• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.05a
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• pp.143-149
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• 2002

Ball reducer with waved grooves has many advantages over other reducers for the high-reduction ratios, low noise and low energy loss, etc. The mechanism of force transmission is very similar to that of cam and follower in automobile valve train system especially in the contact geometry. In this study, we have investigated the traces of contact between ball and outer race and the working behaviors with a certain reduction ratio. In order to verify the contact behaviors between ball and outer race, which determines the critical endurance life the contact velocity and load are computed for a cycle. During some period of a cycle, the contact velocity reverses its direction very suddenly, which causes undesirable endurance performance of this machinery. From the computational investigation in this work, we hope to predict similar contact damages in other machinery due to this kind of contact behaviors, which is very common in many contact phenomena.

• Korean Journal of Applied Biomechanics
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• v.28 no.2
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• pp.93-100
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• 2018

Objective: The purpose of this study is to analyze the kinematic characteristics of the national speed skaters in the curve phase of 500-m race. Method: Seven national skaters participated in the study. Race images were acquired using a high - speed camera, and the three-dimensional motion was analyzed. Results: For skaters, whose average velocity in the curve phase is high, the velocity of entry into the straight phase was also fast. The fast skaters showed a larger maximum angle of extension of the knee joints than the relatively slow skaters, and the trunk ROM was smaller. Fast skaters tended to match the timing of the movement of the lower limb with the pelvis, while slow skaters tended to rotate the left pelvis backward. The velocity of the curve phase did not show a clear relationship with stroke time, average trunk angle, and lap time. Conclusion: It is important to skate close to the inner line, keep the trunk ROM below 10 degrees, extend the knee angle to over 160 degrees, and match the movement of the pelvis and lower limb to accelerate in the curve phase. The average velocity of the curves was fast for many athletes, but the competition rankings were low. Therefore, it is possible to improve the performance by optimizing the start technique, the running characteristics of the straight phase, and the physical factors.

• Journal of Animal Science and Technology
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• v.66 no.2
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• pp.425-437
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• 2024

Exercise plays an important role in regulating energy homeostasis, which affects the diversity of the intestinal microbial community in humans and animals. To the best of the authors' knowledge, few studies have reported the associations between horse gut microbiota along with their predicted metabolic activities and the athletic ability of Jeju horses and Thoroughbreds living in Korea. This study was conducted to investigate the association between the gut microbiota and athletic performance in horses. This study sequenced the V3 and V4 hypervariable regions of the partial 16S rRNA genes obtained from racehorse fecal samples and compared the fecal microbiota between high- and low-performance Jeju horses and Thoroughbreds. Forty-nine fecal samples were divided into four groups: high-performance Jeju horses (HJ, n = 13), low-performance Jeju horses (LJ, n = 17), high-performance Thoroughbreds (HT, n = 9), and low-performance Thoroughbreds (LT, n = 10). The high-performance horse groups had a higher diversity of the bacterial community than the low-performance horse groups. Two common functional metabolic activities of the hindgut microbiota (i.e., tryptophan and succinate syntheses) were observed between the low-performance horse groups, indicating dysbiosis of gut microbiota and fatigue from exercise. On the other hand, high-performance horse groups showed enriched production of polyamines, butyrate, and vitamin K. The racing performance may be associated with the composition of the intestinal microbiota of Jeju horses and Thoroughbreds in Korea.

• Asian-Australasian Journal of Animal Sciences
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• v.31 no.3
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• pp.309-315
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• 2018

Objective: This study aimed to test the expression patterns of ERBB receptor feedback inhibitor 1 (ERRFI1) before and after exercise and the association of non-synonymous single-nucleotide polymorphisms (nsSNPs) of horse ERRFI1 with racing traits in Thoroughbreds. Methods: We performed bioinformatics and gene expression analyses for horse ERRFI1. Transcription factor (TF) binding sites in the 5'-regulatory region of this gene were identified through a tool for prediction of TF-binding site (PROMO). A general linear model was used to detect the association between the nsSNP (LOC42830758 A to G) and race performance. Results: Quantitative polymerase chain reaction analysis showed that expression level of ERRFI1 after exercise was 1.6 times higher than that before exercise. Ten transcription factors were predicted from the ERRFI1 regulatory region. A novel nsSNP (LOC42830758 A to G) was found in ERRFI1, which was associated with three racing traits including average prize money, average racing index, and 3-year-old starts percentile ranking. Conclusion: Our analysis will be helpful as a basis for studying genes and SNPs that affect race performance in racehorses.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.12
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• pp.1529-1538
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• 1999

