Establishment of quality criteria and estimate of shelf-life for yogurt beverage and stirred-type yogurt in Korea

This study was conducted to estimate the shelf-life of yogurt beverage and stirred-type yogurt. Samples of yogurt beverage and stirred-type yogurt were stored at 10, 15, and 25°C during 25-day storage, and quality changes were monitored. The quality limit for the sensory evaluation was set to 5 points on a 9-point hedonic scale. The legal limits for other quality criteria were established based on the ‘Process Criteria and Ingredient Standards of Livestock Products’ issued by the Animal, Plant and Fisheries Quarantine and Inspection Agency (QIA). Regression equations were used to calculate the non-legal quality limits between sensory evaluation (x) and non-legal quality criteria (y). Non-legal quality criteria were excluded from quality criteria used to establish shelf-life which the correlation coefficient (R²) of the regression equation was less than 0.9. The estimated shelf-life was defined as the date when the earliest date among all date of quality limit. This study indicated that the shelf-life of each sample at 10, 15, and 25°C were as follows: 19, 14, and 12 days for yogurt beverage, and 17, 16, and 12 days for stirred-type yogurt, respectively.     

Analysis of microflora in gochujang,Korean traditional fermented food

To identify and characterize the microbial communities in gochujang, a traditional Korean fermented food, the viable cell numbers of total bacteria, halophilic bacteria, fungi, yeasts, halophilic yeasts, and lactic acid bacteria from 7 homemade gochujang samples produced in the Sunchang area and 5 commercial gochujang samples were counted. The variety of microflora in the gochujang samples was evaluated by identifying the isolates via DNA sequence analysis. The viable cell numbers of total bacteria were determined to be in the range of 6–7 log CFU/g, which were higher than those of yeasts. Neither lactic acid bacteria nor fungi were detected in either type of gochujang after aging. A total of 7 genera and 31 species of microorganisms were identified in the gochujang: 29% was identified as Bacillus velezensis, as a major microorganism in gochujang. Under halophilic conditions, Oceanobacillus spp. was detected for the first time.     

Development of a genus-specific PCR combined with ARDRA for the identification of Leuconostoc species in kimchi

With Leuconostoc species being increasingly isolated from many fermented kimchi, a systematic identification of this genus is required, for which an amplified ribosomal DNA restriction analysis (ARDRA) has been developed. This method applies both polymerase chain reaction and restriction pattern analysis using a restriction enzyme. First, using specific primers that were designed from lactic acid bacteria (LAB) sequences, 217 bp specific to LAB was produced. Then, restriction analysis using the MspI was applied to identify these bacteria at the species level. This study demonstrates novel ARDRA technique for the identification of Leuconostoc species was successful in identifying according to the genomic species.     

Resonance-suppressed magnetic field probe for EM field-mapping system

A novel rectangular magnetic field probe is proposed, and calculated and measured results are presented. The proposed probe effectively suppresses the emission/reception of electromagnetic fields from the edge of the ground plane and, as a result, the usable frequency range of the probe is enhanced compared with that of the conventional one. In order to verify the performance of the probe, measured magnitude and phase of the magnetic field with an H/sub xy/ probe are presented from 1 to 7 GHz for two different geometries: microstrip line and bandpass filter for ultrawide-band application. The measurement results agree very well with theoretically predicted field distributions, showing its excellent performances.     

Effect of α-lath size on the mechanical properties of Ti–6Al–4V using core time hydrogen heat treatment

ABSTRACT

When hydrogen is dissolved, brittleness occurs in the material. However, in the case of titanium and titanium alloy, hydrogen can be temporarily dissolved and removed, thereby improving the mechanical properties of titanium and titanium alloy. In this study, Core time Hydrogen Heat treatment (CHH) applies to Ti–6Al–4V alloy to improve mechanical properties. CHH was performed at 800°C and 1000°C for 2?h. Thereafter, dehydrogenation was performed for 2 h at 700°C in vacuum atmosphere to remove residual hydrogen. After the CHH at 800°C, it was found that the α-lath size in the Ti–6Al–4V was narrowed; thereby increasing the Vickers hardness and tensile strength without decreasing in elongation.     

