Sang-goo Lee

A new flash memory management for flash storage system

Proposes a new way of managing flash memory space for flash memory-specific file systems based on a log-structured file system. Flash memory has attractive features such as non-volatility and fast I/O speed, but it also suffers from an inability to update in place, and limited usage cycles. These drawbacks require many changes to conventional storage (file) management techniques. Our focus is on lowering the cleaning cost and evenly utilizing flash memory cells while maintaining a balance between these two often-conflicting goals. The cleaning efficiency is enhanced by dynamically separating cold data and non-cold data. The second goal, cycle leveling, is achieved to the degree where the maximum difference between erase cycles is below the error range of the hardware. Simulation results show that the proposed method has a significant benefit over naive methods: a maximum of 35% reduction in the cleaning cost with evenly-spread writes across segments.

Opinion mining of customer feedback data on the web

As people leave on the Web their opinions on products and services they have used, it has become important to develop methods of (semi-)automatically classifying and gauging them. The task of analyzing such data, collectively called customer feedback data, is known as opinion mining. Opinion mining consists of several steps, and multiple techniques have been proposed for each step. In this paper, we survey and analyze various techniques that have been developed for the key tasks of opinion mining. On the basis of our survey and analysis of the techniques, we provide an overall picture of what is involved in developing a software system for opinion mining.

Random walk based entity ranking on graph for multidimensional recommendation

In many applications, flexibility of recommendation, which is the capability of handling multiple dimensions and various recommendation types, is very important. In this paper, we focus on the flexibility of recommendation and propose a graph-based multidimensional recommendation method. We consider the problem as an entity ranking problem on the graph which is constructed using an implicit feedback dataset (e.g. music listening log), and we adapt Personalized PageRank algorithm to rank entities according to a given query that is represented as a set of entities in the graph. Our model has advantages in that not only can it support the flexibility, but also it can take advantage of exploiting indirect relationships in the graph so that it can perform competitively with the other existing recommendation methods without suffering from the sparsity problem.

SPARQL basic graph pattern processing with iterative MapReduce

There have been a number of approaches to adopt the RDF data model and the MapReduce framework for a data warehouse, as the data model is suitable for data integration and the data processing framework is good for large-scale fault-tolerant data analyses. Nevertheless, most approaches consider the data model and the framework separately. It has been difficult to create synergy because there have been only a few algorithms which connects the data model and the framework. In this paper, we offer a general and efficient MapReduce algorithm for SPARQL Basic Graph Pattern which is a set of triple patterns to be joined. In a MapReduce world, it is known that the join operation requires computationally expensive MapReduce iterations. For this reason, we minimize the number of iterations with the followings. First, we adopt traditional multi-way join into MapReduce instead of multiple individual joins. Second, by analyzing a given query, we select a good join-key to avoid unnecessary iterations. As a result, the algorithm shows good performance and scalability in terms of time and data size.

The effect of nitric oxide on cyclooxygenase-2 (COX-2) overexpression in head and neck cancer cell lines.

The overexpression of cyclooxygenase‐2 (COX‐2) and inducible nitric oxide synthase (iNOS) has been previously reported in head and neck squamous cell carcinoma (HNSCC), as well as in many cancers. We hypothesized that endogenous nitric oxide (NO) might increase the expression of COX‐2 in cancer cells. Therefore, we investigated the cross‐talk between NO and the prostaglandin (PG) pathways in HNSCC cell lines. We found that COX‐2 and iNOS expressions were elevated simultaneously. On adding the NO donor, SNAP, the PGE2 level was increased 2–20 times due to increased COX‐2 expression. This increase of COX‐2 expression by SNAP or PMA (potent inducer of both iNOS and COX‐2) was blocked to various degrees by NO scavengers and NOS inhibitors (L‐NAME and 1400W). Also, the expression of COX‐2 in resting cells was inhibited by NOS inhibitors. Moreover, COX‐2 expression, induced by SNAP, was inhibited by ODQ, a soluble guanylate cyclase (sGC) inhibitor. The effect of dibutyryl‐cGMP on COX‐2 expression was similar to that of SNAP. These results imply that endogenous or exogenous NO activates sGC and that the resulting increase of cGMP induces a signaling that upregulates the expression of COX‐2 in HNSCC cell lines. We also observed that NO increased COX‐2 expression in different cancer cell lines, including cervic and gastric cancer cell lines. These findings further support the notion that NO can be associated with carcinogenesis through the upregulation of COX‐2, and that NOS inhibitor may be also useful for cancer prevention.