광대역 액세스 망은 B-ISDN 환경에서 다양한 유형의 가입자들을 서비스 노드로 집선하는 기능을 수행한다. ITU-T의 SG13에서는 광대역 액세스 망과 서비스 노드 사이에서 ATM 자원의 동적인 할당 및 해제를 위하여 연결 제어 프로토콜의 표준화를 수행하고 있다. ATM 연결의 설정을 위한 연결 제어 프로토콜과 신호 프로토콜의 연동 기능은 서비스 노드에서 수행되며, ITU-T에서는 순차적 연동 모델을 채택하고 있다. 순차적 연동 모델은 SN에서 각 프로토콜의 절차가 순차적 방식으로 연동되므로 연결 지연이 크다. 본 논문에서는 광대역 액세스 망의 도입으로 인한 연결 설정 지연을 최소화하기 위하여 병렬형으로 수행되는 연동 모델을 제시하였다. 그리고 본 논문에서 제안한 병렬형 연동 모델의 성능 분석을 통하여 순차적 연동 모델과의 연결 설정 지연 및 완료비에 대한 비교, 분석을 수행하였다. 성능 분석에서 사용된 워크로드 파라미터는 RACE MAGIC 프로젝트의 결과를 적용하였다. Abstract In B-ISDN environment, various subscribers are concentrated into a service node via a broadband access network. The SG13 of ITU-T is standardizing a connection control protocol which provides dynamic allocation of ATM resources between an access network and a service node. To establish an ATM connection, interworking functions between the connection control protocol and the signaling protocol are performed at the service node. ITU-T adopts the sequential interworking model. In this paper, we propose the parallel interworking model which minimizes the overall connection setup delay by introducing the access network. Using the performance analysis, we compare our proposed parallel model with the existing sequential model in terms of connection setup delay and completion ratio. The workload parameters of RACE MAGIC project are applied to the analysis and simulation.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.8
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• pp.884-894
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• 1999

순서적 동기화 및 내포 병렬성을 포함하는 공유메모리 병렬 프로그램에서의 경합(race)은 프로그램 수행에서 원하지 않은 비결정성(nondeterminism)을 야기할 수 있기 때문에 반드시 탐지되어져야 한다. 특히 프로그램 수행에서 최초경합(first race)을 탐지하는 것은 중요한데, 그 이유는 이 경합을 제거하면 다른 경합이 나타나지 않을 수도 있기 때문이다. 본 논문에서는 결정적 공유메모리 병렬프로그램을 위한 2단계 수행중 (two-pass on-the-fly) 최초경합 탐지 기법을 제시하며, 이것은 공유메모리 병렬 프로그램의 특정 수행에서 "최초로 발생되는" 경합들을 탐지하는 기법이다. 그리고 HPF 컴파일러를 이용하여 본 탐지 프로토콜을 공인된 벤치마크 프로그램에 적용하여, 병렬 프로그램 디버깅 시 고려하여야 할 파라미터들에 대한 실험으로부터 본 기법의 효율성을 보였다.Abstract Detecting races is important in debugging shared-memory parallel programs which have ordered synchronization and nested parallelism, because the races result in unintended non- deterministic executions of the programs. The first races are important in debugging, because the removal of such races may make other races disappear. It is even possible that all races reported would disappear once the first races are removed. This paper presents a new two-pass on-the-fly algorithm to detect the first races in such parallel programs. The algorithm reported in this paper is an on-the-fly algorithm that detects the races that "occur first" in a particular execution of shared-memory parallel programs. The experiment has accomplished, where two certified benchmark programs which can be executed under High Performance Fortran environments to get some parameters which improve debugging performance with our algorithm. with our algorithm.