Allocation of QoS connections in MF-TDMA satellite systems: a two-phase approach

We address the problem of providing guaranteed quality-of-service (QoS) connections over a multifrequency time-division multiple-access (MF-TDMA) system that employs differential phase-shift keying (DPSK) with various modulation modes. The problem can be divided into two parts-resource calculation and resource allocation. We present algorithms for performing these two tasks and evaluate their performance in the case of a Milstar extremely high frequency satellite communication (EHF-SATCOM) system. In the resource-calculation phase, we calculate the minimum number of timeslots required to provide the desired level of bit-error rate (BER) and data rate. The BER is directly affected by the disturbance in the link parameters. We use a Markov modeling technique to predict the worst case disturbance over the connection duration. The Markov model is trained offline to generate a transition-probability matrix, which is then used for predicting the worst case disturbance level. We provide simulation results to demonstrate that our scheme outperforms the scheme currently implemented in the EHF-SATCOM system. The resource-allocation phase addresses the problem of allocating actual timeslots in the MF-TDMA channel structure (MTCS). If we view the MTCS as a collection of bins, then the allocation of the timeslots can be considered as a variant of the dynamic bin-packing problem. Because the this problem is known to be NP-complete, obtaining an optimal packing scheme requires a prohibitive amount of computation. We propose a novel packing heuristic called reserve channel with priority (RCP) fit and show that it outperforms two common bin-packing heuristics.     

Towards a cultural user interface generation principles

As ubiquitous computing, and pervasive computing technology are being applied rapidly to the service industry, in the field of HCI, more complex and in-depth research are required at the moment. The efforts to make user experience more valuable using useful multimedia technologies around us, are being made in various parts of the world. In addition to this, generation studies for developing easier and faster UI are being conducted in the field of UI. Until now, the studies have been focused on generation studies using UI pattern models, but smart UI generation development, considering the cultural environment of users, is required. The purpose of this study is to suggest 3-D integrated design principles of modeling, design, and system for the design of cultural user interface generation reflecting the users’ potential culture models. For this, a CTT model was designed based on MB-UID; and a cultural UI generation system architecture was designed by using cultural dimension models and cultural markers. To analyze the cultural factors, CISC (Cultural Index Score for Country) was derived in the process of culture profiling. Then, to verify the design model, culture UI was implemented, targeting the category UI of smartphone app stores.     

Toward secure distributed spectrum sensing in cognitive radio networks [cognitive radio communications and networks]

Cognitive radio is a revolutionary technology that promises to alleviate the spectrum shortage problem and to bring about remarkable improvement in spectrum utilization. Spectrum sensing is one of the essential mechanisms of CR and is an active area of research. Although the operational aspects of spectrum sensing are being studied actively, its security aspects have attracted very little attention. In this paper, we discuss security issues that may pose a serious threat to spectrum sensing. Specifically, we focus on two security threats - incumbent emulation and spectrum sensing data falsification - that may wreak havoc in distributed spectrum sensing. We also discuss methods for countering these threats and the technical hurdles that must be overcome to implement such countermeasures.     

Effects of elastic-plastic properties of materials on residual indentation impressions in nano-indentation using sharp indenter

One of the primary features of nano-indentation technique is that the contact area induced by an indenter is indirectly measured by a relationship between the penetration depth and the known geometry of the indenter.However,this indirect measurement occasionally leads to inaccurate properties of the indented material.The objective of this study is to investigate the effects of E/σr and the strain hardening exponents n of materials on the behaviors of pile-up and sink-in in nano-indentation and to predict n values of materials from the residual indentation impressions.The relations between the residual indentation profile and n value of the indented material were identified by dimensional analysis.Also,they were numerically formulated using FE analysis of nano-indentation for 140 different combinations of elastic-plastic parameters such as E,σy and n.The parameters of hrp/hm,herp/hm,Rr/hm and HOP/Hreal were introduced as various dimensionless parameters to represent and quantify the residual indentation profile after indentation.They were subsequently characterized as dimensionless functions using n and E/σr values.Finally,the validity of these functions was verified through 3D FE analysis of nano-indentation for Al 6061-T6 and AISI 1010 materials.