Building an operational product ontology system

A base of clearly defined product information is a key foundation for an e-commerce system. The manipulation and exchange of semantically enriched and precise product information can enhance the quality of an e-commerce system and offer a high level of interoperability with other systems. Product information consists of product attributes and the relationships between products. Product categorization (or classification) is one type of such relationships. Ontology can play an important role in the formalization of product information. Although the idea of utilizing ontology for e-Catalogs has been raised before, we are yet to find an operational implementation of applying ontology in the domain. In this paper, we report on our recent effort to build an operational product ontology system for a government procurement service. The system is designed to serve as a product ontology knowledge base; not only for the design and construction of product databases but also for search and discovery of products. Especially, the keyword-based searching over product ontology database demands different techniques from those over conventional document databases or relational databases, and should be designed to reflect particular characteristics of product ontology. We also introduce some other issues that we have experienced in the project, and those issues include product ontology modeling, ontology construction and maintenance, and visualization. Our work presented herein may serve as a reference model for similar projects in the future.

An Ontology-Based Product Recommender System for B2B Marketplaces

An ontology-based product-recommender system can help catalog administrators in B2B marketplaces maintain up-to-date product databases by acquiring mapping information between the new product data and existing data. The proposed approach is keyword-based and independent of the underlying physical structure of product ontology. With a Bayesian belief network as its basis, the ranking algorithm utilizes semantics embedded within relationships defined in ontology to probabilistically determine the ranking scores. The methodology is implemented on a practical ontology system powerful enough to assist users in B2B marketplaces. Its effectiveness is demonstrated in comparison to the conventional search engines.

Mobilenurse: hand-held information system for point of nursing care

Healthcare information travels with patients and clinicians and therefore the need for information to be ubiquitously available is key to reliable patient care and reliable medical systems. We have implemented MobileNurse, a prototype point-of-care system using PDA. MobileNurse has four modules each of which performs: (1) patient information management; (2) medical order check; (3) nursing recording; and (4) nursing care plan. MobileNurse provides easy input interface and various outputs for nursing records. The system consists of PDAs and a mobile support system (MSS) which supports clinical data exchange between PDAs and hospital information system. Two synchronization modules have been developed to keep the patient data consistent between PDAs and MSS. Clinical trials were performed with six volunteered nurses. They tried MobileNurse for 1-day caring-simulated patients. According to the survey after the trials, most of volunteers agreed that MobileNurse is more helpful and convenient than other non-mobile care systems to check medical orders and retrieve the results of recent clinical tests at the bedside. Through the involvement, we found out that ease-to-use interface is the most critical successful factor for mobile patient care systems.

Association of CD47 with Natural Killer Cell-Mediated Cytotoxicity of Head-and-Neck Squamous Cell Carcinoma Lines

Objective: Integrin-associated protein (CD47) binds specifically to the inhibitory receptor signal-regulatory protein. This study was designed to evaluate the role of CD47 in natural killer (NK) cell-mediated cytotoxicity against cancer cells. Methods: Head-and-neck squamous cell carcinoma (HNSCC) cell lines were analyzed for the expression of CD47 and susceptibility to NK cell-mediated killing. Cytolytic activity was assessed by 51Cr-specific release assays and by measuring cytokine production. Results: HNSCC cell lines that had high CD47 expression showed lower levels of NK cytotoxicity than those with low CD47 expression. After pre-treating cells with neutralizing major histocompatibility complex (MHC) class I or anti-CD47 antibodies, NK cell-mediated cytotoxicity against HNSCC cell lines increased. In addition, when CD47 cDNA was transfected into Caco-2 cells, NK cell-mediated cytotoxicity decreased. Conclusion: These findings suggest that CD47 may play an inhibitory role in NK cell-mediated cytotoxicity against cancer cells, implying a possible mechanism of immune escape in human cancer.

Keyword search in relational databases

This paper surveys research on enabling keyword search in relational databases. We present fundamental characteristics and discuss research dimensions, including data representation, ranking, efficient processing, query representation, and result presentation. Various approaches for developing the search system are described and compared within a common framework. We discuss the evolution of new research strategies to resolve the issues associated with probabilistic models, efficient top-k query processing, and schema analysis in relational databases.