• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.3
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• pp.100-109
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• 2019

Maintainability indicates the extent to which maintenance can be done easily and quickly. The consideration of maintainability is crucial to reduce the operation and support costs of weapon systems, but if the maintainability is evaluated after the prototype production is done and necessitates design changes, it may increase the cost and delay the schedule. The evaluation should verify whether maintenance work can be performed, and support the designers in developing a design to improve maintainability. In previous studies, the maintainability index was calculated using the graph theory at the early design phase, but evaluation accuracy appeared to be limited. Analyzing the methods of evaluating the maintainability using fuzzy logic and 3D modeling indicate that the design of a system with good maintainability should be done in an integrated manner during the whole system life cycle. This paper proposes a method to evaluate maintainability using SysML-based modeling and simulation technique and fuzzy logic. The physical design structure with maintainability attributes was modeled using SysML 'bdd' diagram, and the maintainability was represented by an AHP matrix for maintainability attributes. We then calculated the maintainability using AHP-based weighting calculation and fuzzy logic through the use of SysML 'par' diagram that incorporated MATLAB. The proposed maintainability model can be managed efficiently and consistently, and the state of system design and maintainability can be analyzed quantitatively, thereby improving design by early identifying the items with low maintainability.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.88-95
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• 2018

Maintainability indicates how easily a system can be restored to the normal state when a system failure occurs. Systems developed to have high maintainability can be competitive due to reduced maintenance time, workforce and resources. Quantification of the maintainability is possible in many ways, but only after prototype production or with historical data. As such, the graph theory and 3D model data have been used, but there are limitations in management efficiency and early use. To solve this problem, we studied the maintainability index of weapon systems using SysML-based modeling and simulation technique. A SysML structure diagram was generated to simultaneously model the system design and maintainability of system components by reflecting the maintainability attributes acquired from the system engineering tool. Then, a SysML parametric diagram was created to quantify the maintainability through simulation linked with MATLAB. As a result, an integrated model to account for system design and maintainability simultaneously has been presented. The model can be used from early design stages to identify components with low maintainability index. The design of such components can be changed to improve maintainability and thus to reduce the risks of cost overruns and time delays due to belated design changes.

• Journal of Advanced Navigation Technology
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• v.26 no.2
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• pp.99-104
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• 2022

Recently, the domestic demand for weapon systems based on aircraft platforms is gradually increasing. In particular, the demand for effective precision guided missile(PGM) which cruises for several hundred kilometers after launch to strike the ground target is rising drastically, but it is in the early stages of development, and research based on it are limited. This paper is a study on the power converter unit(PCU) within PGM which is mounted on an aircraft platform based on MIL-STD-1760, which is an interface between an aircraft and PGM. We investigated the electrical properties and structure of the umbilical connector, and the aircraft/store electrical interconnection system. Also, the focus on the design specifications of the PCU that supplies power were described. This result 3 phase AC input, which is the state for the guided simulation power supply in the state of being mounted on an aircraft that rectification method with power factor correction(PFC) compared to bridge rectifier circuit. In the future, it may be used as a basis for power supply design on aircraft mounted weapon systems.

• Journal of IKEEE
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• v.26 no.3
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• pp.422-429
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• 2022

A light sensor chip requires a small capacity eFuse (electrical fuse) OTP (One-Time Programmable) memory IP (Intellectual Property) to trim analog circuits or set initial values of digital registers. In this paper, 128-bit eFuse OTP IP is designed using only 3.3V MV (Medium Voltage) devices without using 1.8V LV (Low-Voltage) logic devices. The eFuse OTP IP designed with 3.3V single MOS devices can reduce a total process cost of three masks which are the gate oxide mask of a 1.8V LV device and the LDD implant masks of NMOS and PMOS. And since the 1.8V voltage regulator circuit is not required, the size of the illuminance sensor chip can be reduced. In addition, in order to reduce the number of package pins of the illumination sensor chip, the VPGM voltage, which is a program voltage, is applied through the VPGM pad during wafer test, and the VDD voltage is applied through the PMOS power switching circuit after packaging, so that the number of package pins can be reduced.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.388-388
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• 2016

