philippinarum at near tidal channel. Based on the cluster analysis, the macrobenthic community on the tidal flat was classified into seven station groups depending on the benthic environmental parameters(sediment types). Compared with other Korean tidal flats, species richness of Garolim tidal flats is more and less low.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.3
• /
• pp.321-327
• /
• 2020

Engine oil leaks comprise the largest percentage of the major quality problems that have occurred during the engine production process for military land system equipment over the last two years. To minimize this, it is essential to understand the root cause of the engine oil leakage and perceive the more common leakage area, as well as reduce the quality costs of pre-identification for leaks in the engine assembly process and single items. Therefore, in this study, the mass production quality of engines installed and operated in power equipment was improved by visualizing the engine oil leakage injected with the fluorescent dye and increasing the identification of the engine oil leak phenomenon. For this reason, the possibility of substituting the engine oil was considered and the engine oil was injected with the fluorescent dye. The maintenance was improved by reforming the engine oil injection process and leakage inspection process. Finally, these results suggest that the quality costs between mass production processes can be minimized by ensuring the reliability of military engines by reducing the user's complaints and improving the quality control capabilities of engine manufacturers.

• The Journal of the Korea Contents Association
• /
• v.19 no.7
• /
• pp.360-375
• /
• 2019

This paper tries to study the ecosystem after constructing the network of the continuing transactions associated with distribution industry with the data of more than 50 thousands firms provided by the Korean enterprise data (KED) for 2015. After applying the clustering method, one of social network analysis tools, we find the firms in the network grouped into 732 clusters occupying about 80% of whole distribution industry sales in KED data. The firms in a cluster have most of their transactions with other firms in the cluster. But the clusters have smaller firm numbers in the cluster and sales portion of the biggest firms in the industry than the case of the manufacturing industry. The Input-output analysis for the biggest distribution firms show that the small and medium size enterprise(SME)s have very high sale dependency on a main firm in some clusters. This fact implies more efficient fair transaction policies within the clusters. And small number of big distribution firms have very high rear production linkage effects on SMEs or on the 10th or 31th group with high portion of SME employment. They should be considered important in the SME growth and employment policies.

• The Journal of Korean Academy of Prosthodontics
• /
• v.56 no.3
• /
• pp.179-187
• /
• 2018

Purpose: The purpose of this study was to investigate the effect of heat applied to disintegrate cement on the removal torque value and fracture strength of titanium abutment and abutment screw. Materials and methods: Implants, titanium abutments and abutment screws were prepared for each 20 piece. Implant abutments and screws were classified as the control group in which no heat was applied and the experimental group was heated in a vacuum furnace to $450^{\circ}C$ for 8 minutes and cooled in air. The abutments and screws were connected to the implants with 30 Ncm tightening torque at interval 10 minutes and the removal torque value was measured 15 minutes later. And the fracture strength of abutment screw was measured using universal testing machine. Results: The mean removal torque value was $27.84{\pm}1.07Ncm$ in the control group and $26.55{\pm}1.56Ncm$ in the experimental group and showed statistically significant difference (P < .05). The mean fracture strength was $731.47{\pm}39.46N$ in the control group and $768.58{\pm}46.73N$ in the experimental group and showed statistically no significant difference (P > .05). Conclusion: The heat applied for cement disintegration significantly reduced the removal torque value of the abutment screw and did not significantly affect fracture strength of the abutment screw. Therefore, in the case of applying heat to disintegrate cement it is necessary to separate the abutment screw or pay attention to the reuse of the heated screw. However further studies are needed to evaluate the clinical reuse of the heated screw.

• The Korean Journal of Petroleum Geology
• /
• v.9 no.1_2 s.10
• /
• pp.1-15
• /
• 2001

Hierarchically controlled sequence stratigraphic analysis shows that the Lower Ordovician mixed carbonatesiliciclastic Mungok Formation, Korea consists of three depositional sequences: T1, T2, and T3 in ascending order. Sequence boundaries are generally marked by abrupt transition from coarse-grained shallow-water carbonates to finegrained deeper-water carbonates mixed with fine-grained siliciclastics, and show indication of subaerial exposure such as karstification. Within this sequence stratigraphic framework, facies characteristics indicate that the Mungok sequences were mostly deposited on a subtidal ramp without slope break. The Mungok ramp had been under the influence of frequent tropical storm activity during deposition. The difference in lithology of tempestites seems to have been controlled by the nature of substrates and by proximality. High-frequency cycles consist of upward-shallowing facies successions. Cycles of shallow-water and basinal deposits are not well represented, probably due to cycle amalgamation. Cycle stacking patterns do not show a consistent thickness change that is usually associated with a large-scale sea-level change probably because of unfilled accommodation space.

• The Journal of the Korea Contents Association
• /
• v.17 no.3
• /
• pp.666-674
• /
• 2017

Today, the term of fusion, such as technology convergence and industrial convergence, is emerging as one of the most important trends in our society. The purpose of this study is to analyze the convergence coefficient of each industry using patent data and to analyze the convergence phenomenon in industry based on convergence coefficient. To do this, 2011-2015 Korean patent data were utilized. The research findings revealed that the ICC by industry was the highest in order of man-made fibres, paints/varnishes, petroleum products/nuclear fuel and other chemicals. Also, according to the inter-industry convergence matrix, the number of convergence patents was the greatest in order of office machinery and computers, special purpose machinery industries and Measuring instruments. Added same analysis was conducted through Industry with high number of patents. As a result, the convergence has been actively carried out in the fields of optical instruments, Basic chemical, Fabricated metal products, Measuring instruments and special purpose machine manufacturing industries.