• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.10
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• pp.1049-1056
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• 2014

Microelectronics components contain various materials with different coefficients of thermal expansion (CTE). Although a large amount of published data on the CTE of standard materials is available, it occasionally becomes necessary to measure this property for a specific actual material over a particular temperature range. A change in the temperature of a material causes a corresponding change in the output of the strain gage installed on the specimen because of not only the mechanical load but also the temperature change. In this paper, a detailed technique for CTE measurement based on these thermal characteristics of strain gages is proposed and its reliability is evaluated. A steel specimen, aluminum specimen, and copper specimen, whose CTE values are well known, were used in this evaluation. The proposed technique was successfully applied to the measurement of the CTE of a coreless package substrate composing of electronics packages.

• Journal of KIISE:Computing Practices and Letters
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• v.9 no.3
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• pp.241-253
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• 2003

SCA (Software Communication Architecture), which has been adopted as a SDR(Software Defined Radio) Forum standard, provides a framework that successfully exploits common design patterns of embedded systems software. However, the SCA is inadequate as a component framework since it does not explicitly specify (1) a component model that defines how to express a component interface and how to implement it, (2) a package model that defines what and how to package in deployment units, and (3) a deployment model that defines the deployment environment and deployment process. In this paper, we propose a SCA-based component framework for SDR. Specifically, we present (1) a component model that defines a component as a specialized CORBA object that implements object management functionality, (2) a package model exploiting the existing XML descriptors of the SCA, and (3) a deployment model that defines a SCA-based deployment environment, a boot-up process that restores the deployment state, and a deployment process that supports lazy application instantiation and dynamic component replacement.

• Corrosion Science and Technology
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• v.6 no.6
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• pp.282-285
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• 2007

Smaller size and higher integration of electronic systems make narrower interconnect pitch not only in chip-level but also in package-level. Moreover electronic systems are required to operate in harsher conditions, that is, higher current / voltage, elevated temperature / humidity, and complex chemical contaminants. Under these severe circumstances, electronic components respond to applied voltages by electrochemically ionization of metals and conducting filament forms between anode and cathode across a nonmetallic medium. This phenomenon is called as the electrochemical migration. Many kinds of metal (Cu, Ag, SnPb, Sn etc) using in electronic packages are failed by ECM. Eutectic SnPb which is used in various electronic packaging structures, that is, printed circuit boards, plastic-encapsulated packages, organic display panels, and tape chip carriers, chip-on-films etc. And the material for soldering (eutectic SnPb) using in electronic package easily makes insulation failure by ECM. In real PCB system, not only metals but also many chemical species are included. And these chemical species act as resources of contamination. Model test systems were developed to characterize the migration phenomena without contamination effect. The serpentine-shape pattern was developed for analyzing relationship of applied voltage bias and failure lifetime by the temperature / humidity biased(THB) test.

• The Journal of the Korea Contents Association
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• v.6 no.2
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• pp.17-26
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• 2006

SIP(Session Initiation Protocol)-based centralized conference service model has advantage of easiness in conference management and service as compared to other models. However when media server which is one of the components of conference server is included in the conference server, this model shows disadvantage of high server work load with increasing numbers of conferences and participants. In this paper, to improve this problem, we have suggested and implemented a new conference service model in which an UA(User Agent) who first make the conference acts as a media server instead of conventional conference server and, the conference server with conference event package takes only part of management of the conference and its participants. Therefore, many more conferences can be held and managed compared to the conventional centralized conference service model because load of the conference server decreases in our suggested model md, furthermore the participants needs only make SIP call connections to the UA who first make the conference for establishing media session.

• Journal of Korea Spatial Information System Society
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• v.3 no.1 s.5
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• pp.5-16
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• 2001

ITS (Intelligent Transport System) has been developed into the full service leading to a new life style with the various services from private sector, which was intended to prevent the traffic accidents and to reduce the traffic jams. Since traveler-type components used in ITS services are not exclusively designed. but they can be one of the existing devices such as mobile phone, PDA, PC, KIOSK and etc. We need to consider that these devices are equipped to support ITS related services. Therefore, this study modeled, through UML, a framework of portable components based on the present national ITS architecture; the purpose being that private companies may be able to develop portable components with concepts of ITS services. The methodology of the modeling process we followed consisted of four steps: (1) analyzing service-related subsystems, (2) generalizing equipment-package and functional specifications. (3) describing information and function specific reference models, and (4) UML modeling of the reference model.