Chemical mist deposition (CMD) of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) was investigated with cavitation frequency f, solvent, flow rate of nitrogen, substrate temperature $T_s$, and substrate dc bias $V_s$ as variables for efficient PEDOT:PSS/crystalline (c-)Si heterojunction solar cells (Fig. 1). The high-speed camera and differential mobility analysis characterizations revealed that average size and flux of PEDOT:PSS mist depend on f, solvent, and $V_s$. The size distribution of mist particles including EG/DI water cosolvent is also shown at three different $V_s$ of 0, 1.5, and 5 kV for a f of 3 MHz (Fig. 2). The size distribution of EG/DI water mist without PEDOT:PSS is also shown at the bottom. A peak maximum shifted from 300-350 to 20-30 nm with a narrow band width of ~150 nm for PEDOT:PSS solution, whose maximum number density increased significantly up to 8000/cc with increasing $V_s$. On the other hand, for EG/water cosolvent mist alone, the peak maximum was observed at a 72.3 nm with a number density of ~700/cc and a band width of ~160 nm and it decreased markedly with increasing $V_s$. These findings were not observed for PEDOT:PSS/EG/DI water mist. In addition, the Mie scattering image of PEDOT:PSS mist under white bias light was not observed at $V_s$ above 5 kV, because the average size of mist became smaller. These results imply that most of solvent is solvated in PEDOT:PSS molecule and/or solvent is vaporized. Thus, higher f and $V_s$ generate preferentially fine mist particle with a narrower band width. Film deposition occurred when $V_s$ was impressed on positive to a c-Si substrate at a Ts of $30-40^{\circ}C$, whereas no deposition of films occurred on negative, implying that negatively charged mist mainly provide the film deposition. The uniform deposition of PEDOT:PSS films occurred on textured c-Si(100) substrate by adjusting $T_s$ and $V_s$. The adhesion of CMD PEDOT:PSS to c-Si enhanced by $V_s$ conspicuously compared to that of spin-coated film. The CMD PEDOT:PSS/c-Si solar cell devices on textured c-Si(100) exhibited a ${\eta}$ of 11.0% with the better uniformity of the solar cell parameters. Furthermore, ${\eta}$ increased to 12.5% with a $J_{sc}$ of $35.6mA/cm^2$, a $V_{oc}$ of 0.53 V, and a FF of 0.67 with an antireflection (AR) coating layer of 20-nm-thick CMD molybdenum oxide $MoO_x$ (n= 2.1) using negatively charged mist of 0.1 wt% 12 Molybdo (VI) phosphoric acid n-Hydrate) $H_3(PMo_{12}O_40){\cdot}nH_2O$ in methanol. CMD. These findings suggest that the CMD with negatively charged mist has a great potential for the uniform deposition of organic and inorganic on textured c-Si substrate by adjusting $T_s$ and $V_s$.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.32 no.3
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• pp.277-286
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• 1987

Abscisic acid (ABA) content of the seed and endocarp during stratification were analyzed and then examined in relation to the embryo growth and germination. In mature red fruitlet, the ABA content was remarkably higher in sarcocarp than those in both seed ans endocarp. During the stratification before dehiscence, ABA content was gradually decreased in both seed and endocarp. After 90 days(dehiscent percentage; 96%) it came to 90 pmol/ g DW(69% decrease) and to 41 pmol/ g DW (80% decrease) in seed and in endocarp, respectively. The ratio of free from to total ABA content showed constant decrease in seed, but remained at higher level in endocap than in seed. Correlation between the decrease of ABA content and embryo growth showed higher significance in seed than in endocarp. During the stratification after dehiscence, ABA content in seed was gradually decreased at 4$^{\circ}C$ and 15$^{\circ}C$, After 90 days it came to 28 pmol/ g DW (69% decrease) and to 46 pmol/ g DW (49% decrease) at 4$^{\circ}C$ and at 15$^{\circ}C$, respectively. The ratio of free form to total ABA content was gradually increased at 4$^{\circ}C$, but remained almost constant at 15$^{\circ}C$. Correlation between the decrease of ABA content and days to first germination showed positive singificance only at 4$^{\circ}C$, whereas the correlation between the decrease and mean germination percentage per day showed negative significance at 4$^{\circ}C$, but positive significance at 15$^{\circ}C$. The above results indicate the ABA of the seed end endocarp during the stratification before dehiscence seems to be concerned with the immature embryo growth, but that of the seed during the stratification after dehiscence seems to show little effect on the germination capability(degree of breaking physiological dormancy).