• Korea journal of population studies
• /
• v.19 no.1
• /
• pp.73-92
• /
• 1996

There are basically three approaches of surveys on the economically active population, namely Labor Force Approach (or Current Status Approach), Usual Status Approach, and Gainful Worker Approach. The selection of an approach among these approaches to be applied to a survey or population census should take into considerations the purpose and background of the survey or the census and the socio-economic situation of a country. In the Korean Population and Housing Census series which have been taken almost every five years since its first round in 1925, a sample survey on the economically active population has been adopted since the 1960 round of census. Even if the labor force approach continued to be applied to the censns prior to 1980, the approach has been different from one round to another in recent rounds. It may be suggested that the labor force approach continue to be adopted for the Korean Population and Housing Census for the following reasons: 1) the proportion of seasonal workers to the total workers is very small, 2) the proportion of population whose type of activity for a specific duration is different from that for one year is small, 3) the approach for the census should be the same as that for a variety of sample surveys on the economically active population which adopt the labor force approach, since the census functions as a population as well as a bench mark for those sample surveys, 4) an application of labor force approach will facilitate international comparisons since most of countries that conduct a population census adopt this approach, 5) the labor force approach can improve the reliability of results, thanks to its short reference period, etc.

• Journal of Broadcast Engineering
• /
• v.13 no.6
• /
• pp.828-837
• /
• 2008

We propose a method to select representative views of single objects and classes of objects for 3D object retrieval and classification. Our method is based on projected 2D shapes, or views, of the 3D objects, where the representative views are selected by applying affinity propagation to cluster uniformly sampled views. Affinity propagation assigns prototypes to each cluster during the clustering process, thereby providing a natural criterion to select views. We recursively apply affinity propagation to the selected views of objects classified as single classes to obtain representative views of classes of objects. By enabling classification as well as retrieval, effective management of large scale databases for retrieval can be enhanced, since we can avoid exhaustive search over all objects by first classifying the object. We demonstrate the effectiveness of the proposed method for both retrieval and classification by experimental results based on the Princeton benchmark database [16].

• Journal of KIISE:Computer Systems and Theory
• /
• v.36 no.6
• /
• pp.476-487
• /
• 2009

The virtual memory system in 4.4 BSD operating systems exploits a clustering scheme to reduce disk I/Os in paging out (or flushing) modified pages that are intended to be replaced in order to make free rooms in memory. Upon the page out of a victim page, the scheme stores a cluster (or group) of modified pages contiguous with the victim in the virtual address space to swap disk at a single disk write. However, it fails to find large clusters of contiguous pages if applications change pages not adjacent with each other in the virtual address space. To address the problem, we propose a new clustering scheme called Multiple-Object Clustering (MOC), which together stores multiple clusters in the virtual address space at a single disk write instead of paging out the clusters to swap space at separate disk I/Os. This multiple-cluster transfer allows the virtual memory system to significantly decrease disk writes, thus improving the page-out performance. Our experiments in the FreeBSD 6.2 show that MOC improves the execution times of realistic benchmarks such as NS2, Scimark2 SOR, and nbench LU over the traditional clustering scheme ranging from 9 to 45%.

• Korean Journal of Optics and Photonics
• /
• v.8 no.6
• /
• pp.510-515
• /
• 1997

Packaging takes an extremely important element of optical module cost due primarily to the added complication of alignment between semiconductor devices and optical fiber, and many efforts have been devoted on reducing the cost by eliminating the complicated optical alignment procedures in passive manner. In this study, we fabricated silicon optical benches on which the optical alignments are accomplished passively. To improve the positioning accuracy of a flip-chip bonded LD, we adopted fiducial marks and solder dams which are self-aligned with V-groove etch patterns, and a stand-off to control the height and to improve the heat dissipation of LD. Optical sub-assemblies exhibited an average efficiency of -11.75$\pm$1.75 dB(1$\sigma$) from the LD-to-single mode fiber coupling and an average sensitivity of -35.0$\pm$1.5 dBm from the fiber and photodetector coupling.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.30 no.7C
• /
• pp.726-734
• /
• 2005

Traditional watermarking technologies are symmetric method which embedding and detection keys are the same. Although the symmetric watermarking method is easy to detect the watermark, this method has weakness against to malicious attacks remove or modify the watermark information when the symmetric key is disclosure. Recently, the asymmetric watermarking method that has different keys to embed and detect is watched by several researchers as a next generation watermarking technology. In this paper, hybrid asymmetric watermarking algorithm is proposed. This algorithm is composed of correlation detection method and critical criteria method. Each method can be individually used to detect watermark from a watermarked content. Hybrid asymmetric detection is complement between two methods, and more feasible than when each method is used respectively, Private key and public key are generated by secure linear transformation and specific matrix. As a result, we have proved the proposed algorithm is secured than symmetric watermarking algorithms. This algorithm can expand to multi bits embedding watermark system and is robust to JPEG and JPEG2000 compression.

• Korean Journal of Remote Sensing
• /
• v.37 no.5_2
• /
• pp.1235-1243
• /
• 2021

Geostationary Ocean Color Imager 2 (GOCI-II) on Geo-KOMPSAT-2 (GK2B)satellite was developed as a mission successor of GOCI on COMS which had been operated for around 10 years since launch in 2010 to observe and monitor ocean color around Korean peninsula. GOCI-II on GK2B was successfully launched in February of 2020 to continue for detection, monitoring, quantification, and prediction of short/long term changes of coastal ocean environment for marine science research and application purpose. GOCI-II had already finished IAC and IOT including early in-orbit calibration and had been handed over to NOSC (National Ocean Satellite Center) in KHOA (Korea Hydrographic and Oceanographic Agency). Radiometric calibration was periodically conducted using on-board solar calibration system in GOCI-II. The final calibrated gain and offset were applied and validated during IOT. And three video parameter sets for one day and 12 video parameter sets for a year was selected and transferred to NOSC for normal operation. Star measurement-based INR (Image Navigation and Registration) navigation filtering and landmark measurement-based image geometric correction were applied to meet the all INR requirements. The GOCI2 INR software was validated through INR IOT. In this paper, status and results of IOT, radiometric calibration and INR of GOCI-II are analysed and described.