• Journal of Veterinary Clinics
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• v.36 no.1
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• pp.62-67
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• 2019

This study was performed to apply the measurement of heart rate and velocity in training horses for assessing race performance. Additionally, we aimed to identify parameters that can be used to evaluate the training level and exercise capacity. Eleven healthy 2- to 6-year-old Thoroughbreds were trained by the standard training program and heart rate and velocity were measured by using heart monitoring system and GPS. Regression analysis in heart rate and velocity data was performed to calculate velocity parameters. The mean maximal heart rate in gallop was $214{\pm}11bpm$. The mean $V_{140}$, $V_{180}$, $V_{200}$ and $VHR_{max}$ were $13.8{\pm}4.3km/h$, $37.5{\pm}3.8km/h$, $49.3{\pm}4.3km/h$ and $57.4{\pm}7.1km/h$ respectively. The mean $V_{140}$ of high performance racehorses was significantly higher than that of low performance racehorses (P < 0.05). Moreover, analyzing the correlation between velocity parameters and racing ability-related categories showed that $V_{140}$ was positively correlated with rating (P < 0.05), $V_{180}$ and $VHR_{max}$ were positively correlated with prize money per race (P < 0.05). Also, $V_{140}$ was significantly correlated with G1F (P < 0.05). The results of this study have shown that the measurement of heart rate and velocity during training could be useful methods to assess fitness for races or performance potential. Especially, $V_{140}$ is a good parameter to evaluate a performance of racehorses in Korea.

• Journal of Information Processing Systems
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• v.20 no.1
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• pp.85-92
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• 2024

In recent years, Bitcoin and Ethereum have witnessed a surge in trading activity, driven by venture capital investment and funding through initial coin offerings (ICOs) and initial exchange offerings (IEOs). This heightened interest has led to kickstarting a vibrant ecosystem for blockchain development. The total number of cryptocurrencies listed on CoinMarketCap.com has reached 2,274 highlights how dynamic and wide blockchain development landscape has grown. In blockchain development, new blockchain projects are being created by forking blockchains inspired by major cryptocurrencies such as Bitcoin and Ethereum. These projects aim to address the perceived shortcomings and improve existing technologies. Altcoins, representing these alternative cryptocurrencies, are an ongoing industry effort to improve performance and security with enhancement proposals such as Bitcoin Improvement Proposals (BIP), Ethereum Improvement Proposals (EIP), and EOSIO Enhancement Proposals (EEP). With competitive attempts to improve blockchain performance and security, an ongoing performance race between various blockchains has taken shape, each claiming its own performance advantages. In this paper, we describe the transactions contained in the blocks of each representative blockchain, and find the factors that affect the transactions per second (TPS) through transaction processing and block generation processes, and suggest their relationship with scalability.

• Journal of Animal Science and Technology
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• v.52 no.6
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• pp.459-466
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• 2010

In this study, we suggest an objective standard in selection of candidate horse mates. Korea Racing Authority provided racing records and pedigree information of 44 sires and 954 dams. The datasets were used to predict Racing Indices represented by the averages of earnings earned by offspring for each dam and sire that indicate the racing performance of its domestic progeny. Proportion of wins and second places to the number of taken races and the mean of distances for the won races of a sire were significant factors in linear model with minimum prediction errors. For dam, those factors were the average of earned money per race, number of outstanding broodmares in pedigree, and the comparable index which indicates the relative affinity with its mate. We can use the resultant model for a horse mate by choosing one of the candidates with the largest predicted value for hypothetical offspring.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.3
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• pp.301-305
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• 2008

Races must be detected for debugging OpenMP programs with directives, because they may cause unintended nondeterministic results of programs. Intel Thread Checker, an existing tool that can detects races, can not verify the existence of races and is often time-consuming and tends to require large space. To solve these problems, we developed a tool that verifies the existence of races using user requirements and analyzed model of programs. However, the tool does not have optimal performance in programs which have no synchronization for interthread coordination. This paper presents an optimal tool that applies the optimum labeling and protocol for program models without interthread coordination. For synthetic programs without interthread synchronization, the tool verifies races over 250 times faster than the previous tool on the average, even if the maximum parallelism increases in every case of which the number of total accesses are identical.