• Journal of Welding and Joining
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• v.33 no.3
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• pp.25-31
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• 2015

Due to environmental regulations (RoHS, WEEE and ELV) of the European Union, electronics and automotive electronics have to eliminate toxic substance from electronic devices and system. Specifically, reliability issue of lead-free solder joint have an increasing demand for the car electronics caused by ELV banning. The authors prepared engine control unit and cabin electronics soldered with Sn-3.0Ag-0.5Cu (SAC305). To compare with the degradation characteristics of solder joint strength, thermal cycling test (TC), power-thermal cycling test (PTC) and series tests were conducted. Series tests were conducted for TC and PTC combined stress test using the same sample in sequence and continuously. TC test was performed at $-40{\sim}125^{\circ}C$ and soak time 10 min for 1000 cycles. PTC test was applied by pulse power and full function conditions during 100 cycles. Combined stress test was tested in accordance with automotive company standard. Solder joint degradation was observed by optical microscopy and environment scanning electron microscopy (ESEM). In addition, to compare with deterioration of bond strength of quad flat package (QFP) and chip components, we have measured lead pull and shear strength. Based on the series test results, consequently, we have validated of series test method for lifetime and reliability of Pb-free solder joint in automotive electronics.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.261-267
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• 2020

The demand for faster, lighter, and thinner portable electronic devices has brought about a change in semiconductor packaging technology. In response, a stacked chip-scale package(SCSP) is used widely in the assembly industry. One of the key materials for SCSP is a die-attach film (DAF). Excellent flowability is needed for DAF for successful die attachment without voids. For DAF with high flowability, two-step curing is often required to reduce a cure crack, but one-step curing is needed to reduce the processing time. In this study, DAF composition was categorized into three groups: cure (epoxy resins), soft (rubbers), hard (phenoxy resin, silica) component. The effect of the composition on a cure crack was examined when one-step curing was applied. The die-attach void and flowability were also assessed. The cure crack decreased as the amount of hard components decreased. Die-attach voids also decreased as the amount of hard components decreased. Moreover, the decrease in cure component became important when the amount of hard component was small. The flowability was evaluated using high-temperature storage modulus and bleed-out. A decrease in the amount of hard components was critical for the low storage modulus at 100℃. An increase in cure component and a decrease in hard component were important for the high bleed-out at 120℃(BL-120).

• Management & Information Systems Review
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• v.1
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• pp.193-228
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• 1997

Behaviors of organizational members can be classified as two types. One is behavior required to perform formally given job. The other is a various kind of behavior taken voluntarily but not required directly and formally to perform job. The former can be called as in-job behavior while the latter can be called as extra-job behavior. Many organizational scientists so far, have focused on investigating in-job behavior. Yet, from a decade, organizational researchers have recognized that in-job behavior alone can not explain sufficiently job performance or organizational effectiveness Thus. they have paid attention to extra-job behavior, which is generally called as organizational citizenship behavior. Existing studies of organizational citizenship behavior have three types : First type is studying the concept and components of organizational citizenship behavior. Second tope is studying the determinants of organizational citizen-ship behavior and relationships with it. And third type is studying relatioships between organizational citizenship behavior and job performance. This study, therefore, have purposes as follows : Firstly, this study designs a comprehensive model in the below figure and generates inclusive hypotheses about relationships among antecedents, intermediate factors, and the components of organizational citizenship behavior. Secondly, this study investigating empirically such relationships and draws a picture of mediation roles of the intermediate variables. To design the model and generate the hypotheses, this study conducted a comprehensive literature survey on organizational citizenship behavior. To test the hypotheses, this study collected data from 847 employees at 12 large genral hospitals in Pusan area through a questionnaire survey and conducted the three step mediated regression analysis using the SAS-PC Package.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.1
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• pp.61-67
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• 2010

The chemical components in plant cuticular wax can be used as markers to estimate the species composition of the diet of grazing animals. In this experiment, composition of the diet of yak on the Qinghai-Tibetan plateau was estimated using n-alkane analysis. During the grazing period, samples of whole plants of the species present, plus fecal samples voided by the yak, were collected, air-dried and ground prior to the extraction of cuticular wax n-alkanes. The species composition of the yak diets was estimated by relating fecal alkane contents to those of the plant species, using the 'ATWHAT'software package. The results showed that the n-alkane technique can detect the main dietary components selected by yak. The diet consumed by yak contained 33% Kobresia humilis, 67% Stipa aliena in summer pasture; 26% Potentilla anserine, 74% Carex qinghaiensis in autumn pasture; 52% Carex qinghaiensis, 32% Heteropappus bowerii and 16% Saussurea semifasciata in winter pasture and 5% Carex qinghaiensis, 95% Achnatherum splendens in spring pasture. The apparent selection for forbs is likely to be a reason for nutritional constraint of yak inhabiting alpine environments.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.9
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• pp.3895-3899
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• 2012

In this study, the start-type molded material, silicone resin(RTV-3040) was used to develop a mold that is utilized for embossing pattern. After selecting a required pattern using the commercial package (Freeform), we examined whether this is applicable to components creating projective embossed side on the surface. We responded to products that require corrosive pattern, such as aluminum mold, by making the starting type when small amounts of components are developing. However, the development of silicone mold that is applied to corrosive pattern showed the possible reduction in time and cost.